invisible connections

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

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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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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

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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


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



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


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



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



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


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.


20



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


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



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


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!


28


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



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



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



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


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



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


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.


44


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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



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


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.


92



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


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


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


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.


100



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


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



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



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


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.


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.



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.



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).


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.



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.



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.


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



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


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.



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.



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.



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



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


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


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/


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



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.



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.



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.



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).



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.



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.


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!




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.


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