Each year, invisible to the naked eye, millions of migrating shorebirds fly from Australasia towards the tidal flats of the Yellow Sea bordering China and Korea. Each flock is made up of individuals using whatever strategies they can muster to endure the flights, weather the storms and find safe
Invisible connec tions
Why migrating shorebirds need the Yellow Sea
havens to rest and refuel on their long journeys to the breeding grounds in Siberia or Alaska. Once there, successful reproduction of as many individuals as possible is key to survival.
Shorebird migration is one of nature’s most spectacular phenomena, creating surprising and hitherto poorly understood links between countries, habitats and people. Jan van de Kam’s beautiful images, together with the compelling words of his colleagues, illustrate the magnitude of the feats performed by migrating shorebirds and the vital need for the connections that bind them to habitats to be sustained.
This book invites you to discover the risks inherent in a shorebird’s migratory lifestyle and the additional challenges created by expanding human populations. It reveals the crucial role that the shoreline of the Yellow Sea plays in shorebird migration and highlights the need for this unique and threatened habitat to be saved for future generations of birds and people.
Jan van de Kam
Invisible connec tions Phil Battley Brian McCaffery Danny Rogers Jae-Sang Hong Nial Moores Ju Yong-Ki Jan Lewis Theunis Piersma
Why migrating shorebirds need the Yellow Sea
Invisible Connections
Invisible Connections
Why migrating shorebirds need the Yellow Sea Jan van de Kam with Phil Battley, Brian McCaffery, Danny Rogers, Jae-Sang Hong, Nial Moores, Ju Yong-Ki, Jan Lewis & Theunis Piersma
INVISIBLE CONNECTIONS INVISIBLE CONNECTIONS
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4
© Text: the authors 2010; photographs: Jan van de Kam 2010 First publication: © 2008 Wetland International and Jan van de Kam
CONTENTS
© Text: the authors 2010; photographs: Jan van de Kam 2010 All rights reserved. Except under the conditions described in the Australian Copyright Act 1968 and subsequent Firstamendments, publication: © International Jan van de Kam no 2008 part ofWetland this publication may and be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, duplicating or otherwise, without the All rights reserved. Except under the owner. conditions described the Australian Copyright Act requests. 1968 and subsequent prior permission of the copyright Contact CSIRO inPUBLISHING for all permission amendments, no part of this publication may be reproduced, stored in a retrieval system or transmitted in any formNational or by any means, electronic, mechanical, photocopying, recording, duplicating or otherwise, without the Library of Australia Cataloguing-in-Publication entry prior permission of the copyright owner. Contact CSIRO PUBLISHING for all permission requests. Invisible connections : why migrating shorebirds needentry the yellow sea / National Library of Australia Cataloguing-in-Publication Danny Rogers ... [et al.] photographer, Jan van de Kam.
CONTRIBUTORS TO THIS BOOK Jan van de Kam is a Dutch wildlife photographer with a lifetime’s experience photographing, filming and writing about plants, landscapes and animals, and has an extensive list of publications to his name. In the past few years Jan has focussed primarily on shorebirds, spending considerable amounts of time photographing them at all stages of their worldwide migratory journeys.
9780643096592 (pbk.) Shore birds – Habitat – Conservation – Yellow Sea. Shore birds – Ecology – Yellow Sea. Rogers, Danny, 1966 – Kam, Jan van de. 598.330916456 Published by CSIRO PUBLISHING by (PO Box 1139) 150Published Oxford Street CSIRO PUBLISHING Collingwood VIC 3066 150 Oxford Street (PO Box 1139) Australia Collingwood 30667666 Telephone: +61 VIC 3 9662 Australia Local call: 1300 788 000 (Australia only) 3 9662 7666 Fax: Telephone: +61+61 3 9662 7555 Local call: 1300 788 000 (Australia only) Email:
[email protected] +61 3 9662 7555 WebFax: site: www.publish.csiro.au Email:
[email protected] Web site: www.publish.csiro.au Concept: Jan van de Kam and Theunis Piersma
6–7
1. Time is running out Brian McCaffery
Brian McCaffery has studied Arctic-breeding birds for three decades. He worked for the U.S. Fish and Wildlife Service as the non-game biologist at Yukon Delta National Wildlife Refuge for 20 years, focusing primarily on shorebirds. Now serving as the refuge’s education specialist, he works with Native American students exploring careers in biology and brings international researchers and artists to the refuge to promote shorebird conservation through science and art.
2. Shorebird lifestyles Phil Battley & Danny Rogers
28
3. Flyways Phil Battley
44
4. The tundra Brian McCaffery
62
5. A southern holiday? Danny Rogers
86
Jae-Sang Hong is a professor of biology and oceanography at Inha University, South Korea, with a particular interest in the ecology of benthos on tidal flats. He has worked extensively in these habitats in Europe and, especially in recent times, on the South Korean coast, focussing on the problems of how benthic animals are influenced by habitat change. Nial Moores is a co-founder and director of Birds Korea, the South Korean organisation dedicated to the conservation of birds and their habitats in Korea and the wider Yellow Sea Eco-region. Birds Korea works for the conservation of birds and their habitats through research, education and public-awareness raising activities, consultation and collaboration, and well-focussed advocacy. Nial has lived and breathed shorebird conservation in East Asia for almost 20 years – first in Japan , and since 1998 in South Korea – and has been described as one of the most experienced field birders in Eastern Asia.
CSIRO PUBLISHING publishes and distributes scientific, technical and health science books, magazines and journals from Australia to a worldwide audience and conducts these activities autonomously from the research activities of the Commonwealth Scientific and Industrial Research Organisation (CSIRO). The views expressed in this publication are those of the author(s) and do not necessarily represent those of, and should not be attributed to, the publisher or CSIRO.
Forewords
Phil Battley is a zoology lecturer in the Ecology Group at Massey University, New Zealand. His main interests are how birds manage to migrate vast distances and why individuals vary in their fuelling and migratory behaviour. Most of his work has been on knots (both Great and Red) and Bar-tailed Godwits in New Zealand and Australia, with satellite- and geolocatortracking of godwits being a recent research focus.
Danny Rogers is a shorebird biologist for the Arthur Rylah Institute (Department of Sustainability and Environment, Victoria, Australia), and chairs the scientific committee of the Australasian Wader Studies Group. His lifelong interest in shorebirds and how they choose their habitats intensified as he did a PhD on their ecology in north-western Australia, and he has since focussed on shorebird studies in coastal Victoria and South Korea, where he co-led the Saemangeum Shorebird Monitoring Program.
Photography: Jan van de Kam Concept: Jan Theunis van de Kam and Theunis Piersma Executive editor: Piersma Jan van de Kam TextPhotography: editor: Jan Lewis Executive editor: Teo Theunis Piersma – Design, The Netherlands Design and artwork: van Gerwen Text ineditor: Janxxx Lewis Printed XXX by Design and artwork: Teo van Gerwen – Design, The Netherlands Printed in China by 1010 Printing International Ltd
The first edition of this book, with text in Chinese, Korean and English, was published by Wetland International on the occasion of the 2008 Ramsar Conference in South Korea. The first edition of this book, with text in Chinese, Korean and English, was published by Wetland International In January 2008 Royal Dutch Shell and Wetlands International agreed to a strategic long-term collaborative on the occasion of the 2008 Ramsar Conference in South Korea. partnership. The five year agreement will encompass a variety of activities to enhance the conservation and In January 2008 Royal Dutch Shell and Wetlands International agreed to a strategic long-term collaborative sustainable use of wetlands by Shell and its affiliates, to raise performance standards in the energy sector and partnership. The five year agreement will encompass a variety of activities to enhance the conservation and its supply chain with respect to conservation and wise use of wetlands, and to strengthen Wetlands sustainable use of wetlands by Shell and its affiliates, to raise performance standards in the energy sector International’s capacity for engaging with business and for leadership in wetland conservation and wise use. and its supply chain with respect to conservation and wise use of wetlands, and to strengthen Wetlands One element of the partnership is to strengthen the conservation of migratory waterbirds and the wetlands they International’s capacity for engaging with business and for leadership in wetland conservation and wise use. depend on in East Asia. This book is a product to facilitate these efforts. One element of the partnership is to strengthen the conservation of migratory waterbirds and the wetlands they depend on in East Asia. This book is a product to facilitate these efforts. CSIRO PUBLISHING publishes and distributes scientific, technical and health science books, magazines and journals from Australia to a worldwide audience and conducts these activities autonomously from the research activities of the Commonwealth Scientific and Industrial Research Organisation (CSIRO). The paper this book is printed on is certified by the Forest Stewardship Council (FSC) The views expressed in this publication are those of the author(s) and do not necessarily represent those of, © 1996 FSC A.C. The FSC promotes environmentally responsible, socially beneficial and should not be attributed to, the publisher or CSIRO. and economically viable management of the world’s forests.
Flyways
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8
Ju Yong-Ki is a conservation activist, with a life-long connection with the tidal flat systems of the west coast of South Korea. His interests are broad, and encompass the significance of these tidal flats from cultural and ecological perspectives. He works closely both with scientists and with the fishing communities that make a living from the shallow seas and mudflat systems in and around Saemangeum.
6. Tidal flat specialists 106 Danny Rogers & Jae-Sang Hong
Jan Lewis lives in Broome, north-western Australia surrounded by shorebirds, and has close connections to Broome Bird Observatory and the research work undertaken in Roebuck Bay. She has travelled widely and has volunteered on a number of shorebird research projects, both on the Asian-Australasian Flyway and in West Africa. This is her first venture in text editing.
7. International partnerships Phil Battley
124
Theunis Piersma is an evolutionary biologist and leads research teams at the Royal Netherlands Institute for Sea Research (NIOZ) and the University of Groningen. His studies focus on shorebird energetics, predator-prey relationships on tidal flats and the link between resource abundance and population dynamics in habitats as far ranging as the far northern tundra and the tidal flats of South America. Theunis has strong research links with Australia and New Zealand.
8. The heart of the Flyway Nial Moores & Ju Yong-Ki
138
INVISIBLE CONNECTIONS
6
Flyways
7
Foreword by Ms Alison Russell-French
Foreword by Professor Chen Kelin
Foreword by Professor Chul-Hwan Koh
President of Birds Australia,
Professor of Northeast Institute of Geography and Agricultural
Professor of Marine Ecology, Seoul National University
and Director of Wetlands International – Oceania
Ecology (CAS), and Director of Wetlands International – China
Each year millions of waterbirds migrate in journeys of astounding distances.
Curlew, Great Knot and Curlew Sandpipers. Pressures from development
A close relationship has always existed between people and birds. The
Much has happened in the last two decades along the eastern Yellow Sea
They cross state and provincial boundaries, countries and oceans from their
and associated human disturbance in Australia and in other Flyway countries
beauty of these feathered creatures inspires us, their sheer variety and
coast. Traditionally, reclamation of tidal flats was limited to agricultural
breeding grounds in or near the Arctic Circle, moving through East and
are ever-increasing and pose escalating threats to shorebirds.
abundance dazzle us, their ability to navigate long distances across
purposes. However, in only the last two decades of the 20th century, nearly
South East–Asia, to arrive in their non-breeding grounds as far south as
This book is the result of collaboration between researchers
continents and oceans, arriving and departing in tune with the seasons,
800 km2 of coastal wetlands on the south-western coast of Korea have
Australia and New Zealand. This migration route, the East Asian – Australasian
throughout the Flyway. If shorebirds and people are to live in harmony along
sparks our imagination and enriches our appreciation of the natural world.
been lost to reclamation for industrial development. This should be
Flyway, covers 22 countries and is home to over 50 million migratory
the Flyway, we must work together to achieve outcomes that see
The migratory routes of these birds cover wetlands in many countries,
considered an ecological collapse.
waterbirds from over 250 different populations, including 28 globally
conservation and sustainable development go hand in hand. International
transcending national borders, from the Arctic to the southern hemisphere.
threatened species.
effort and collaboration to protect and conserve our Flyway shorebirds and
flats including the two estuaries of Mangyeung and Dongjin with a 33 km
their habitats is urgently needed.
Republic of Korea and the Republic of Korea, is one of the most important
long dyke, are very destructive.
Among waterbirds, it is migratory shorebirds that cover the longest
The Yellow Sea, surrounded by China, the Democratic Peoples’
Huge projects like Saemangeum, which enclosed 400 km2 of tidal
distances. Most people living in the countries along the Flyway are unaware
On behalf of Birds Australia, I commend Invisible Connections to all
coastal wetland ecosystems in the world. Its vast tidal mudflats are an essential
of their feats. Rarely will they have any idea of the immense distances that
who read it and, through it, urge greater efforts to protect and ensure a
staging site for shorebird migration between the southern and northern
have contributed to increasing public awareness about the nature and
birds travel and the dangers they face each year in responding to the call
future for one of nature’s true marvels.
Recent citizens’ movements to protect tidal wetlands from reclamation
hemispheres. During northward migration it supports more than 30% of the
beauty of these Korean tidal flats. The flats are also indispensable to local
that moves them between the northern and southern hemispheres. Through
estimated East Asian – Australasian Flyway population of 25 shorebird species
inhabitants and artisanal fisheries are common along the coast. Typically,
the wonderful images in this photographic story, Jan van de Kam gives a
and carries almost the entire flyway population for 15 species.
Manila clam, surf clam and razor clam are harvested by local residents
unique glimpse into the annual cycle of migration that millions of shorebirds
To assess shorebird numbers, and to accurately understand the
simply going onto the tidal flats and digging them up with hooks. Even
make and the challenges they face on their dramatic journeys.
utilisation of the Yellow Sea during migration, Wetlands International in
lugworms are collected by the bare-hand method for export to Japan as
Among many other insights the book reveals, Invisible Connections
Australia and China, together with local Chinese government agencies and
angling bait.
shows us shorebirds busily feeding on the rich tidal flats of the Yellow Sea,
nature reserves around the Yellow Sea coastline, have worked collaboratively
often side by side with people. This book focuses on the Yellow Sea because
for the past 12 years. Workshops, training courses, field surveys and
coastal wetlands. A survey we conducted in the Hwaseong tidal flat near
of its critical role as the premier staging site for shorebirds in the Flyway.
banding of shorebirds have been organised and information for the public
Seoul showed that annual production yielded about 150 razor clams, or
Without access to these tidal flats and the wealth of invertebrate life they
on waterbirds and wetlands has been disseminated.
over 3 kg in wet weight, per square metre. This kind of productivity not only
contain, the very nature of shorebird migration is threatened. We now know,
supports humans, but also migrating shorebirds in the East Asian –
through satellite tracking, that Bar-tailed Godwits fly immense distances,
North Korea live on the shores of the Yellow Sea and the tidal flats are of
Australasian Flyway.
sometimes exceeding 10 000 km, non-stop from New Zealand and Australia
major importance for shellfish harvesting. Often people and shorebirds can
to the Yellow Sea. Upon landing, they are in desperate need of food to fuel
be seen working side by side. However, rapid population and economic
reclamation projects, even everyday people in the eastern Yellow Sea
up for their next flights to the breeding grounds in Alaska or Siberia. Without
growth have led to serious degradation and loss of wetland areas and
region want to protect the tidal flats from further deterioration and
these tidal flats, their very survival is at great risk.
impacted on the regional environment in ways which may jeopardise its
destruction. National policy in South Korea is also turning from reclamation
Wetland habitats worldwide are under great threat. The Ramsar
continued use by shorebirds. Adoption of wise-use principles for the tidal
to conservation and wise use. However, we think the turning process
Convention on Wetlands of National Significance to which Australia is a
flats of the Yellow Sea is vital to ensure that this wonderful region continues
towards conservation has been slow and late, and we have already paid
signatory makes clear the international responsibility all governments have
to be sustainable for both shorebirds and people. I hope this publication,
too great a price for it. There still remains much to do towards securing
to protect important wetland habitats. Long-term research in Australia by
with its fantastic photos of shorebirds, will encourage readers to give
conservation of the Yellow Sea tidal flats. In this respect, this book will
Birds Australia’s Australasian Wader Study Group is already revealing
attention to the importance of ecologically sustainable development of this
surely be a great contribution to enhancing public awareness about the
declining numbers of some species of shorebirds, particularly Eastern
highly significant region.
unique and precious nature of the tidal flats.
Approximately 600 million people from China, South Korea and
High productivity is an important characteristic of the Yellow Sea
Now, through public debate in the media about the pros and cons of
8
Invisible connec tions
TIME IS RUNNING OUT 9
1
Curlew Sandpipers feeding on the shores of the Yellow Sea.
Time is running out Brian McCaffery High above the Pacific Ocean, each year in April
This network of connections is as colourful and
and night, hundreds or thousands of metres
a combination of rigorous field work and novel
and the countries stretching along the Pacific
ambassadors fly readily from country to country,
and May, great flocks of shorebirds stream north
textured as the multi-layered plumage that
above vast tracts of the empty Pacific, they
laboratory experimentation, we are just starting
Rim are already connected in important ways –
with dependence on all but allegiance to none.
towards the Yellow Sea. From the continental
adorns the wing of a turnstone, yet, for much of
escape our detection. We simply cannot observe
to comprehend the details of how shorebirds
by
and
A feather grown to grace the breast of a
shores and archipelagos of Australasia, godwits,
the year and for most people, goes unnoticed. In
their daunting achievements – flights lasting
prepare for and then complete their long
agreements. Less frequently, however, do we
godwit in New Zealand may someday be used to
knots, stints and plovers race through the skies.
this book, through the beautiful images of Jan
hours or days, without stopping to rest, feed or
migrations. We are at the threshold of the mystery,
consider the ecological connections between
line the nest of a tundra-dwelling songbird near
Bound for the tundra of Siberia and Alaska, they
van de Kam and the compelling words of his
sleep. Not only are these shorebirds usually
and as we increase our understanding of the
these nations, spun by the dramatic journeys of
the Bering Sea. Tiny grains of stony detritus
first pause to rest and refuel along the shorelines
colleagues, we hope to make these connections
beyond our sight, but they are also beyond our
world from a bird’s perspective, it is clear there
migratory birds. Their globe-spanning flights link
washed down from the highlands of central
of East Asia. As they fly and land, and then lift
more obvious.
imaginations. However, with the help of recent
are untold wonders to discover, important
countries separated by thousands of kilometres,
China may frame the burrow of a mud-dwelling
history
and
commerce,
alliances
into the clouds again, the flocks weave unseen
During much of their lives, and particularly
advances in technology, scientists have finally
connections to be made and urgent threats that
as well as those separated by ideology, language
worm in the Yellow Sea, a worm that helps fuel
threads that bind them to the world and its myriad
while undertaking their epic migrations, migratory
begun to understand how impressive the
demand our response.
and culture. In a world where diplomacy can
the flight of a Great Knot when it stops en route
inhabitants in diverse and unexpected ways.
shorebirds are literally invisible to us. Flying day
migratory flights of shorebirds truly are. Through
seem
from the tropical coast of Australia to the wind-
From a human perspective, Australasia
a
daunting
challenge,
these
avian
10
Invisible connec tions
TIME IS RUNNING OUT 11
blown summits of the Chukotka Peninsula. Near
images make clear that there are times and
Perhaps it is not surprising that those
drain steadily through the hourglass of potential
Through this book, we invite you to
the shores of the Sea of Ohkotsk, a young
places when these itinerant visitors gather in
people most intimately familiar with migrant
and possibility. Consider the tiny Red-necked
reconsider the muddy flats of the Yellow Sea.
Nordmann’s Greenshank may leap from its nest
huge numbers. At certain special places where
shorebirds are also those most likely to dwell on
Stint. Each year, flocks of these diminutive
Under a golden sun, the dull, weary surface of
in a tree to gorge among the wetlands of Sakhalin,
land and sea meet, immense flocks congregate
the margins, not only of the land and sea, but of
sandpipers pass through the Yellow Sea. Petite
the mudflats can be transformed into a sparkling
only to fall prey months later to a hungry raptor
to prepare themselves for the next stages of their
society as well. Around the Yellow Sea, shorebirds
bundles of avian energy, they feed eagerly on the
plain of diamonds. Such glimpses remind us
along the shores of the South China Sea. A
journey. The Yellow Sea is such a place. Smoky
often share the mudflats with Chinese and
flats, dashing from spot to spot in a whirlwind of
unequivocally that the Yellow Sea is an ecological
singing male Spoon-billed Sandpiper may perch
curtains of birds rise and fall above a shimmering
Korean villagers who depend on those same
activity. But they can do nothing to ensure that
treasure. It may have lost some of its original
atop the weathered rib of an Arctic whale at the
horizon as they move to and from feeding sites
mudflats for succour and sustenance. Far to the
their muddy oasis survives to support their
lustre, but its value remains inestimable. Through
summer solstice, then leave dainty tracks across
or dodge the attacks of marauding falcons. For a
north, tens of thousands of godwits congregate
descendants. Such power lies beyond the reach
the lives of our world’s long-distance travellers,
the vast grey tidal flats of the Bay of Bengal
few days or weeks of the year, these massed
along the shores of Alaska’s Bering Sea, where
of their feathered wings. Instead, that power
we invite you to discover the importance of the
before the autumnal equinox. Undaunted by the
flocks of shorebirds are stunningly visible and
Yup’ik Eskimo hunters still maintain their
resides in us and, as habitats degrade and
priceless ecological jewel that is the Yellow Sea,
borders drawn on our two-dimensional maps,
conspicuous, creating some of the greatest
subsistence traditions and harvest godwits to
disappear, little time remains to use that power
and to play your part in ensuring it is saved for
these feathered travellers remind us that we are
wildlife spectacles on the planet. Yet they usually
feed their communities. A few weeks later,
wisely. If we wish to protect the Yellow Sea, if the
future generations of birds and people.
connected
and
pass beyond our observation, remaining invisible
godwits arrive in the distant south, where they
Yellow Sea is to remain a place where both food
substantive than those set forth in the carefully
because they inhabit a world that, for most of us,
may remind Maori families of the role godwits
and wonder can be harvested, we need to act. If
crafted phrases of treaty and trade.
lies beyond the scope of our daily lives and at the
played in their ancestors’ discovery of New
margins of our consciousness – the world of
Zealand.
in
ways
more
profound
Although these birds remain far from us during most of their lives, Jan van de Kam’s
intertidal mud.
Shorebirds and a fisherman search for shellfish on the mudflats of Saemangeum.
Although these connections between rural
the Yellow Sea is to nourish our bodies and our spirits while it continues nourishing birds along an entire flyway, then we need to act now.
people and migrant shorebirds may be quite
The world of empty flats and muddy tides
tangible, there are other connections between
For the racing skeins and swirling clouds
humans and wildlife that often escape detection;
of migrant birds, the Yellow Sea is the nexus of
appreciation; the casual observer may be left
invisible connections that have the power to
their
shorelines
stranded far from the passion that leads many to
either sustain or destroy the critical nodes that
throughout East Asia are vitally important to
rally to the defence of other habitats around the
support shorebird migrations. Far from the slick
migrant birds, and many of these areas are at
world. Towering mountains, verdant rainforests
grey ooze and salty tang of the mudflats,
great risk. Among them, however, the tidal flats
and raging rivers readily inspire global citizens to
decisions made in corporate boardrooms, the
of the Yellow Sea are paramount. Birds from
preserve and protect those special places. But
halls of government and the marketplace will
across a broad swathe of the equatorial and
the realm of mud elicits fewer advocates. There
impact on the flocks of birds that surge up and
southern latitudes converge there every Arctic
are perhaps few among us whose spirits are
down the flyways each year. Those decisions
spring, and then fan out to occupy tundra-
lifted and whose will is inspired by a vista of mud
may benefit wildlife and natural habitats, but, in
covered mountains and plains from central
stretching to the horizon. This book aims to
the modern world of growth and development,
Siberia in the west to Alaska in the east. A similar
change that. By tracing the connections that link
are more likely to be to their detriment.
convergence occurs during southward migration.
the birds of the Yellow Sea to the dozens of
For these birds the Yellow Sea is much like the
countries and millions of people in eastern Asia,
narrow neck of an hourglass.
Australasia and Alaska, we hope to encourage
A challenging combination: many places important for shorebirds are also industrial sites.
migration.
Wetlands
and
may
at
first
glance
resist
intimacy
and
Just as the shorebird flocks twist and swirl
our readers to make these vital connections,
as they pass through the ecological bottleneck
connections between the decisions we make
of the Yellow Sea, so too do the sands of time
and the fate of far-ranging birds.
Chinese students discover the amazing variety of shorebird shapes and plumage. As the decision makers of the future, it is imperative that they become aware of the ecological wealth and importance of their Yellow Sea home.
12
Invisible connec tions
TIME IS RUNNING OUT 13 Twice a day dramatic changes occur at the margins of the sea. At high tide, water covers all; as the water recedes, vast mudflats are exposed. First impressions suggest hardly any life in this mud, but, in reality, it is teeming with small organisms such as crabs, shellfish and worms that can survive in the ever-changing environment. This rich food source is exploited by other specialists, the many species of shorebirds which are completely dependent on these mudflats. They include Bar-tailed Godwits (right), Red Knots and Curlew Sandpipers (below).
14
Invisible connec tions
TIME IS RUNNING OUT 15
Photo copyright Robert E. Gill, Jr., Alaska
Shorebird migration creates fascinating global connections. In March (left), as shorebirds gather on the white shell ridges of the Miranda Nature Reserve in New Zealand to prepare for their northward migration, birdwatchers wait to bid them farewell. In May in Alaska (right), the arrival of the same birds on mudflats surrounded by snow-covered mountains and volcanic peaks is welcomed with shorebird festivals.
16
Invisible connec tions
TIME IS RUNNING OUT 17
Shorebirds are not only able to travel immense distances and find their way around the globe, they are also capable of adapting to extreme weather situations. These Bar-tailed Godwits and Red Knots (left) look very comfortable in the sun-baked sand dunes of New Zealand. Two months later, after a journey of 17 000 kilometres in two non-stop flights, the godwits still have the energy to perform acrobatic display flights above their snowy breeding grounds on the tundra of Alaska.
18
Invisible connec tions
The rich mudflats of the Yellow Sea are an essential stopover site for migrating shorebirds. Here they build up fat reserves by eating as much as they can to fuel the next stage of their journey. The world’s population of Great Knots (above) refuels there each year during their flights between Australia and Siberia. The Yellow Sea mudflats are also indispensable for the critically endangered Spoon-billed Sandpiper (right), a species which has an estimated global population of possibly fewer than 100 breeding pairs.
TIME IS RUNNING OUT 19
20
Invisible connec tions
TIME IS RUNNING OUT 21
At some places in the Yellow Sea, migratory shorebird habitat is protected. At Yalu Jiang National Nature Reserve in northern China, observation hides and artificial roosting sites have been built in the fishponds behind the sea wall (left), giving people the opportunity to see and admire these international travellers. However, most Yellow Sea residents, such as these visitors to the Song Do mudflats in Incheon City, South Korea, are primarily interested in tidal areas for the shellfish they hope to harvest there.
22
Invisible connec tions
TIME IS RUNNING OUT 23 The shoreline of the Yellow Sea supports millions of people, and the tidal flats are used for a broad range of human activities including shipping, industry and the harvesting of marine food. With good planning, both the interests of people and birds can be met, but once a tidal flat is reclaimed (right) neither shorebirds nor people can harvest food there any more.
24
Invisible connec tions
TIME IS RUNNING OUT 25
To ensure that management plans meet the needs of shorebirds, we must learn more about how they use their habitats throughout the year. Global scientific partnerships are being formed to undertake more detailed studies of the worldwide migration of shorebirds. Tracking the movements and monitoring the survival of known individuals are particularly important components of shorebird conservation biology. To do this, individual birds are marked with numbered metal bands and unique combinations of coloured leg-bands or engraved plastic leg-flags. The bands and flags of the Bar-tailed Godwit above show it to be a bird that was banded in north-west Australia.
26
Invisible connec tions
From small shorebirds such as Sanderlings (this page) to larger birds such as Bar-tailed Godwits (right), the amazing ability of these beautiful birds to navigate long distances across continents and oceans, arriving and departing in tune with the seasons, sparks our imagination and enriches our appreciation of the natural world. We must ensure their survival – it is up to us!
TIME IS RUNNING OUT 27
28
Invisible connec tions
Shorebird lifest yles 29
2
Shorebird lifestyles Phil Battley & Danny Rogers As the tide rises on a tidal flat, a mass of birds of
residents, but others will have flown thousands
habitat either. Herons and egrets are often found
and appearance, differences that correlate with
see. Between these extremes lies a range of
with large eyes and a ‘wait and see’ foraging
varied sizes is forced together by the incoming
of kilometres to be here. This scene will be
wading along shorelines, yet are not members of
their different ecologies. In most places the
subtle adaptations. Godwits use the flexible tip
mode. They rely on invertebrates betraying their
water. From a distance, it may seem impossible
repeated throughout the flyway from Alaska and
the
be
commonest species are the sandpipers, which
of their long bill to grasp buried polychaete
presence by moving on the mud surface, at
to tell them apart. However, closer examination
Russia in the north to New Zealand in the south.
shorebirds. And some bird species universally
range in size from the sparrow-sized Red-necked
worms; swimming phalaropes use the surface
which point they run quickly and attempt to grasp
through binoculars or a telescope will often reveal
What exactly are these birds that we call
considered to be shorebirds can go through a
Stint to the much larger Eastern Curlew, whose
tension of water to draw up microscopic
the oblivious crab, shrimp, worm or insect.
a surprisingly diverse suite of species. Long-
shorebirds? It is a surprisingly difficult question
lifetime
shoreline!
bill alone is longer than an entire stint. The curved
crustaceans; Red Knots use special remote-
Oystercatchers take the concept of an insensitive
legged herons, egrets and spoonbills wade in the
to answer. Taxonomically, shorebirds belong to
Nevertheless, bird watchers seem to understand
bill of a curlew, or the similarly shaped one of a
sensing receptors in the bill-tip to detect buried
bill one step further. Their long orange dagger is
water, gulls gather in noisy flocks, and ducks and
one of 13 families in the order Charadriiformes.
what shorebirds include – the plovers, sandpipers
Whimbrel, allows it to make complex twisting
shellfish, which are hauled from the mud and
used as a mechanical tool to open large shellfish.
geese feed in muddy puddles. Meanwhile, milling
Confusingly, this order also includes some
and their relatives that generally live on the
probes as it pursues crabs and shrimps down
swallowed whole.
They wedge the tip between the two sides of a
shorebirds
sort
closely related bird families – the skuas, gulls,
coastal fringe between land and sea.
muddy burrows. Short-billed stints feed with a
The other major group of shorebirds, the
bivalve and push in to sever the muscle holding
themselves into a size hierarchy at the water’s
terns and auks – that are not regarded as
Although fairly similar at first glance, these
frenetic sewing-machine action, trapping minute
plovers and their relatives, do not have such
the valves closed, or prise limpets off rocky
edge. Some of these birds may be local-breeding
shorebirds. There is no clear-cut definition by
shorebirds are actually quite different in structure
organisms almost too small for the human eye to
sensitive bills. Their short, hard bill is teamed
shores. Their bills grow continuously and would
(also
known
as
waders)
Charadriiformes
without
ever
or
considered
visiting
a
to
Eastern Curlew and Curlew Sandpipers feeding at the tide edge.
30
Invisible connec tions
Shorebird lifest yles 31
become excessively long if the tips were not
southward migration. That site is currently in the
continuously worn down when feeding or
process of being destroyed and converted into
chiselling at hard prey.
industrial and agricultural land. The loss of such
Migratory shorebirds are typically the most
wetlands may lead to the loss of entire species
abundant birds found on tidal flats, where the
like the Spoon-billed Sandpiper.
daily ebb of the surrounding sea, normally twice
Spoon-billed Sandpipers may be especially
a day, uncovers a rich larder of food, covering it
vulnerable to changes because they are highly
up again as the tide comes in. These tides are
specialised. The precise role of the distinctive
the drivers of the daily routines of coastal
spatulate bill when foraging is not yet clear, but it
shorebirds. Rather than being governed by
may only be effective in quite limited sediment
daylight and sleeping during the night, their sharp
types. Throughout their range they are found in
eyesight and sensitive bill tips enable them to
very few locations, reinforcing the idea that the
feed in darkness. Consequently, shorebirds’
species has limited options for where to live. In
activity cycles do not match those of humans –
this case, the presence of a tidal flat is not enough
Feeding shorebirds can be surprisingly tolerant of bird-watchers.
birds often roost in the daytime, when disturbance
– it must be the right kind of tidal flat. Other
from humans is most likely.
species are more flexible in their requirements.
During the day shorebirds will be in danger
why birds flock together. Being in a large group
of predation from raptors; in some places they
means that there are more eyes keeping watch;
common.
have to fear owls at night. This is why even
it also means that if an attack does happen, there
Greenshank were recently found on a non-
sleeping shorebirds maintain a wary alertness. If
is less chance that any individual bird will be
breeding ground in Malaysia, and on a staging
you take a close look at such ‘sleeping’
killed. Its chance of being caught is ‘diluted’ by
site in the Geum Estuary, South Korea. Each
individuals, you will notice the quick opening and
Roosting flock of shorebirds.
sheer weight of numbers.
Unfortunately, not all species are that Record
groups
of
Nordmann’s
numbered a mere 70 birds, but represented
closing of birds’ eyes as they check for potential
These numbers can be staggering. Fifty
danger. The need to roost securely is one reason
freezing.
tide beach-wrack on sandy shores, sucking
Tidal flats are an essential part of shorebird
polychaete worms out of their tubes, or even
life. They provide a range of services to such
breaking into eggs in tern colonies.
birds – food for some, roosting space for others
population of 500–1000 individuals. Nordmann’s
specialised to use tidal habitats, some species
rich diversity found along the coastal zone. Here
in single flocks on migration through the Yellow
Greenshank is an Asian specialty, breeding on
habitually use non-tidal areas. Some of the head-
you can find birds that fly over 10 000 kilometres
Sea, their seemingly synchronised, twisting flight
Sakhalin Island and wintering in South-East Asia.
bobbing ‘shanks’ are more often found on
without stopping standing alongside birds that
manoeuvres providing an incredible visual
Another Asian endemic is even rarer: the Spoon-
freshwater ponds than on tidal flats, and the
may not leave their local stretch of beach in an
spectacle. Dunlin crowd the mudflat edges as
billed Sandpiper.
cryptic, long-billed snipes are birds of swamps
entire year. A New Zealand Dotterel may defend
visiting
and wet paddocks. A few species, such as the
its nest from the milling feet of roosting Bar-tailed
In north-west Australia in 2004, almost 2.9 million
birdwatchers, Spoon-billed Sandpiper numbers
Long-billed Plover in Asia, use rocky riverbeds
Godwits, which a few months later may stand
Oriental
a
have plummeted over the past two decades. It is
throughout the year.
alongside breeding Kentish Plovers in the Yellow
235-kilometre stretch of Eighty Mile Beach. This
thought that fewer than 100 breeding pairs
For most migratory shorebird species,
Sea, and later breed in sight of nesting Grey
must rate as one of the largest congregations of
remain, nesting only on the coastal plains of the
travelling to the breeding grounds brings a
Plovers in the Alaskan mountains. Birds like
any species of bird in the world.
Chukotka Peninsula in eastern Russia. The
dramatic change in habitat. Gone are the coastal
these need a chain of wetlands around the globe
largest numbers of Spoon-billed Sandpipers
beaches and tidal flats, the immobile bivalves,
to ensure both their survival and the persistence
known anywhere in the world used to occur at
the crabs and polychaetes; instead they find
of one of nature’s most wondrous phenomena,
Saemangeum in South Korea, particularly on
themselves inland in habitats varying from
migration.
descended
along
Oriental Pratincoles bathing in north-west Australia.
priority
estimated
over with their bills, rummaging through high-
thousand Great Knots can congregate together
high
species’
where the temperature may hover just above
– and the presence of these birds adds to the
Pratincoles
the
can be found on rocky shores flicking stones
Although many shorebird species are
A
of
Photo copyright Shim Kyu-Sik, South Korea
scorching high-altitude deserts to Arctic tundras
global
the tide comes in, chattering noisily and excitedly.
5–10%
Nordmann’s Greenshanks (right) with Terek Sandpipers and a Dunlin.
Ruddy Turnstones may be the extreme – they
species
for
32
Invisible connec tions
Shorebird lifest yles 33
Roebuck Bay, north-west Australia, is internationally renowned for its shorebirds. At high tide birdwatchers can enjoy the spectacle of thousands of birds packed into roosts on sandy beaches. The birds follow the tideline closely as the tide begins to ebb, ensuring that they do not miss any foraging opportunities during the precious hours when the tidal flats are exposed.
34
Invisible connec tions
Shorebird lifest yles 35
The long bill of a Bar-tailed Godwit can locate and catch prey buried deep in the mud. Godwits forage so efficiently that they can increase their mass by nearly 50% in the month preceding departure from Australia or New Zealand. This extra weight, in the form of fat and muscle, fuels the first leg of their northward migration, which brings over 50 000 godwits together in Yalu Jiang National Nature Reserve in China (right). Here, feeding on the rich mudflats of the Yellow Sea, birds can regain sufficient weight to fuel the last leg of their flight to the breeding grounds.
36
Invisible connec tions
Shorebird lifest yles 37 Male Eastern Curlews have shorter bills than females, but both use their elongated bills to extract large crabs from deep burrows (right). The up-curved bill of Terek Sandpipers (upper left) is another kind of crabcatching tool. The short bill of Greater Sand Plovers (centre left) is used to seize small animals from the surface; the straight bill of the Common Greenshank (lower left) is often used to lunge for fish; however, the precise function of the remarkable bill of the Spoon-billed Sandpiper (far left) is still a mystery.
Shorebird lifest yles 39 Small sandpipers, like this Dunlin (right), search mudflats with rapid pecks at the surface, leaving a distinctive foraging trail. They only probe deeply when potential prey items are located. The bills of shorebirds are surprisingly flexible. Muscles in the back of the head can move the tips of the mandibles, enabling species like Bar-tailed Godwits (left) to probe to full bill-depth and still use the bill-tip as a pair of tweezers to pick up delicate prey items.
40
Invisible connec tions
Shorebird lifest yles 41
When high tide covers the feeding grounds shorebirds congregate at roosts to rest. Sometimes they gather on rocky shores or in quiet clearings within mangrove forests. Birds of prey are their main threat. While there is safety in numbers, sleeping birds often open an eye to look around; others regularly scan the sky for predators.
42
Invisible connec tions
Shorebirds change their appearance during the year. In Australia, Curlew Sandpipers are grey and white. They become more brightly coloured as they migrate through the Yellow Sea on their way to the breeding grounds in Siberia. Before departure, Red Knots in New Zealand (far right) also moult into a reddish breeding plumage.
Shorebird lifest yles 43
44
Invisible connec tions
Fly ways 45
3 Bar-tailed Godwits in flight.
Flyways Phil Battley Invisible to the naked human eye, above the land
Flyways are a human construct, a way of
just shorebirds that use such flyways, however;
up and store energy for flight, and build up their
of some 6000–8000 kilometres, which until
11 500-kilometre flight, which takes more than
and oceans of the world, lie some of the planet’s
viewing the world in simple terms. They describe
waterfowl such as ducks, geese and swans
muscles to carry this extra weight, often leaving
recently would have been considered one of the
a week.
busiest highways. Twice a year, these connecting
the movements of birds through countries,
migrate in their millions along similar pathways
the breeding area for nearby tidal flats where rich
longest flights known in the bird world.
corridors of activity hum to the endless beats of
across continents and even across oceans. The
around the world.
feeding awaits.
millions of wings as birds commute between their
East Asian – Australasian Flyway stretches from
The
seasonal homes. On their way north, adults in
tailed Godwits that breed in Alaska. After
Sandpipers make a curious dogleg migration.
the middle of Siberia in the west across to Alaska
hemisphere for most of the birds in the East
birds may be the Sea of Okhotsk in eastern Russia
breeding on the coastal and mountain tundra,
After hatching in Siberia, thousands of young birds
rich breeding plumage head for distant breeding
in the east, compressing through eastern Asia
Asian – Australasian Flyway is Russia, where the
or the Yellow Sea. While little is known in detail
godwits congregate on the rich tidal flats
cross the Bering Sea to Alaska where they fatten
grounds. A few months later they return south
and spreading out across South-East Asia, to
vast expanses of Arctic and sub-Arctic tundra
about these southward refuelling stops, it seems
adjoining the Yukon-Kuskokwim Delta to fuel up
up on seeds and invertebrates in the shallow pools
again, accompanied or followed by the season’s
Australia and New Zealand. More than 50
and
productive
likely that species such as Great Knots and Red
for a truly epic flight – a non-stop trans-Pacific
around the edge of the tundra. Without any adults
young making their first forays into a world of
shorebird species migrate up and down this
environments for birds to quickly breed and raise
Knots may launch off from these sites and overfly
crossing. Researchers from the USA and New
to join up with, they set out on journeys over
unknown possibilities. The pathways these birds
Flyway, and in doing so they connect virtually
a family. After breeding, these birds fuel up before
eastern Asia on their way south, travelling without
Zealand have recently discovered that godwits
uncharted waters that will lead them southwards,
funnel through are known as flyways.
every country in the Asia-Pacific region. It is not
making long southward flights. They will fatten
stopping directly to Australia. This entails a flight
heading to New Zealand make a massive
possibly all the way to Melanesia or Australia.
rich
in
the
launch off from Alaska. Juvenile Sharp-tailed
The first major refuelling stop for many
provide
point
That honour now clearly goes to the Bar-
northern
taiga
starting
Godwits are not the only East Asian bird to
and
46
Invisible connec tions
Fly ways 47
But most birds do not make these very
the southernmost extremity of the Flyway, just
cells. They may have shrunken their digestive
aiming for the northern or eastern Yellow Sea,
long flights. Instead, they depend on a network
before northward take-off, Bar-tailed Godwits in
organs before taking off to lighten their load.
600–1000 kilometres further on, but will make a
of habitats along the Flyway, safe and undisturbed
New Zealand can already be heard making the
When flying, their large fat deposits will be burnt
short stopover until the weather improves.
sites where they can replenish themselves after
call used in aerial displays over their tundra
as fuel. But that is not all – their muscles and
Humans often have an image of migratory
flights and get ready for the next one. This is
breeding grounds!
other organs will also get smaller. The protein that
birds as frail, slight creatures battling their way
especially true for young birds, which flock to
The Yellow Sea is pivotal to the lives of the
is broken down from these tissues will be reused
across the globe, no doubt inspired by how tiny
the shores of the Yellow Sea in August and
Flyway migrants during their northward migration.
in chemical reactions that allow the rapid energy
some species are. But many migrating shorebirds
September before moving on to their eventual
This is their final opportunity to prepare for
delivery to continue for the length of the journey.
do not fit that picture at all. They are beefy,
wintering sites further south. Juveniles have no
breeding, to ensure they arrive with enough
When the birds arrive after migration they
humpbacked bundles of muscle and fat; finely
experience of migration. They rely on inherited
energy to display and court mates, defend
will be a shadow of what they were a few days
honed creatures that cut through the sky at
genetic programs that can give only a general
territories, make eggs and cope with any freezing
earlier. They will be skinny, tired and thirsty. Not all
speeds that may average 60 kilometres/hour.
plan of where to migrate. Consequently, they are
periods that may occur. In late April and May, the
birds will have survived the flight; some may have
They have been migrating for millennia and treat
often found in groups in unexpected places,
Yellow Sea provides one of the greatest
hit headwinds and not been able to reach their
the planet’s vast distances as an opportunity
such as surf beaches where most shorebirds
spectacles of the shorebird world. At Yalu Jiang
destination. Others may have stopped short of
rather than a limitation. They deserve our utmost
usually do not live, and they may use places that
National Nature Reserve in China, half the Bar-
their eventual goal. Poor weather often forces
admiration.
tailed Godwits from the Flyway gather in vast
birds down at Chongming Dongtan Nature
flocks, paying no heed to human borders as they
Reserve, at the mouth of the Yangtze River on the
flit across the Yalu River to Korean tidal flats to
coast of China. Many of these birds will have been
adults pass by. Juvenile Sharp-tailed Sandpipers in Alaska: hatched in Siberia, and en route to Australian non-breeding grounds.
50
10000 km
00
km
roost or feed. Massed flights of tens of thousands Adults move more directly to their non-
The northward migration is quite a different
of Great Knots twist and turn over mudflats
breeding destinations, using fewer sites en route
affair from the southward one. Most obviously,
teeming with the small shellfish on which they
than juveniles. This migration covers quite a wide
birds are resplendent in their breeding dress,
depend. Some of these key sites hold over
time span, as birds from various tundra regions
spruced up and ready to attract a mate on the
100 000 birds, and collectively the Yellow Sea
pass through at different times, and males
breeding grounds. There is also a strict time
holds probably two million birds through the
and females leave the breeding grounds at
constraint on the birds’ movements. They cannot
migration season.
different times depending on whether or
just fly north at any time – they are heading
How do shorebirds make these incredible
not they tend chicks. Because birds may
towards areas that are only just emerging from
journeys? The trick is to combine obesity and
pass through an area quite quickly on
the grip of a bitter and inhospitable winter. The
athleticism. Their performance is a paradox in
southward migration, they do not usually
tundra will still be frozen in April, in some places
human terms – birds may be 30, 40 or even 50%
form the vast flocks that are sighted
until early June, so the migration is timed to allow
fat when they leave for a migratory journey.
during northward migration.
birds to reach the breeding grounds just when
Humans would be classified as clinically obese at
the snow starts to melt. During April and May in
such levels. Yet, once in the air, these birds can
the final stopover sites on migration, the mudflats
work as hard as the fittest human athlete, and
are
shorebirds.
keep it up for many days on end. They will have
Hormones surging, the breeding season is just
built up the size of their muscles, heart and lungs
around the corner. Calls usually reserved for the
while fattening, and increased the activity of the
breeding grounds cascade from flying birds. At
enzymes responsible for delivering energy to
The East Asian – Australasian Flyway links Siberia, Alaska and Central Asia with Australasia. The map highlights how migration routes converge on the Yellow Sea, and the long distances covered.
teeming
with
fat,
excited
Bar-tailed Godwits in Alaska, ‘fuelled up’ for the long flight to New Zealand.
48
Invisible connec tions
Flying birds, like this flock of Terek Sandpipers, are obvious in tidal areas. But it is not so easy to observe migrating shorebirds, because they usually fly at high altitudes. If lucky, you can see their departure. Groups of birds gather on a mudflat calling persistently. Some fly up and return again, drawing more birds into the group as the calling becomes more agitated. Suddenly the whole group takes off, climbing higher and higher, sometimes circling to allow stragglers to catch up. The ragged flock becomes structured, forms straight lines and then an aerodynamic V-formation, and is quickly lost from human sight.
Fly ways 49
50
Invisible connec tions
Fly ways 51 In the non-breeding season in Australia, Great Knots occur in dense flocks. Here at Eighty Mile Beach they feed on small shellfish. By contrast, they are solitary when breeding in the rocky mountains of Siberia, camouflaged in chestnut and black breeding plumage which they started to moult into before they left the non-breeding grounds and completed during their migratory stopover in the Yellow Sea.
52
Invisible connec tions
Fly ways 53 In an amazing performance, small shorebirds like the 25- to 30-gram Red-necked Stint migrate more than 10 000 kilometres from Australian non-breeding grounds (far left) to foothill tundras in Siberia, arriving as the snow starts to melt. The female produces four eggs that together weigh as much as she does. Juvenile birds (below) are identifiable by the pale fringing on their wing coverts. Four weeks after hatching, these birds are able to fly to Australia.
54
Invisible connec tions
In north-west Australia many shorebirds roost on the rocky shore at high tide. Several species are packed tightly together in this picture (right): Great Knot, Red Knot, Curlew Sandpiper, Broad-billed Sandpiper, Ruddy Turnstone, Greater Sand Plover, Red-necked Stint, Terek Sandpiper and Grey-tailed Tattler. The Bar-tailed Godwits (above) are on their way! They have just taken off from Roebuck Bay in north-west Australia and are settling into a V-formation which will increase the aerodynamic efficiency of their flight. It is a helpful energy saving, given that these birds will next touch land on the shores of the Yellow Sea after a non-stop flight of 6400 kilometres lasting 4.5 to 5 days. Bar-tailed Godwits are among the most sexually dimorphic of shorebirds, and the differences between females and the smaller, redder males are readily visible here.
Fly ways 55
56
Invisible connec tions
Fly ways 57
The Yellow Sea is the main staging area for shorebirds migrating from Australasia to the breeding grounds in Siberia and Alaska. A key place is Yalu Jiang National Nature Reserve in northern China. At high tide huge flocks, mostly of Bar-tailed Godwits and Great Knots, roost in the fishponds along the coast. At low tide they swirl over the vast mudflats where shorebirds and local fishermen search for shellfish.
58
Invisible connec tions
Before their northward migration, Ruddy Turnstones (top) and Red Knots in New Zealand not only change their plumage, but also their shape. A thick layer of fat is deposited under the skin, and they become pot-bellied and heavy-breasted. This is obvious in the colourful Red Knots (above right) about to migrate in March, and contrasts markedly with the leaner newly arrived juvenile (above left, photographed in September). The bulky Bar-tailed Godwits shown on the far right are about to embark on the longest non-stop migratory flight in the bird world, from Alaska to New Zealand.
Fly ways 59
60
Invisible connec tions
Fly ways 61
After breeding, huge flocks of shorebirds feed on the rich tidal flats of Alaska and Siberia, building up enough fat for their long flights south. But not all birds make it. A skull and a few feathers are all that remains of this young Bar-tailed Godwit, surrounded by a Peregrine Falcon’s talon marks in the sand. When shorebirds are heavy with fuel for migration they become less agile, and therefore easier prey for predators. Migrating birds have to cope with many such natural dangers and always seem to live on the edge of survival. They are therefore particularly vulnerable to man-made changes in their environment.
62
The tundra 63
Invisible connec tions
4
The tundra Brian McCaffery Far to the north of the Yellow Sea, a frozen
of brown vegetation, patches that grow and
reach a few centimetres into the frigid air. At
of permafrost – permanently frozen, icy soil that
With nowhere else to go, the melt-water forms
conditions? The secret lies in the rich mudflats
expanse awaits the advent of spring. The broad
multiply. Bit by soggy bit, the tundra is exposed.
higher latitudes and elevations, the vegetation
chills the ground above it and resists penetration
complex networks of shallow marshes, lakes
of the Yellow Sea. Along the shorelines of Korea
river deltas, sloping plains and rugged mountains
The Arctic tundra is a treeless world where
becomes sparser and less diverse, forming a
by plant roots. Paradoxically, however, the
and streams – wetlands rich in shorebird prey.
and China, staging shorebirds turn invertebrate
of Alaska and Siberia lie silent, shrouded in a
brutal winter winds and shallow soils restrict the
barren mosaic with frost-shattered stones. Each
combined effect of permafrost and six to
When the first shorebird migrants arrive
prey into fat before embarking north. The fat they
mantle of snow and ice. As the sun swings farther
growth of plants. This world of dwarf vegetation,
spring, this cold, stunted world beckons to the
ten months of snow produces a bonanza for
from the Yellow Sea, the tundra has just started to
accumulate in the Yellow Sea fuels not only the
north above the Arctic horizon, the white blanket
however, can be surprisingly rich. Mosses,
shorebirds departing from the Yellow Sea, calling
breeding shorebirds. When the snow recedes
emerge from its icy winter shell. Cold temperatures
final leg of their long migration to the Arctic, but
starts to soften beneath the relentless assault of
lichens, sedges, forbs and prostrate shrubs
them back to the realm of their birth.
each spring, the draining melt-water is trapped
retard snow melt, and spring storms often drop
also serves as an insurance policy in case severe
lengthening days. Soon, the immaculate white
produce a thick, spongy carpet from which the
In much of the Arctic, the thin layer of
by the permafrost within the narrow band of
fresh snow on the recently exposed tundra.
weather makes it difficult to feed once they arrive
landscape is dotted with small dark patches
miniature branches of dwarf willow and birch
tundra vegetation rests on an impervious mass
active soil and vegetation that manages to thaw.
How do shorebirds survive these inclement
on the breeding grounds.
Snow melting in the Siberian region of Chukotka at the end of May.
64
The tundra 65
Invisible connec tions
During mild springs, when winds are gentle
spend the non-breeding season in North or South
For the next few weeks, chicks grow at a
After the adults vanish into the austral sky,
and the Arctic sunlight is reflected from the
America have breeding ranges that extend from
prodigious rate. When first hatched, they are but
some juveniles linger on the tundra and around
snowy landscape in a shimmer of blazing white,
the Alaskan tundra into north-eastern Siberia.
tiny balls of down atop grotesquely large legs and
inland wetlands, but soon, most grow comfortable
shorebirds trickle back to their breeding grounds.
From the other direction, some populations of
feet, endearingly awkward in both form and gait.
in the marine environment. In Alaska, between
During stormy springs, however, shorebird
Dunlin and Bar-tailed Godwit move annually from
Within a week, however, they begin to assume
bouts of feeding on tidally exposed mudflats,
arrival can be far more spectacular. Severe
Australasia and Asia to breed in Alaska.
the proportions of their parents. At the same time,
young godwits destined for New Zealand loaf on
weather at higher latitudes may temporarily pin
These geographic exchanges produce
their downy garb gradually gives way to a fresh
offshore sandbars, while young Dunlin bound for
northbound migrants between their staging and
some surprising vignettes. On Belyaka Spit
juvenile plumage, crisply patterned with distinct
the Orient roost on tilting islands of peat eroded
breeding grounds. When storms persist, these
in Chukotka, Rock Sandpipers from North
feather edgings that distinguish them from their
from the sloughing edge of the continent. Like
aggregations build in number and diversity,
America may perform flight displays next to
parents. This period of growth and development
their parents before them, their attention turns
crowding eager waders at the threshold of their
Spoon-billed Sandpipers that spent the winter in
is a time of great risk for shorebird chicks. The
inevitably to the south as Arctic days shorten and
destination. When the weather breaks at last
Bangladesh. On the Yukon-Kuskokwim Delta in
tundra is alive with potential predators – foxes,
the September equinox comes and goes. Skies
Alaska, Bar-tailed Godwits recently arrived from
weasels, minks, hawks, falcons, cranes, jaegers,
through which they have never flown and lands
northward in a burst of excitement. Plovers,
the Yellow Sea may join Black Turnstones from
gulls and owls. In some years, very few young
which they have never seen beckon ever more
godwits, turnstones and sandpipers streak
California to mob Peregrine Falcons from Latin
survive to reach the next great transition of their
urgently, irresistibly calling the young shorebirds
so, too, does the migratory hiatus. Flocks surge
A Pacific Golden Plover enters the world.
toward familiar haunts, careening in tattered,
lay the eggs, but the task of incubation belongs
America. On Alaska’s North Slope, Asian Dunlin
life – from an earthbound existence to a life of
away from the tundra and continental shorelines,
wind-blown skeins above the thawing tundra.
to the drab males. Species that rely heavily on
may nest near Stilt, Semipalmated and White-
winged freedom. For those that survive, their first
and on to their great southbound odyssey. When
Adorned in festive breeding plumage, banking
the Yellow Sea during migration, however, tend
rumped Sandpipers from Mexico, Suriname and
tentative flight may occur less than three weeks
at last they take wing and ascend above the sea
flocks dash and descend in a tumult of jet black,
to be more traditional once they arrive on the
Argentina, respectively.
after hatching, while tufts of down still decorate
to track the curve of the earth ever southward,
burnished rust, mottled grey and gleaming white.
breeding grounds. For example, in Bar-tailed
About a month after the arrival of migrant
their crown and nape. Rarely at first, but then
they are blessedly unaware that only a few will
The great frenzy of Arctic breeding erupts across
Godwits, Red and Great Knots, Dunlin and
birds in the Arctic, a second great burst of life
with increasing frequency and skill, the young
survive to return and complete the cycle, bringing
the tundra.
Spoon-billed Sandpipers, both parents share
animates the tundra. Beneath the whistles, trills
shorebirds take to the air.
forth new life in the Arctic.
incubation duties.
and croaks of breeding shorebirds, a faint buzzing
By the time the young shorebirds are
Soon after arriving, migrant shorebirds establish territories, form pairs and start nesting.
One of the great marvels of the Arctic
tremor arises. On warm days, that tremor grows
flying well, they may be on their own, abandoned
Nests are simply shallow scrapes in the low
spring is the stunning convergence of birds from
into a pervasive hum that seems to come from
suddenly by parents with different priorities.
vegetation, lined with fragments of lichen, moss,
widely scattered origins. Nowhere is this more
everywhere at once. Myriad insects emerge from
Adults quickly shed the responsibilities of
leaves and twigs. Although many nests have no
pronounced than at the northern end of the East
the wetlands, shedding larval skins and arising
parenthood, flying to the nearest deltas, bays
overhead cover at all, others are tucked beneath
Asian – Australasian Flyway, where shorebirds
as winged adults. Midges, mosquitoes, crane
and estuaries to prepare for migration. Juvenile
sprays of dwarf shrub or shaded by a thin lattice
from several different flyways gather to raise their
flies – hordes of tiny creatures begin to swarm
shorebirds, too, eventually move coastward, but
of interlaced sedges. Within these hidden bowls,
young. In the vicinity of the Bering Strait, between
over and above the tundra. At about the same
in their own time. Even in those species where
most shorebirds lay a clutch of four eggs, but
the Siberian autonomous region of Chukotka to
time, the first shorebird chicks start to break
adults and juveniles feed together along northern
they exhibit a great diversity of parental care. The
the west and Alaska to the east, birds from South
out of eggs, their wet skins quickly drying to
shorelines for a while, the adults usually depart
males of some species, such as Sharp-tailed
America and the Pacific Islands can be found
reveal exquisitely patterned down. Within hours
first, leaving the young shorebirds to prepare for
and Curlew Sandpipers, mate with more than
mingling in the same wetlands as birds from
of hatching, they are mobile, leaving the nest
and embark on their first great migration alone.
one female, and do not assist in the incubation of
Australia and New Zealand. At least six species
and actively foraging for their own food – newly
eggs. In other species, such as the phalaropes,
of sandpipers, including Rock, Western, Baird’s,
hatched shorebirds scampering about after
the larger and more brightly plumaged females
Pectoral, Buff-breasted and Semipalmated, that
newly emerged insects.
A Great Knot on its nest in the tundra.
No warm-blooded creature, not even a predator like this Rough-legged Buzzard chick, can escape mosquito attacks on the tundra.
66
The tundra 67
Invisible connec tions
Brown when the snow first melts, bright green later in the season – the variation in tundra landscapes is immense; from alpine tundra in Eastern Siberia near Anadyr (left) to the vast coastal plains of the Yukon-Kuskokwim Delta in Alaska (below).
68
The tundra 69
Invisible connec tions Throughout the Arctic the sun never quite dips below the horizon during the brief shorebird breeding season. In Alaska the long days and diverse wetlands combine to create a shorebird paradise, rich in insect prey. As a result, Alaska supports the highest density and diversity of breeding shorebirds in North America. More than 70 species of shorebirds have occurred in Alaska, and 37 breed regularly in the state, including Ruddy Turnstone (below) and Pacific Golden Plover (far below). Some of the richest habitats are the coastal wetlands of western and northern Alaska. After nesting, adult and juvenile shorebirds often have only a short journey to nearby shores where they gather in vast flocks to prepare to migrate south (right).
70
Invisible connec tions
The tundra 71 All of the world’s Great Knots breed in a very limited area of Eastern Siberia, nesting on the tops and upper slopes of dry rocky hills. Aerial displays are common early in the breeding season, but once incubation starts, pairs behave very secretively. The birds’ camouflage is so effective that it is almost impossible to find their nests, which are hidden in lichen newly emerged from under the snow.
72
Invisible connec tions
On a rocky hilltop in Siberia a Great Knot (below) calls to warn its chicks of danger. The downy chick (centre and upper right) is about two weeks old and well camouflaged between the rocks and lichen, especially when it stays still. Its wing feathers are growing very quickly. In another week most of its down will have been replaced by juvenile plumage. The slightly older chick (lower right) is already able to fly.
The tundra 73
74
Invisible connec tions
Soon after they arrive on the tundra, Red Knots start their courtship displays. Adult Grey Plovers use a variety of distraction displays to lure predators away from their nests (upper right). Newly hatched chicks (lower right) may leave the nest within a few hours, but still need to be brooded regularly by their parents for several days after hatching.
The tundra 75
76
The tundra 77
Invisible connec tions
After flying more than 10 000 kilometres to the tundra, Bar-tailed Godwit males have no time to rest. To secure a mate they perform extensive display flights and sometimes have fierce fights with territorial neighbours. The male (above) and female godwits share incubation duties for about three weeks. Once the chicks have hatched (right), both parents also tend the brood.
78
Invisible connec tions
The tundra 79 Once the snow starts to melt, the song of breeding Dunlin resounds over the tundra (facing page). Four weeks later, the first chicks hatch (left). Within a few weeks of hatching, they can fly. Juvenile Dunlin (below) will undertake their first southbound migration without parental guidance.
80
The tundra 81
Invisible connec tions Not all shorebirds breeding in Siberia or Alaska migrate via the East Asian – Australasian Flyway through the Yellow Sea. Although Rock Sandpipers breed on both sides of the Bering Strait in Alaska and Siberia, most spend the non-breeding season on the West coast of North America from southern Alaska to California. A few occur as far west as Japan. This Rock Sandpiper (below left) has just arrived on the breeding grounds in Alaska; the upraised wings are part of its display to attract a mate. The Black Turnstone on its nest (below) is limited to North America. Black Turnstones breed along the coasts of the Bering and Chukchi Seas in Alaska and migrate to the Pacific coast from Alaska to Baja California for the rest of the year. Long-billed Dowitchers (above right), Western Sandpipers (near lower right) and Pectoral Sandpipers (far lower right) breed in the tundra of Alaska and Siberia. After the breeding season, birds nesting in Siberia join those in Alaska to migrate south via several different American flyways. Long-billed Dowitchers reach Central America, while some Western Sandpipers move as far as northern South America. Pectoral Sandpipers continue south all the way to Patagonia and are also regularly observed in coastal and inland Australia. The route they take to cover this long distance remains to be discovered.
82
Invisible connec tions
The complex patterns of the downy young of shorebirds differ considerably between species, reflecting both their ancestry and their nesting habitat. Despite all the variation in appearance, these patterns have a common function, disrupting the outline of birds so that it is difficult for predators to find them. Yet despite this cryptic patterning and the vast scale of the arctic landscape, huge numbers of shorebird chicks fall prey to predators such as Arctic Fox and Red Fox. Shown here are Great Knot (upper left), Whimbrel (upper right), Pacific Golden Plover (centre left) and Ringed Plover (centre right).
The tundra 83
84
The tundra 85
Invisible connec tions Even brightly coloured shorebirds such as Ruddy Turnstone (left) and Red Knot (below) are nearly invisible in the tundra vegetation when they sit motionless on their eggs. The numerous berries that ripen in the summer provide food for young and adult birds. But the arctic summer is very short, and soon the first snow will cover this rich harvest. Berries frozen over winter provide important support for next year’s arriving shorebirds.
86
Invisible connec tions
A southern holiday? 87
5 A southern holiday? Danny Rogers As the Arctic summer ends, shorebirds leave
non-breeding season in warm tropical regions.
question that still perplexes shorebird biologists:
exposes rich feeding areas which can be several
where shorebirds often have to share their
Wherever shorebirds choose to spend
their breeding grounds and head south. Some
The cost of living is cheap in the tropics, where
why do so many shorebirds migrate so far?
kilometres wide. The tropical coast of northern
habitats with urbanised human populations.
the non-breeding season, they face the same
species migrate no further than cool temperate
they do not need to invest much energy in
The highest numbers and diversity of
Australia
geographical
Furthermore, not all tidal flats are of equal value
tasks. They need to survive until the next
regions in the northern hemisphere; Grey Plover
keeping warm. Remarkably, some shorebirds fly
migratory shorebirds, especially of those species
requirements well, and includes some of the
to shorebirds; some are food-rich, and used by
breeding season, and they need to get into
that remain in Korea are an example. If they can
further still, bypassing the warm tropics and
that migrate furthest south, are found in extensive
greatest shorebird sites in the world – Eighty Mile
tens of thousands of shorebirds, while others
suitable physical condition to migrate north
survive the coldest periods of winter there, they
eventually coming to a stop in temperate non-
tidal flat systems. The geographical conditions
Beach, Roebuck Bay and the Gulf of Carpentaria.
can be quite poor. Shorebird biologists are
when the time comes. They also need to moult:
have a head-start when the time comes to return
breeding
southern
suitable for formation of such tidal flats are not
Extensive tidal flats are less common elsewhere
repeatedly struck by the relative importance of a
a natural process in which newly grown plumage
to the breeding grounds. Many species, however,
hemisphere, half a world away from the breeding
common, but in low-lying regions where gradients
in Australia and New Zealand, being confined to
small number of sites to global populations of
pushes out and replaces old, worn feathers.
continue south, via the Yellow Sea, to spend their
areas to which they will have to return. It is a
are small and tidal ranges are high, low tide
some estuary systems and other embayments
shorebirds.
Adult shorebirds need to replace their flight
grounds
deep
in
the
satisfies
these
A large shorebird roost at high tide in Roebuck Bay, north-west Australia.
88
Invisible connec tions
A southern holiday? 89
feathers once every year, and this is almost
unison. It is a sight that never fails to inspire bird
of finding roosts that humans rarely visit. Human
costs of one flight-feather moult, two body-
invariably done on the non-breeding grounds.
watchers, and almost always succeeds in baffling
disturbance at many sites is increasing as
feather moults and a near-doubling of mass as
The gradual replacement of these feathers takes
predators. Raptors may pursue such flocks for a
tourism, recreational demands and commercial
they prepare for the next migration. These energy
several months. It is energetically expensive,
short time in the hope of detaching a straggler,
developments compete for habitat. The presence
demands are so high that many shorebirds do
creating gaps in the wings which lower the
but they rarely succeed.
of people, even if they are only using beaches for
not succeed in meeting them; they remain ‘down-
efficiency of flight.
The escape flights of shorebirds are very
recreational purposes, can cause a great deal of
south’ when they should be busily nesting in the
Most adult shorebirds replace their head
effective, but come at a cost. They are
disturbance. It can even cause shorebirds to
northern hemisphere.
and body plumage twice a year. In part this is to
energetically demanding (far more so than the
abandon good feeding areas simply because
Many of the remaining birds are immature,
ensure the plumage continues to provide
steady-paced flight used when migrating), and
there are no adequate roost sites within reach.
and they also tend to belong to the larger species
adequate insulation. Head and body moults also
energy used avoiding predators cannot be
Such disturbances must be considered in
which mature more slowly. Most strikingly, they
serve
seasonal
invested in moult, or in building up fat stores in
management decisions about sites. In some
tend to be birds of tidal flats, as shorebird species
appearance of most shorebirds. The russet,
preparation for northward migration. Ideally,
cases they can be controlled with simple
that mainly use freshwater habitats grow up
measures such as restricting beach access,
much more quickly. This suggests there are
brown
to and
completely black
alter
markings
the
which
make
therefore, shorebirds should spend their time in
Panting Eastern Curlew.
Sleeping Bar-tailed Godwits.
shorebirds so difficult to see on their nests in the
very open situations. Here, predators will never
constructing hides from which the public can
complexities involved in the exploitation of the
tundra stand out like beacons on an open tidal
attack them as they have no hope of getting
view shorebirds, or by erecting signs to make the
food supplies of tidal flats. Perhaps prey is so
flat! Shorebirds begin to replace their breeding
replacement is completed within a month, and
energy
public aware that they should avoid disturbing
difficult to find in these habitats that only
plumage as soon as they arrive on the non-
the resultant non-breeding plumage is a much
However, very open situations have energy
conservation and predator avoidance are of
shorebirds. With carefully planned engineering, it
experienced shorebirds can find enough to build
breeding grounds. Most of the body-feather
plainer affair, typically greyish above and whitish
costs of their own, as they expose shorebirds to
particular importance to the behaviour of coastal
is even possible to construct artificial shorebird
up the stores needed for migration.
below. It blends in well with the colour of mudflats
the elements. In relatively cool non-breeding
shorebirds when the tide is high. In these
roosts. In other cases legislation to restrict
in the heat-haze and makes shorebirds less
areas such as New Zealand, the chill factor
conditions, when the tidal flats are immersed,
disturbance at key feeding or roosting areas
conspicuous to predators.
caused by strong winds increases the costs of
feeding is impossible. Shorebirds are forced to
must be considered.
maintaining
it
nearby sites, known as roosts, where they
Around February, towards the end of the
non-breeding shorebirds are at risk from
advantageous for shorebirds to remain active (if
attempt to stay safe while avoiding unnecessary
non-breeding season, adult migratory shorebirds
predators,
Such
they are feeding) to generate body heat, or (if
energy expenditure. Finding suitably open sites
step up preparations for the return migration to
predators typically attempt to catch shorebirds
they are sleeping) to pack together in tight flocks
is challenging, as land above the high tide mark
their breeding grounds. Once again, they start
by surprise when they are on the ground.
which act as a windbreak. In hot non-breeding
often has vegetation or buildings that can be
body moult – this time, attaining the brightly
Shorebirds fly fast, and if they have time to take
areas, such as tropical north-western Australia,
used as cover by approaching predators. Birds
coloured plumage that will serve the multiple
off and reach top speed, they are unlikely to be
exposure to direct solar radiation is a threat, as it
of prey use this kind of cover skilfully as they try
purposes of attracting a mate, keeping them
captured. It is also beneficial to feed and roost in
exposes shorebirds to potentially lethal high
to burst into a roosting shorebird flock at high
warm at high latitudes and blending in with the
flocks, as there will then be many pairs of
temperatures.
several
speed. The need to roost in suitable microclimates
ground on which they will nest. At about the
shorebird eyes scanning for danger. If just one
behavioural ploys to avoid overheating, including
makes the search for a roost site still more
same time, they also begin to gain weight, as
shorebird sees approaching danger, it will
panting and raising selected feathers to disperse
difficult. At some sites shorebirds need to fly long
they build the fat and protein stores needed to
immediately take off, making an alarm call that
body heat. Careful selection of microhabitat is
distances to find suitable roosts, commuting to
fuel the long flight ahead.
springs all of its companions into action. The
even more important. For example, when
30–60 kilometres per day between roosting and
flock gains height as quickly as possible, its
shorebirds stand in shallow water, or on wet
feeding areas.
apparent colour flickering from white to dark as
substrates, they can dissipate body heat through
every bird twists and turns in extraordinary
their feet into the surrounding water.
Even in cryptic non-breeding plumage,
Moulted godwit feathers on the mudflats.
especially
birds
of
prey.
The
close without being detected.
body
temperature,
Shorebirds
making
have
conflicting
demands
of
Thus, for an adult shorebird, the nonbreeding season hardly qualifies as a holiday.
In many non-breeding and staging areas,
The entire period involves steep energy demands:
shorebirds at high tide face the additional burden
the everyday costs of survival and the additional
Bathing Common Greenshank.
90
Invisible connec tions
Roebuck Bay, north-west Australia, declared a Ramsar site in 1990, with striking scenery and vast tidal flats, supports tens of thousands of birds. Yet even here, space with a cool microclimate is limited at high tide, and shorebirds roost close together in shallow water or on wet sand at the waters edge. The nearby town of Broome is expanding rapidly and, as there is no management plan for the Bay, this crucially important bird habitat is still not secure.
A southern holiday? 91
92
Invisible connec tions
A southern holiday? 93
Most tidal flats in south-eastern Australia are rather small, and are impacted by commercial and recreational activities. Point Cook (left) is the closest shorebird site to Melbourne; other sites nearer to the city have been lost to development. Corner Inlet (this page) is an exception: a relatively undisturbed national park, used by many shorebirds despite the presence of nearby industry. However, the spread of the introduced weed Spartina has caused loss of some shorebird roosts and feeding areas.
94
A southern holiday? 95
Invisible connec tions Red Knots and Bar-tailed Godwits are the only Arctic breeding shorebirds to reach New Zealand in large numbers. While pressure on tidal flats from industry here has been small, encroachment of mangroves and weeds threatens some roosts. The only fully protected reserve is Farewell Spit, a dramatic, windswept 30-kilometre long sandspit at the northern tip of the South Island, which holds 30–40 000 shorebirds through the year. The Red Knots and Bar-tailed Godwits (below) are at Farewell Spit in late March. Most are nearly ready to set out on northward migration, with extensive breeding plumage and enormous fat stores creating a rounded body shape. This flock also includes some immature birds of both species, still in non-breeding plumage and with a relatively slim body profile. These young birds have not fuelled up for a long northward migration, and will remain in New Zealand through the next southern winter.
96
A southern holiday? 97
Invisible connec tions Pied Oystercatchers, Red Knots and Bar-tailed Godwits (above left) endure a squall in New Zealand, facing the wind to prevent cold rain permeating their plumage. In tropical north-west Australia, shorebirds use very different behavioural ploys to avoid overheating. These Asian Dowitchers (below) are selectively raising their back feathers to dissipate body heat. Panting is another cooling method, being used by these Whimbrel (right) because limited roost availability has forced the birds to land on hot, dry rocks.
98
Invisible connec tions
Shorebirds preen to maintain plumage condition. Bathing (as in this Bar-tailed Godwit) helps dislodge dirt and possibly also ectoparasites. All shorebirds secrete a special wax from a gland just above the tail. Preen wax is carefully and regularly spread over all the plumage (as shown by this Great Knot) as it helps to repel water and feather-digesting bacteria. Most shorebirds do not migrate until they are at least two years old. Immature birds remain in the southern hemisphere. These young birds (right) are sharing Roebuck Bay with resident Black-winged Stilts, Silver Gulls and a Gull-billed Tern.
A southern holiday? 99
100
A southern holiday? 101
Invisible connec tions
This White-bellied Sea Eagle carrying a sea-snake on Eighty Mile Beach ignores the roosting flock (above left), but the Eurasian Hobby at the Geum Estuary, Korea (below left), is actively hunting shorebirds. Gaps in the wings, and shed feathers at a roost, are an indication that it is moulting season. Annual moults are essential to replace worn plumage, but they temporarily reduce flight performance, hence increasing the challenge of escaping from predators.
102
A southern holiday? 103
Invisible connec tions Residents and migrants share habitats in north-west Australia: Red Kangaroo with Common Greenshank; resident Sooty Oystercatcher and Lesser Crested Terns with migrant Grey-tailed Tattlers, Terek Sandpipers and others; Australian Pelican with a mixed flock of migrants. The Masked Lapwing (right) is also an Australian resident – perhaps the unusual wing spurs of this species would not have evolved if it needed to optimise flight performance for longdistance migration.
104
A southern holiday? 105
Invisible connec tions
Disturbance at high tide roosts, such as that caused by this couple and their dog, costs shorebirds vital energy by forcing them to make escape flights. Public education can change people’s behaviour so that shorebirds can relax at high tide, but in some cases legislation may be needed to protect sides where shorebirds roost.
106 Invisible connec tions
Tidal flat specialists 107
6 Roosting shorebirds, mostly Great Knots and Bar-tailed Godwits.
Tidal flat specialists Danny Rogers & Jae-Sang Hong At first glance, tidal flats can seem bleak and
ostracods. Tentacle-like appendages protrude
necessary to take some sediment and wash it
All ecosystems need the fundamentals of
organisms that are far too small to be seen with
also influence the suitability of tidal flats for
lifeless habitats. Uniformly grey or brown, they
from burrows. But they are not all tentacles. They
through a sieve. With the sand and mud gone,
water, sunlight and nutrients, and tidal flats have
the naked eye. Nevertheless, their proliferation
benthic animals. The interactions between these
run to the tide edge or horizon, uninterrupted by
may be siphons of shellfish, sucking in water
the residue may reveal astonishing numbers of
at least two of these in abundance. At low tide,
can be seen in the course of a low tide – they are
variables are highly complex. While we do not
any landmarks larger than puddles. Yet, a closer
from puddles or detritus from the ground surface;
animals that seldom or never poke their heads
the passage of sunlight is not interrupted by
responsible for the brown or greenish tinge on
fully understand why some tidal flats have much
look will reveal how rich in life they are, especially
the impossibly slender arms of feeding brittle
(or tails) above the surface when the tide is low.
turbid waters yet the substrate remains moist
the surface of tidal flats.
richer benthic fauna than others, we do know
if you remain motionless for a few minutes. First
stars; heads of predatory bristle-worms, actively
A great diversity of animals is involved, all having
enough to support life. These conditions on the
Plants and the detritus left after their death
that simply depositing mud in front of a new
you may notice marine snails gliding over the
chasing tiny prey; or you may be looking at the
specialisations that enable them to live in this
surface of tidal flats are perfect for photosynthesis
are the major part of the basis of a complex food
seawall does not instantly create a tidal flat where
surface, and a variety of burrow openings –
sticky inside-out gut of a sipunculid worm,
challenging environment. Submerged by food-
– the chain of chemical reactions by which plants
web. Other nutrients may be brought in by
shorebirds can find food.
some tiny, some big enough to stick your arm
carefully being unrolled to entrap detritus before
filled waters for part of the day, they are left high
build up complex organic molecules from the
currents from the sea, or washed in from the
Benthos abundance and diversity also
down. If you wait longer, more and more life will
being drawn back into the body.
and dry at other times. They may be exposed to
basic ingredients of water, carbon dioxide and
land. It may be the inflow of terrestrial nutrients
vary on very broad geographical scales. There is
assume that it is safe and start to emerge. Tiny
To truly appreciate the abundant diversity
freezing temperatures when it is cold, to
sunlight. In addition to conspicuous intertidal
that explains why so many of the most productive
a strong trend for intertidal benthos to be more
crustaceans dart across puddles – possibly
of tiny animals and plants living in the sediment
desiccation if it is hot, to osmotic shock if it rains
plants such as mangroves and sea-grasses, the
tidal flats in the world occur in estuaries. Local
diverse in tropical regions than at high latitudes:
glowing electric blue at night if they are
of a tidal flat, collectively known as benthos, it is
and to predation when shorebirds are present.
food-producers include diatoms, single-celled
sediments, current velocities and wave energy
for example, benthos surveys of similar scale
108 Invisible connec tions
Tidal flat specialists 109
used by the plovers, and by other shorebirds
has a much longer down-curved bill, and with
which are emptied daily by the shell-fishers and
to support a fishing community of about 20 000
Yet many species of migrant shorebirds
such as curlews. They simply wait and scan, and
careful, neck-twisting probes, this can be used
are sometimes also raided by Whimbrel. Bivalves
people. The ongoing reclamation at Saemangeum
have no other choice. They are exclusively
when they see a prey item on the surface of the
to extract large crabs from very deep burrows.
such as cockles are harvested even more heavily,
has collapsed this fishery, with fewer than 1000
specialised to feed on tidal flats while staging on
mud, they chase and catch it. The visual clues
The crabs themselves try to avoid this fate by
in general being captured by hand with traditional
people now able to eke out some income from the
migration, and cannot feed effectively in other
they detect may be very subtle. For example, a
burrowing ever deeper, and even by hanging
methods. The hand-tools used to locate buried
remaining shellfish stocks. Many have fallen on
habitats such as the freshwater wetlands and
number
upside down from the roof of their burrows.
bivalves vary enormously from estuary to estuary
hard times. Lacking safety nets provided by
agricultural lands that typically result from
and
– due in part to cultural evolution, but also
government or family, shorebirds displaced by the
reclamation projects. We must never forget that
in tidal flats, but a person can spend a day walking
abundant benthos-hunters are humans. People
because the effectiveness of different tools is
Saemangeum reclamation are likely to face even
tidal flats are irreplaceable for these shorebirds.
over tidal flats without actually seeing one, as
and shorebirds can be seen in close proximity at
influenced by substrate type. Like shorebirds,
greater difficulties. Moving to other tidal flats is
they spend most of their life concealed in burrows.
low tide along hundreds of kilometres of the
humans find that foraging on tidal flats requires a
not a simple option, as about 50% of the tidal
However, they do occasionally extrude their rear
Yellow Sea coast. Much of the benthos collected
good deal of specialisation.
flats of the Yellow Sea have already been
end to the burrow entrance in order to defecate.
by people is eaten locally, with many regional
This specialisation comes with a price. It
reclaimed, and those remaining are already likely
Cautious and brief though this vulnerable moment
delicacies as a result. Still more is exported to
puts both people and shorebirds at risk when tidal
to be supporting large numbers of birds and close
is, it can be exploited by shorebirds such as Grey
seafood restaurants, especially in China. Simple
flats are lost. The tidal flats at Saemangeum used
to their shorebird carrying capacity.
revealed the presence of 182 benthic species in
Plovers, which catch worms they detect by seeing
crab traps are a common sight on the tidal flats:
the Dutch Wadden Sea, 411 species on the more
tiny outflows of water from the mouth of their
lengths of bisected plastic guttering, weighed
diverse west coast of South Korea, and well over
burrows. Some shorebird species can detect
down with sandbags. Crabs are unable to climb
600 species in Roebuck Bay, north-western
prey without any visual cues at all, relying on
out of the guttering once they have fallen in, so
Australia. On the other hand, benthos is more
other, highly developed senses. The Red Knot,
walk along it to be trapped in collection buckets,
abundant at high latitudes, and the benthic
for example, pecks the surface rapidly, displacing
animals present are generally larger than those in
pore water. Specialised receptors in the bill tip
the tropics. In the richest sites so far assessed in
then detect such subtle differentials in the
the Yellow Sea, there were an average of about
resistance encountered by the displaced pore
3000 animals and 1 kilogram of biomass per
water that Red Knots can locate buried hard
square metre; some clam beds may have
objects (such as bivalves, their favoured prey) up
biomass values of over 10 kilograms. Not all of
to 5 cm away.
of
shorebird
species
hunt
large
bristleworms. These worms are often abundant
Low tide on a mudflat.
these animals are suitable prey for shorebirds,
The capture of benthic prey is also a
and there is much to be learned about shorebird
challenge; it can take a long time and a lot of
diets in this Flyway.
effort to pull a reluctant invertebrate from a deep
Although the invertebrate animals of
hole. Crabs are easy to see on the surface, but
mudflats can be very abundant, shorebirds
when they venture to the surface to feed, they
require specialisations to feed upon them. They
stay close to the entrances of their deep and
use many different techniques to find their
complex burrows. Crab capture often requires a
preferred prey. Efficiency is essential because
lunge down the burrow mouth to catch crabs
time is limited: shorebirds cannot dive for food,
before they have scuttled to safe depths – a task
so they can only forage on tidal flats when the
for which the long up-curved bill of the Terek
tide is low. Perhaps the simplest approach is that
Sandpiper is well adapted. The Eastern Curlew
Perhaps
the
most
widespread
A shellfish collector in South Korea cleans the catch of the day.
Extensive intertidal mudflats are essential for shorebird flyways. Such mudflats are very rare; they only occur where a high tidal range combines with a soft sediment shoreline. The white dots mark the world’s most important areas for shorebirds: 1. Mudflats of the northern Yellow Sea 2. Roebuck Bay and Eighty Mile Beach, Australia 3. Ganges– Brahmaputra Delta, Bangladesh 4. Shores around the Persian Gulf 5. Copper River Delta, Alaska 6. Yukon-Kuskokwim Delta, Alaska 7. James Bay, Canada 8. Bay of Fundy, Canada 9. Mudflats on the foreshores of the Guyanas 10. Tierra del Fuego 11. Archipelago dos Bijagos, Guinea-Bissau 12. Banc d’Arguin, Mauritania 13. The large estuaries of Great Britain 14. Danish, German and Dutch Wadden Sea
increasing tidal amplitude
Increasing tidal range
110 Invisible connec tions
Tidal flat specialists 111 Plants like these mangroves, sea-grasses and the green film of algae on the mud surface are the basis of the tidal flat food chain. As primary producers they convert sunlight, water and nutrients into food. Hungry shorebirds will start feeding in the first areas to be exposed after high tide – here, it is at the edge of the mangroves.
112 Invisible connec tions
Tidal flat specialists 113 Biologists need to sieve mud samples to find invertebrates hidden below the surface. Shorebirds such as Grey Plovers have keener eyes and sharper reflexes, enabling them to locate prey by spotting subtle cues on the surface of the mud, such as wormcasts being extruded from burrows.
Tidal flat specialists 115
114 Invisible connec tions
Great Knots (left) and Red Knots (above) specialise in hunting bivalves, targeting small individuals that are swallowed whole and crushed in the gizzard. Such small specimens are often localised and are incapable of running away – so knots gather in dense flocks when they find a rich feeding patch. Large bivalves are usually too big to be swallowed. The Dunlin (right) has found an unusual opportunity, and is eating the flesh from a dead bivalve washed ashore.
Tidal flat specialists 117
116 Invisible connec tions
Polychaetes (marine worms) are abundant and diverse on tidal flats. They lack indigestible shells or skeletons, making them an energy-packed meal favoured and easily swallowed by many small shorebird species, such as Dunlin (left), Red-necked Stint (upper right) and Spoon-billed Sandpiper (lower right).
118 Invisible connec tions
Tidal flat specialists 119 Curlew (left) and Whimbrel typically shake large crabs vigorously to dislodge their dangerous claws before swallowing the crab whole. In the Yellow Sea, fishermen also catch many crabs, and Whimbrel (below) sometimes inspect their traps in the hope of finding a free meal.
Tidal flat specialists 121
120 Invisible connec tions
Shorebird food is diverse. Here, a Common Greenshank (left) juggles a bristleworm; a Terek Sandpiper (right) manipulates a crab. The Grey-tailed Tattler (below) and Ruddy Turnstone (lower right) are both feeding opportunistically on stranded bivalves, which were gaping open as they died after the closure of the Saemangeum seawall.
Tidal flat specialists 123
122 Invisible connec tions
Shorebirds spread out when feeding to avoid interference from flock mates. A metre or two may suffice for birds such as Black-tailed Godwits (above), which use touch to locate buried worms and bivalves. Interference is a bigger problem for species that use sight to locate active surface-dwelling prey like crabs. Some species, like Whimbrel (left), aggressively defend feeding territories. Interference becomes more problematic for shorebirds when they are forced into smaller areas by habitat loss. The camera has frozen the action as one of the Black-tailed Godwits above produces a dropping. The energy-intensive lifestyle of shorebirds requires a lot of food. It needs to be digested quickly, so that birds can forage throughout the precious hours of low tide without being forced to pause by an over-full gizzard. As a result, prey items pass through foraging shorebirds quite quickly (often in 20–30 minutes). As the intake rate of food increases, so does the rate at which the residue is excreted; successfully foraging shorebirds may pass droppings every 2–3 minutes.
124 Invisible connec tions
International par tnerships 125
7 Godwits departing from Australia on northward migration.
International partnerships Phil Battley Just as the shorebird world is an international
done by fitting each captured bird with a uniquely
other researchers use combinations of different
southernmost extremities of South America,
the north-western corner of the Yellow Sea, but
Australia breed on the New Siberian Islands.
one, so too is the community of birdwatchers,
numbered metal ring on its leg. If ever that bird
colour-bands that can be ‘read’ with telescopes.
Africa and Australasia. Sophisticated captive
counts there do not approach the more than
Snow melt there is probably not until June, and
conservationists and researchers who seek to
was recaptured, its identity and place of capture
In this way, the movements of individual birds
facilities in the Netherlands have enabled detailed
150 000 Red Knots believed to migrate through
calculations showed the knots might still be able
unravel the mysteries of these birds and their
could be tracked.
become known.
experiments that revealed knots’ remote sensing
the Flyway. One reason these knots may be
to reach their breeding grounds if they could
global journeys. The birds themselves demand
In the 1990s, methods changed towards
Still, the East Asian – Australasian Flyway
ability when feeding, and studies in Africa and
‘missing’ is that surveys may not coincide with
refuel quickly in Asia. This depended on birds
this international approach, as no one country
those that did not require the recapture of birds.
may be the least understood and researched of
Siberia have evaluated the annual energy costs
peak migration times. For example, researchers
locating prey of much higher quality than they
hosts the entire life cycle of such species. This
With leg-flags (small, colourful plastic tags
the
Incredibly,
of staying warm throughout a flyway. Their
radio-tracking Red Knots in north-western
fed on in Australia. There is a parallel here with
fact constrains what researchers in any one
attached to the upper legs), and countries using
refuelling sites hosting tens of thousands of birds
shellfish-eating habits have been confirmed and
Australia found most of their birds were still there
knots from South America. These migrate north
country can discover, but provides a unique
their own unique colour, any birdwatcher spotting
continue to be discovered, and some of the
studied in Australia and New Zealand, and
in early May, almost a month after the birds were
through Delaware Bay on the east coast of the
opportunity for international collaborations to
a flagged bird could instantly know where it
world’s best studied species are still mysterious
thousands of birds have been banded or leg-
expected to have left!
United States, where they gorge on the eggs of
study the biology of the East Asian – Australasian
came from. The 63 000 shorebirds flagged in
in their migrations. Red Knots are the classic
flagged in the East Asian – Australasian Flyway.
Flyway’s amazing migrants.
north-western Australia, for example, have now
example of international shorebird research.
Nowhere is this more obvious than in the
yielded over 2000 re-sightings, and their pattern
efforts to map the movements of shorebirds throughout the Flyway. Traditionally, this was
world’s
shorebird
flyways.
The question then became: could these
Horseshoe Crabs. Just a few weeks of feeding
Despite this, we still do not know where
knots still reach the breeding grounds in time to
frantically there can allow the birds to fatten up
Different subspecies spread out from the high
most of the Red Knots in this Flyway refuel during
breed? After all, in May most other migrants are
again for their flight to the breeding grounds. It is
outlines the Flyway. More recently, some leg-
Arctic tundra to wintering grounds stretching
migration. The only area where good numbers
already refuelling in Asia, or even travelling to the
possible that Red Knots from Australia use a
flags have been engraved with numbers, and
from Europe, through the tropics, to the
have been found in Asia is Bohai Wan in China,
breeding grounds. Red Knots from north-western
similar strategy, concentrating in an as yet
126 Invisible connec tions
International par tnerships 127
undiscovered area where they can feed on rich,
catch migrating shorebirds for research. With
The East Asian – Australasian Flyway has
fat shellfish or other invertebrates.
decoys and a clap-net set in a patch of
also been the subject of ambitious high-tech
There is a dark side to the Delaware Bay
unvegetated mud at the saltmarsh edge, the bird
migration studies. In the late 1990s, the
story, however. The Horseshoe Crabs that lay
catchers listen for the call of a passing migrant.
Queensland Wader Study Group teamed up with
their eggs on the beaches are now commercially
Expertly manipulating a small bamboo whistle,
the Wild Bird Society of Japan to satellite track
over-harvested. This has caused the numbers of
they imitate any shorebirds they hear, luring them
the world’s largest shorebird, the Eastern Curlew.
eggs on the beaches to drop and the numbers of
towards the decoys. At this point the net is pulled,
They used backpack-mounted transmitters to
knots to plummet. The main subspecies of Red
flinging itself into the birds’ flight path. This has
track curlews migrating north from the east coast
Knot that uses this region declined from 150 000
proved a highly effective way to catch birds, all of
of Australia, and showed that curlews made
individuals to fewer than 20 000 birds in less than
which are banded with individually numbered
massive flights from Australia to the Philippines,
two decades. This or a similar scenario could be
metal rings and given the local black over white
and probably to China, Japan and South Korea.
being played out in the East Asian – Australasian
leg-flags. Sightings of these birds around the
These flights may have been as long as
Flyway without it even being realised. Discovering
Yellow Sea and the Flyway help to piece together
7500 kilometres and, until recently, were among
where
occur,
their complex migratory movements. University
the longest non-stop flights known.
understanding why those areas are chosen and
researchers have also been surveying the
ensuring the long-term availability of those sites
shorebirds using the ever-diminishing tidal flats in
are crucial if the future of these birds is to be
the Yellow Sea, documenting that shorebirds are
Alaska. In 2007, the Pacific Shorebird Migration
safeguarded.
just not able to cope with the effects of the current
Project, a collaboration of shorebird biologists
the
Flyway’s
shorebirds
At the local level, throughout the Flyway
reclamations.
That record has now been beaten by BarEastern Curlew, the world’s largest shorebird.
tailed Godwits from New Zealand which breed in
Such partnerships play a key role in developing
from the United States and Australasia, used
knowledge and skills through the Flyway.
satellite telemetry to track the movements of
there are groups of dedicated people doing just
Further north in the Yellow Sea, on the
this. At Chongming Dongtan Nature Reserve at
border with the Democratic Peoples’ Republic of
Joint international endeavours are also
godwits from New Zealand. The team caught
the mouth of the Yangtze River, Chinese
Korea, Yalu Jiang National Nature Reserve hosts
documenting the numbers and origins of
birds before migration and deployed small
researchers have co-opted former bird hunters to
tens of thousands of refuelling shorebirds,
shorebirds passing through Saemangeum in
internal satellite transmitters. In mid-March the
including the largest Bar-tailed Godwit flocks
South Korea. From 2006 to 2008 the Australasian
first birds took off. After a week of non-stop flight,
known on migration. Most of the godwits present
Wader Studies Group joined with Birds Korea to
these godwits made landfall in China and South
in April will be from New Zealand, and often the
survey Saemangeum through the April–May
Korea on the shorelines of the Yellow Sea.
coastline will be frequented by New Zealand
migration period. These surveys complement
But the story did not end there. The
back at her wintering site in New Zealand she
feats that migratory shorebirds undertake. Her
birdwatchers. The reason for this? Yalu Jiang has
earlier work that established the Saemangeum
transmitters worked so well that four birds could
had made the longest non-stop migratory flight
flight, and those of other Bar-tailed Godwits,
a formal relationship with the Miranda Naturalists’
region to be arguably the single most important
be tracked returning from Alaska to the southern
ever documented – 11 700 kilometres.
reinforce the critical importance of those few,
Trust in New Zealand, and in most years staff from
stopover site for shorebirds in the Yellow Sea.
hemisphere. One of these birds, E7, was about
This was a flight of staggering magnitude,
Yalu Jiang will journey to New Zealand, or
Now, however, they are documenting its demise.
to fly her way into the history books. She had
crossing the largest ocean in the world. She was
the
volunteers from Miranda join forces with Yalu Jiang
With the closure of a 33-kilometre seawall in
already set the record on northward migration,
tracked for 29 000 kilometres over six months,
conservation.
staff to survey the reserve and catch shorebirds.
2006, Saemangeum as a natural system ceased
flying 10 300 kilometres from Miranda in New
although only 21 days of that period were spent
to exist. Shorebirds arriving there from Australasia,
Zealand to Yalu Jiang National Nature Reserve in
in flight, and she had set foot in only three
South-East Asia and China found most tidal flats
China. Returning to New Zealand, she left the
countries in that time. E7 made the global
to be parched, cracked wastelands, rather than
Yukon Delta in Alaska on 31 August and flew
headlines, revealing hitherto invisible connections
the rich, vibrant flats that were formerly there.
south for the next eight days. When she arrived
to all, and astounding the world with the incredible
Red Knot, an enigma of the East Asian – Australasian Flyway.
As a joint project, Chinese and New Zealand scientists prepare to catch migrating shorebirds in mist-nets at Yalu Jiang, China.
distant tidal flats that these birds rely on around globe,
and
the
imperative
for
their
128 Invisible connec tions
International par tnerships 129 The migration of this Bar-tailed Godwit (left) will link many countries. Unique combinations of colourbands allow birds to be re-sighted without being recaptured, providing information on movements, survival rates and population dynamics. Plastic leg-flags are also used to track migration routes. Yellow indicates capture in north-west Australia, orange in south-east Australia, black over white in China and lime green in Eastern Siberia. Each bird is given a numbered metal band, and data on its weight, measurements and plumage collected to assess the sex of the bird and its readiness to migrate. Researchers are increasingly forming international alliances to study migratory shorebirds, but these efforts need to be matched at government level to ensure that the birds’ needs for feeding and roosting sites are met at every stage of their migratory journeys.
130 Invisible connec tions
International par tnerships 131
At Chongming Dongtan Nature Reserve, north of Shanghai, former hunters now use their traditional methods to catch shorebirds for research. Using a bamboo whistle, the hunter imitates bird calls to lure birds flying overhead towards his ‘flock’ of decoys, then the clap net is pulled across the birds’ flight path.
International par tnerships 133
132 Invisible connec tions
Researchers catch roosting shorebirds by firing nets over them. In hot places like north-west Australia the net then has to be covered to prevent overheating before birds are removed. Many volunteers are needed to band and measure the birds speedily. As the birds migrate through the Flyway, volunteers in Korea and China look for colour-marked birds at the staging sites.
International par tnerships 135
134 Invisible connec tions
In 2007, using a pioneering technique, this female Bar-tailed Godwit (below, with a black leg flag and the aerial showing) called ‘E7’ was fitted with a satellite transmitter in New Zealand as part of a research project by the US Geological Survey’s Alaska Science Center. The story of her migratory journey could be followed daily on the USGS website and made global headlines. E7 made a 10 300-kilometre direct flight from New Zealand to China and, even more astoundingly, a 11 700-kilometre, eight-day flight from the Alaskan breeding grounds back to New Zealand – the longest non-stop migratory flight ever documented. The details are shown on the map. In the course of the year, this bird flew more than 30 000 kilometres. In her life she is likely to make the same flight at least 13 times; this equals the distance of a flight to the moon!
Graphic prepared by Colleen Handel using NASA World Wind
International par tnerships 137
136 Invisible connec tions
In 2008 the USGS repeated their tracking with Bar-tailed Godwits from northwest Australia. This revealed for the first time the route taken by migrating Australian godwits like C3 (photo left with aerial showing) and A9 (below, the bird with numbered black leg flag and aerial). In April these birds flew nonstop to the Yellow Sea, a distance of 6400 kilometres which they completed at speeds averaging 50–55 kilometres/hour. There they joined godwits from New Zealand for a few weeks of refuelling. The Australian godwits then made another non-stop flight, this time to the breeding grounds in northern Siberia – a distance of over 4000 kilometres which they completed in 44–51 hours, averaging 80 kilometres/hour! Breeding in the High Arctic can be a high-risk strategy. Bad weather with unseasonally late snow prevented them from breeding successfully: a 20 000+ kilometre round trip with a negative outcome. After refuelling in the New Siberian islands, the godwits set off on southward migration from mid to late July. Unlike their Alaskan counterparts, which use completely different routes on northward and southward migration, the north-west Australian birds flew back from Siberia to the northern shores of the Yellow Sea, finding and using the same staging sites they had used when migrating north two to three months before. C3 was the first bird to return to north-west Australia, arriving back in Roebuck Bay on 30th August. A9 C3 New Zealand ➔ Alaska
138 Invisible connec tions
The hear t of the Fly way 139
8
The heart of the Flyway Nial Moores & Ju Yong-Ki For the past 10 000 years, since the seas started
through annual dust storms, have created the
somewhat sandy. To the north, however, as the
inactive or buried deep within sediments, and few
mud erupts with a billion holes and miniature
others far north-east to reach Alaska. And yet,
to rise after the last Ice Age, the Yellow and the
huge Yangtze and Yellow River deltas to the west
same body of shallow Yellow Sea water moves
shorebirds or even gulls can tolerate such harsh
volcanoes, burrows of crabs and mud-worms.
despite this abundance and frenetic activity
Yangtze, the Liao and the Amnok, the Han and the
and several large estuaries to the north and east,
with the tides into ever-narrower areas, the tidal
conditions. Southwards, temperatures remain
During this time, the boreal spring, drab-grey
across the wide tidal flats, at low tide there is
Geum rivers have meandered their way, across
at Yalu Jiang, Mundeok, the Han-Imjin, the Geum
range increases (reaching over 9 metres in Korea’s
milder, however, and small numbers of shorebirds
flocks of over-wintering Dunlin and Grey Plover
often little evidence of the birds’ presence beyond
often vast flood-plains, to drain their loads of
and Saemangeum. To the slow rhythm of
Gyeonggi Bay), creating complex landscapes of
and shell-fishers remain active. One species, the
are joined by waves of Bar-tailed Godwits, the
the occasional melancholic cry of a distant
nutrient-rich silt and muddy waters into the shallow
millennia, the natural processes of sea-level
gullied mud and deep creeks. In the higher areas,
boldly patterned Eastern Oystercatcher, even
males now coloured a deep orange and brown,
curlew or plover. But as the hours pass, and the
basin we now call the Yellow Sea. Bordered by
change and sedimentation created over three
almost above the reach of the tide, red and green
reaches its peak in number in the Yellow Sea in
arriving after many thousand kilometres of
shimmering horizon resolves itself more clearly
China to the north and west and the Korean
million hectares of intertidal flats, the largest
carpets of saltmarsh are found.
mid-winter, most birds concentrating at just one
unbroken flight from New Zealand and Australia.
into land, sea and sky, and as the shell-fishers
peninsula to the east, this semi-enclosed sea is
expanse in the world – half of which has
Although it contains some of the most
By May, most shorebird species reach
trudge in weary lines back homeward across the
shallow: 46 metres on average, with northern
subsequently been lost to reclamation in only a
extensive and naturally productive tidal flats and
Each year, slowly in March, and then more
their peak number in the Yellow Sea. Coming
mud, clouds of distant birds can be seen to lift
Bohai Bay averaging a mere 26 metres in depth.
couple of human generations.
sea-shallows in the world, the Yellow Sea at
quickly through April, temperatures rise. It is with
from a broad arc of coastal habitats across
and rise with the incoming tide. Land becomes
estuary, the Geum, in Korea.
Year by year, grain by grain, land has been
Where the Yellow Sea meets with the East
times may appear barren. In the winter months,
this warmth of spring that crabs become active
continents, they are now concentrated and refuel
sea again, and small groups of shorebirds peel
moved seaward into the Yellow Sea. Sediments
China Sea, the daily tidal range is fairly small, and
especially in northern Bohai Bay, tidal flats and
again, scuttling across the tidal flats, while pools
frantically before another long flight, some north-
away from the horizon. Once seen, then invisible
brought by the rivers, and to a lesser extent
many of the sediments and tidal flats are
shallows can freeze. Most tidal flat animals stay
flash silver once more with shallows fish, and the
west to Mongolia, others north to Siberia, still
again, before lifting and rising, moving ever
Shell–fishers and shorebirds: both dependent on tidal flats, and both threatened by reclamation in the Yellow Sea.
• Invisible
无 形的联系
The hear t of the Fly way 141
Photo copyright Choe Jong-In, South Korea
On an icy February day, Dunlin roost on frozen Sihwa Lake, Ansan City, South Korea.
population of 8500), Chinese Egret (3000) and the
the sediment-laden rivers that feed the sea are
wetland habitats and provides guidance and
Black-faced Spoonbill (1500).
now dammed or dyked, and some, like the Yellow
frameworks for their protection. The Flyway
As elsewhere in the world, fisheries have
River, often fail to even reach their estuaries,
Partnership has been launched, aiming, through
declined as a consequence of over-fishing,
allowing the sea to cut away at the land, eroding
the conservation of birds, to achieve social and
pollution and coastal reclamation. Nevertheless,
both tidal flats and human sea-defences.
economic benefits for the communities that share
the Yellow Sea still supports the food needs of
Crowded coastal cities, many of which have
and depend on the very same habitats. The
millions of people as well as millions of birds.
doubled in size in less than a single human
mechanisms are in place to ensure that sites
Fisher-folk, like the shorebirds, follow the daily
lifetime, are at once centres of economic growth
where shorebirds breed, spend the non-breeding
rhythm of the tides, to rake or poke or claw the
and environmental degradation, sprawling across
season and stop to rest and refuel on their long
mud for shells, shrimps and lugworms. Others
former tidal flats, on land made ‘permanent’ by
migrations remain available to future generations.
build piles of rocks (Doksal) to trap fish carried in
seawalls and dykes. Half of the intertidal areas of
Now, in all parts of the Flyway – from
by the tide that are then left stranded as the tide
the Yellow Sea have been lost. Many remaining
Alaska and Siberia in the north, throughout
falls. Some bury pipes and buckets to funnel
areas are threatened.
eastern Asia, and southward through Australasia
unwary crabs, or erect rows of poles and nets, bare
Migrant shorebirds, specialist waterbirds
– all of us need to take the action necessary to
forests in a treeless landscape, for cultivating
and local fishing communities now all face the
ensure that sufficient sites are protected and the
closer, joined this time by a thousand more:
estuaries, to be replaced in turn by smaller flocks
seaweeds. Large fleets of fishing boats sweep for
same predicament. The loss of more tidal flats
resources provided to guarantee their long-term
undulating, twisting, shimmering waves of birds
of tundra-born Dunlin, and a few thousand
shrimp in estuaries and at sea. Traditional cultures
will mean the loss of more life. Extinction, both of
conservation. Like the shorebirds that rise into
and light, and a chorus of sound, diverse and
Eastern Oystercatchers, heavy-built and strong
around the Yellow Sea celebrate good harvests
a way of life and of once abundant species, is a
the air to cross continents and oceans, so too
rich with excitement – this is one of our planet’s
enough to survive the winter.
and safe homecoming. They value the human
real possibility.
must we all rise to the challenge – to secure a
However close to the brink, signs are
Throwaway society: the Yellow Sea region has one of the highest human population densities in the world and new models of sustainable development, with resource and biodiversity conservation at the core, are urgently needed.
The Yellow Sea’s tidal flats and coastal
connections to the sea by eating, salt-pickling,
These shorebirds seem so numerous on
wetlands support more than 30% of the Flyway
exporting and exhorting the riches provided by
emerging
the tidal flats that remain available to them
population of 25 shorebird species during
Yongwang, the Korean Neptune of the sea. But as
unsustainable development just might be starting
because they have nowhere else to go. Their life,
northward migration. For 15 species, including
reclamation overwhelms once great estuaries, both
to recede. An increasing number of local
as always, depends on the food resources of the
the Bar-tailed Godwit, the Yellow Sea supports
the sea and the fishers retreat. With the
communities and governments are uniting to
For the most recent information about shorebirds on this Flyway and actions you can take to
Yellow Sea. It is estimated that some two million
almost the whole Flyway population at this time;
Saemangeum reclamation alone, 20 000 people
protect the riches of the Yellow Sea through local
get involved, visit these websites:
shorebirds pass through the Yellow Sea during
and for others, it supports almost the whole world
have lost their livelihoods and their habitat. Life-
decisions, national wetland conservation laws
Australasian Wader Studies Group: www.awsg.org.au
northward migration in April and May each year.
population. The Yellow Sea is the single most
giving mudflats and shallows are becoming deserts,
and international conventions such as Ramsar.
Broome Bird Observatory: www.broomebirdobservatory.com
This is 30%, or even 40%, of all of the shorebirds
important region in the world during migration for
with plans to turn the wetlands into ecologically
Voices in accord with that of the Chinese
Global Flyway Network: www.globalflywaynetwork.com.au
of the vast East Asian – Australasian Flyway. It is
the Great Knot, and also for the critically
barren golf courses and industrial estates.
environmental protection official who asked,
Australian Government: www.environment.gov.au/biodiversity/migratory/waterbirds
a huge number, even though far less than the
endangered Spoon-billed Sandpiper and the
The Yellow Sea is undoubtedly under
‘What is the use of getting rich if the beauty of
Miranda Shorebird Centre: www.miranda-shorebird.org.nz
human population of just a single city like Seoul
endangered Nordmann’s Greenshank. The latter
enormous pressure. Over 10% of the world’s
the birds is lost?’ are getting louder.
Wetlands International China Office: www.wetwonder.org
or Shanghai. On southward migration too,
two are among the world’s rarest shorebird
human population live within the catchment area
For shorebirds to continue to make these
between July and October, when temperatures
species. It also forms the heart of the range of the
of its rivers, demanding its freshwater resources,
amazing journeys, to weave these invisible
Birds Korea: www.birdskorea.org
fall as dry, cold monsoon winds start to blow
Eastern Oystercatcher. Three more breeding
using rivers for garbage and sewage disposal,
connections between land, sea and sky into the
US Fish and Wildlife Service: www.fws.gov/migratorybirds/shrbird/shrbird.html
across the region, another million or more
waterbird species on the brink of extinction are
and working in agriculture or industries producing
future, even more action is needed. The Ramsar
USGS Alaska Science Center: http://alaska.usgs.gov/science/biology/shorebirds/barg.html
shorebirds stage in the Yellow Sea. Then they
also largely dependent on the shoreline resources
consumer goods to meet insatiable global
Convention
PRBO Conservation Science: www.prbo.org/cms
too fan out towards more southern beaches and
of the Yellow Sea: Saunders’s Gull (with a world
demands that pollute the air and water. Most of
responsibility of governments to protect important
greatest wildlife spectacles.
that
this
makes
destructive
clear
the
tide
of
international
future for the birds, the tidal flats and the living world which we all share.
Wetlands International: www.wetlands.org/
142 Invisible connec tions
The hear t of the Fly way 143 Bordered by China and the Korean Peninsula, the Yellow Sea is the heart of the East Asian – Australasian Flyway and supports huge concentrations of migratory shorebirds such as these Great Knots (left) on both northward and southward migration. The satellite image of the Yellow Sea (right) shows the vast extent of the tidal flats and estuaries formed by the great rivers of Asia. However, seen closer-up, from an aeroplane or through the eyes of a migrant shorebird for example, much of this coastline has already been squared-off into fishponds or straightened with seawalls, and the rivers dammed by barrages, leaving ever-diminishing areas of tidal flats for shorebirds.
MODIS Terra image, acquired on 14 March 2008. Image processing courtesy of David Douglas, USGS Alaska Science Center
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Healthy Wetlands, Healthy People, Healthy Shorebirds! People and birds alike depend on the life-giving abundance and ecological health of the Yellow Sea’s tidal flats and sea-shallows. In May, up to two million shorebirds stage in the Sea: nearly 40% of all the long-range migrant shorebirds of the Flyway.
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The Yellow Sea is of vital importance to local communities, to regional fisheries and to global biodiversity. Several waterbirds of special conservation concern, including the vulnerable Saunders’s Gull (facing page, upper left), the endangered Black-faced Spoonbill (facing page, upper right), the Far Eastern Oystercatcher (below left) and the critically endangered Spoon-billed Sandpiper (below right), depend on the Yellow Sea.
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The Yellow Sea region, with 10% of the world’s human population, is under increasing pressure. Most of the rivers are dammed or dyked. Huge coastal cities are rising as centres both of economic growth and environmental degradation. Many tidal areas are being transformed into new ports, industrial estates and oilfields, all intersected by bridges and roads, at a terrifying pace.
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Reclamation has already destroyed almost half of the Yellow Sea’s tidal flats. Until completion of a 33-kilometre seawall in 2006, Saemangeum in South Korea was the Yellow Sea’s most important shorebird site. An indication of its former richness could be seen on the tidal flats shortly after the seawall was closed, when countless thousands of large shellfish rose to the mud surface as they died (left). Without restoration of tidal flow, the whole ecosystem will continue to degrade, wrecking fisheries and causing declines in species like the Great Knot (lower right).
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Increased awareness of the national and international importance of Yellow Sea tidal flats has led to the recent cancellation of the reclamation planned for the Geum Estuary in South Korea (above) and improved protection of Yalu Jiang National Nature Reserve in China (right), now the Yellow Sea’s most important remaining shorebird site. But few measures have been taken to prevent over-harvesting or pollution of the tidal flats upon which shorebirds depend.
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In line with national laws and the Ramsar Convention, an increasing number of other internationally important coastal wetlands are also winning protection, such as Suncheon Bay in South Korea (left) and Chongming Dongtan in China. Environmental education at these sites helps local communities understand the important connections between their wetlands, their future and the future of shorebirds.
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The Yellow Sea has long given life to people and to the shorebirds of the East Asian – Australasian Flyway. For the Yellow Sea to remain healthy and productive, and for these amazing birds to continue weaving invisible connections through the skies and the hearts of people, much more conservation action is needed. The time to act is now!
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Acknowledgements The connections that shorebirds make between countries and habitats are mirrored by the links made between people fascinated by shorebird ecology. The photographs in this book which illuminate these connections could not have been taken without the opportunity to share experiences, and gain the invaluable advice and practical support of dedicated volunteer and professional shorebird researchers from the length of the Flyway: In Australia: The past and present staff and committee of Broome Bird Observatory, Australasian Wader Studies Group, Adrian Boyle, Alison Russell-French, Andrea Spencer, Chris Hassell, Clive Minton, Danny Rogers, Grant Pearson, Helen Macarthur, Iain and Sandy Stewart, Jan Lewis, John Curran, John, David and Helen Stoate, Ken and Carlene Gosbell, Mark Barter, Maurice O’Connor, Mavis Russell, Petra de Goeij and Theunis Piersma. In New Zealand: Staff and committee of Miranda Naturalist’s Trust, Adrian and Janice Riegen, Brett Gartrell, David and Vicky Melville, Gillian Vaughan, Keith Woodley, Phil Battley, Rob and Anneke Schuckard and Tony Habraken. In China: Yan Meifang and staff of Yalu Jiang National Nature Reserve, Ma Qiang and the banding team at Chongming Dongtan Nature Reserve, Professor Chen Kelin, Chen Li, Jia Na, Yan Hong Yan (Nick), Professor Zhijun Ma. In Korea: Staff and members of Birds Korea, Dr Kim Seok Yee and staff of the Mokpo Natural History Museum, Andreas Kim, Choe Jong-In, Jeon Shi-Jin, Ju Yong-Ki, Kim Beom-Su, Kim Hyang-Ee, Kim Sona, Lee Chang Gu, Nial Moores, Park Meena, Robert Newlin and Shim Kyu-Sik. In Russia: Dr Elena Lappo, Dr Evgeny Syroechkovskiy, Fyodor Kondrashov, James Gilroy, Jens Gregersen, Ludmila Meleschenko, Maxim, Dr Pavel Tomkovich and Vladimir Arkhipov. In Alaska: United States Geological Survey Alaska Science Center, Yukon Delta National Wildlife Refuge, Bob Gill, Brian McCaffery, Colleen Handel, Dan Mulcahy, Daniel Ruthrauff, David C. Douglas, Eddie Corp, Lee Tibbitts, Andrea Pommeroy, Sarah Lovibond and Nils Warnock.
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Thank you
This picture of a Bar-tailed Godwit on his nest is literally the last image I took for this book. While sitting near the bird for hours in the tundra in Alaska, I contemplated the long travels I had made along this spectacular flyway from New Zealand to the Arctic. This splendid bird, a 300-gram bundle of avian energy, had travelled the same distances completely by his own power. I could only do all that travelling, visit all the marvellous shorebird places and take pictures of these fascinating birds thanks to the kind assistance of many people, organisations and institutes in New Zealand, Australia, China, South Korea, the Russian Federation (Siberia) and USA (Alaska). I thank you all for your incredible help and friendship, and your contribution to this book. I hope it makes many more people aware of the invisible and very vulnerable connections shorebirds depend upon. Jan van de Kam