weedy shrub lantana Lantana camara; and. 5. whether there were any movements of mammals along the stream vegetation. ICSIRO Division of Wildlife and ...
The utility to birds and mammals of remnant riparian vegetation and associated windbreaks in the tropical Queensland uplands FRANCIS CROME,] JODI ISAACS 2 and LES MOORE] Birds and mammals were censused in a ribbon of remnant vegetation along a stream connecting two rainforest fragments on a farm on the Atherton Tablelands of North Queensland. The vegetation consisted of two larger (6.5 and 19.6 hal and one smaller forest remnant (1.1 hal and numerous tiny disconnected patches scattered across the property and along the creek. These were classified into five types - "Forest", "Regeneration", "Copse", "Lantana" and "Tobacco Bush". Censuses were also done in four windbreak plantings. Sixty-four specie" of birds were recorded in systematic censuses in the patches along the creek and in the windbreaks. Along the creek, "Forest" patches had the most species and the most rainforest species followed by "Copse" and "Regeneration" sites. "Lantana" patches were surprisingly rich in species; a total of 32 were recorded including nine rainforest species. The fewest bird species were recorded in the windbreaks which were particularly poor in rainforest species. Small mammals were live trapped in the three larger patches, in the ribbon and in one windbreak. Eleven species were captured - six rainforest, three grassland and two introduced. The grassland species were not caught in the larger forest patches and two rainforest rodents were not caught along the creek. Nothing was caught in the windbreak but grassland species were caught in an adjoining abandoned orchard. Three species of arboreal mammals were recorded by spotlighting - Lumholtz' Tree-kangaroo Dendrolagus lumholtzi, Coppery Brushtail Possum Trichosurus vulpecula johnstonii and Green Ringtail Possum Pseudocheirus archeri. All occurred in the stream vegetation as well as the larger forest patches. None were seen in any of the four windbreaks. It is concluded that the creek vegetation is valuable wildlife habitat. The windbreaks were less so but were still useful to the fauna on the study area. Keywords: Rainforest, Riparian Corridor, Landscape, Fragments, Birds, Mammals, Restoration, Habitat, Matrix.
INTRODUCTION THE forests of the Wet Tropics of north Queensland, like many tropical areas, have been fragmented. The landscape now consists of larger tracts of forest on the surrounding massifs with remnant forest patches and variously vegetated streams in the farmland that occupies the flat and rolling plains and tablelands. The need for ecological restoration of these landscapes has been recognized and several multi-purpose tree-planting schemes are underway in the Wet Tropics. These schemes, like most restoration schemes, frequently include wildlife conservation as one of the benefits they provide and, in this context, usually promote their value as wildlife corridors. This is particularly the case in programmes for revegetating stream banks, even though the primary aim may be soil stabilization or water quality improvement. The Atherton Tableland is the focus for several tree-planting and landscape restoration schemes, as well as studies of the effects of forest fragmentation on birds (Warburton 1987) and mammals (Laurance 1990, 1991, in press; Crome, unpub!. data) in forest fragments and ribbons. Obviously, ribbons of remnant or planted vegetation have a potential to enhance wildlife conservation within fragmented landscapes. They can provide habitat in their own right and, theoretically, by acting as corridors, i.e., facilitating
animal movements, they can promote regional survival of species (Gotelli 1991; Pulliam and Danielson 1991). Acceptance of the role of vegetation ribbons as corridors has been perhaps overenthusiastic. There are data to demonstrate that ribbons are visited by wildlife (e.g., Bennett 1988, 1990 a and b; Arnold et al. 1991; Date et al. 1991; Prevett 1991; Saunders and de Rebeira 1991), but few to determine whether they really act as corridors (Simberloff et al. 1992), a difficult and perhaps impossible task in many cases (Crome 1994; Inglis and Underwood 1992; Nicholls and Margules 1991). We present here the results of a short study on the Atherton Tableland that examined what wildlife used five small ribbons of vegetation one ribbon of remnant vegetation along a stream and four windbreaks planted nearby, the two types of vegetation that are most likely to be considered corridors for wildlife. Our aims were to determine: 1. what species of birds and mammals visited the stream vegetation; 2. what species visited four planted windbreaks nearby; 3. how species responded to the type of vegetation along the stream; 4. whether wildlife used the widespread, noxious weedy shrub lantana Lantana camara; and 5. whether there were any movements of mammals along the stream vegetation.
ICSIRO Division of Wildlife and Ecology. Tropical Forest Research Centre, P.O. Box 780 Atherton, Queensland, Australia 4883. Present address: P.O. Box 447, Atherton, Queensland. Australia 4R83. 2Zoo1ogy Department, James Cook University, Townsville, Queensland, Australia 4770. PACIFIC CONSERVATION BIOLOGY Vol. I: 328-43. Surrey Beatty & Sons. Sydney. 1994.
329
CROME, ISAACS and MOORE: WILDLIFE IN RIBBONS OF VEGETATION
In the following discussion "ribbon" means a thin line of vegetation with no implications of its utility and "corridor" means a ribbon which animals use for movement between vegetation fragments. Study area The Atherton Tableland is centred on the township of Malanda (Fig. 1). It was originally vegetated with a range of rainforest and eucalypt formations but most has been cleared for agriculture. The main rural industries are cropping (potatoes, peanuts, maize and tropical fruit) in the drier northern section and dairying, grazing and tea production in the wetter southern region. The mean annual rainfall for Malanda is 1 685 mm concentrated in the December to March period. The study took place within 160 ha of two grazing properties 3 km south of Malanda. The terrain is gently rolling, the soils are red basalts and the original vegetation was upland rainforest ("Complex Notophyll Vine Forest", Tracey 1982). The remaining native vegetation consists of three remnant blocks of forest, termed "William's" (6.5 ha), "Pelling's" (19.6 ha) and "Site 46" (1.1 ha) and numerous tiny remnants and regrowth patches scattered across the property. They form
a discontinuous ribbon along William's Creek which runs from the eastern edge of "Pelling's" to "Site 46" and then north-east to flow into the Johnstone River (Fig. 1). The property was used to produce avocados from two now-abandoned orchards and there were approximately 40 head of beef cattle on the property at the time of the study. The grasslands mostly consist of the introduced Brachiara decumbens and were grazed to between 2 and 14 em high. Tree plantings The owners have planted four windbreaks on the property. Windbreak A was planted in 1972, is 110 m long and consists of two lines, 5 m apart, of Queensland maples Flindersia brayleana, a local rainforest species, spaced at 0.5-5 m. There are approximately 52 surviving trees 8 to 15 m high. Their canopies touch and there is a short grass understorey. Windbreak B, 140 m long, was planted in 1972 and is a mixed ornamental planting that borders the house garden and the western avocado orchard. To the east it consists of a single line of Banksia sp. approximately 4 m apart and 3 m high, and to the west, 7 m away, two lines, 5 m apart, of 12 Eucalyptus grandis and 42 Pinus carribea, ranging
Malanda "x
StudY~
'.
Key to Vegetation Categories mIl • 0-
• -
ill -
m-
COPSE FOREST LANTANA ~ND BREAKS REGENERATION TOBACCO BUSH
Kennedy Highway
N "-----
-----I
1-1
200m
Fig. 1. Map of the study area and its location (inset). P = "Pelling's"; W = "William's"; 46 = "Site 46"; A, B, C and D are the windbreaks. The thin lines are fences and the structures near Windbreak B are farm houses. The grids used for trapping small mammals are outlined and numbered 1 to 8.
PACIFIC CONSERVTION BIOLOGY
330
from 2 to 25 m high. The westernmost line is festooned with introduced and native orchids and the canopies are touching. Between the banksias and the westernmost trees are scattered shrubs and citrus trees. None of the tree species are native to the area although E. grandis occurs in somewhat drier areas a few kilometres to the west. Windbreak C, 290 m long, was planted in 1977 and forms the southern border of the eastern avocado orchard. It is a single discontinuous line of 78 Eucalyptus torreliana, a species found in drier rainforest formation within the wet tropics, and E. citriodora 2 to 20 m high and approximately 8 m apart. There are clumps of regenerating rainforest trees (up to 8 m high) between the eucalypts forming a discontinuous, dense but very narrow (0.5-2 m wide) understorey. The canopies of the remaining trees do not touch. Windbreak D, 110 m long, also planted in 1977, forms the eastern border of the eastern orchard. It now consists of a single line of 27 scattered trees of Pinus carribea and E. torreliana up to 8 m tall, with a grassy understorey. A single P. carribea has reached 15 m in height. The canopies of these trees do not touch. METHODS Vegetation Low level aerial photographs were taken of the study area and a map produced showing each identifiable patch of vegetation. Each of these 53 patches was classified into one of five categories. A "Forest" patch retained some mature rainforest characteristics - there were still several larger trees and the floor was still open and shaded. A "Copse" patch had only one or two larger forest trees remaining with an abundance of regrowth saplings forming a dense layer. A "Regeneration" patch consisted of short regrowth trees, possibly with a dead or dying stag; lantana was usually present but did not dominate the patch. A "Lantana" patch consisted of lantana, with or without a few regrowth saplings and/or a single tree at the centre. A "Tobacco Bush" patch consisted entirely of the weedy treelet Tobacco Bush Solanum mauritianum. Species lists of the woody plants over 1 m high were made for 46 of these patches along and within the vicinity of William's Creek. The larger remnant blocks were not surveyed botanically. Birds Birds were censused in the vegetation patches along William's Creek and the windbreaks from 1-27 July, 1992 and again from 1-30 November, 1992. The data from both periods were combined. Figure 2a shows the locations and identity numbers of the censused patches. The larger
remnant blocks were not censused but complete species lists were already available for them from previous studies (Warburton 1987 and unpubl. obs. during 1991 and 1992 of F. H. J. Crome and L. A. Moore).
Creek censuses Each patch was censused by the same single observer on 19 occasions. The duration of a single census at a particular patch was fixed according to its area and varied from 4 to 10 minutes. During this period all birds seen and heard were recorded. Only birds within the patch of vegetation or in the creek itself were included; birds in the grassland or flying overhead were not. On one day the patches along one bank were censused sequentially and the next day those on the other bank were censused, since the observer had to be on the same side of the creek as the censused patch. A sequence of censuses along one bank took 3 hours and started at dawn. Windbreak censuses The time spent censusing windbreaks depended upon their length. A census of the three long windbreaks took 20 minutes and the short windbreaks 10 minutes. Species accumulation curves were drawn for each and censuses terminated when the curves flattened out and there had been no species added for that windbreak in three consecutive censuses. Thus Windbreak A was censused 20 times, B 16 times and C and D 13 times each. They were sampled at most times of the day but primarily in the morning. Species classification Bird species were classified into one of six categories according to habitat preference and dependence on rainforest vegetation using Crome (1990) and the natural history knowledge ofF. H. J. Crome and L. A. Moore. Rainforest Type 1 Species (RFl) are totally dependent upon rainforest. They are seen in other habitats but could not survive without rainforest nearby. Rainforest Type 2 Species (RF2) are rainforest species but with a wider habitat tolerance than Type 1. They are commonly seen in other habitats and sometimes far from rainforest but it is unlikely they would survive in any number in a landscape with no rainforest. Mixed Habitat Species (MH) occur in a range of forested habitats from rainforest to eucalypt woodlands. Open Forest Species (OF) are birds of eucalypt forests, woodlands and savannahs, that rarely enter rainforest. Grassland and Wetland Species (GR) occupy open grasslands, freshwater streams and swamps. Raptors (R) are birds of prey. Analysis The frequency of occurrence of each species at each censused patch was calculated as the number of censuses on which the species was recorded at
CROME, ISAACS and MOORE: WILDLIFE IN RIBBONS OF VEGETATION
331
RFl Species -
7108
I! -
•
5 to 6
OF Species
0- 1 UJ - 2
UD-3104
0-
1102
III -
3
•
4
-
(}
GR Species • IlII -
7 to 8 5106
lID -
3104
0-
1102
(}
Total Species MH Species • III -
au -
0-
•
10 to 13 710 9 410 6 110
-
l1li UU-
0-
3
301039 21 1029 121020 11011
(}
(}
Fig. 2 (a-f). The distribution of numbers of bird species of each category along William's Creek. The identity numbers of the
patches at which birds were censused along William's Creek are given on Figure 2a. Sites 4, 12,20,36,39 and 43 were not used for bird censuses and are not labelled.
that site divided by the total number of censuses. The number of species of each group occurring at the site was the number of species recorded over the entire set of censuses. Formal statistical testing of relationships between bird occurrence and ecological variables such as patch type and area, inter-patch distance and distance from the larger remnant blocks are not presented because of the obvious lack of independence between the patches. The distances between patches are very small in relation to the movements that birds are capable of and we preferred not to misuse formal testing by applying it in such a situation. Pattern analysis, however, is more robust to lack of independence (L. Belbin, M. Thomas, pers. comm.) and was used to examine
the similarity of sites in terms of bird composition. We therefore derived a set of groups to examine relationships amongst sites by hierarchial agglomerative cluster analysis in the form of Flexible Unweighted Pair Group Mean Analysis (UPGMA: Belbin et al. 1992) using the PATN package (Bel bin 1992). The data used were the frequencies of each species at a site. This procedure groups sites successively according to their similarities. Small mammals Small mammals were monitored using live trapping on eight trapping grids. Grids 1--6 were along William's Creek, Grid 7 along Windbreak A and around the house and Grid 8 in the western
332
PACIFIC CONSERVATION BIOLOGY
orchard and along part of Windbreak B (Fig. 1). All grids were trapped simultaneously from 14-22 November, 1991; and again from 12-20 March, 1992. Each grid was trapped continuously over each nine day sampling period using Elliot traps and larger wire cage traps baited with rolled oats soaked in vanilla essence. The exact trap number and disposition at each grid varied depending upon terrain, the habitat and the size of the area being trapped. Grid 1 (rainforest) consisted of three lines of six traps on each side of William's Creek within the "Pelling's" remnant block (30 Elliot traps and six cage traps). The lines and traps were at 15 m intervals. Grid 2 (rainforest and weedy pasture) consisted of three lines on each side of William's Creek but only 22 traps were used (16 Elliot traps and six cage traps), 11 in rainforest and 11 in open pasture. The mixture of grass and herbs in the open pasture differed greatly between trapping periods, ranging from basically bare ground in November to patchy thickets of introduced weeds with odd clear areas of shorter pasture grass during March. Grid 3 (complex of pasture, sedge and regrowth) used the same trapping pattern and trap numbers as at Grid 1 with three lines of traps on either side of the stream. It sampled patches 10, 13, 15, 16 and 17, the sedge beds in the creek and open pasture. Grid 4 (copse, lantana, and pasture) sampled patches 25, 27 and 28, the sedge beds in the creek and open pasture. It also was trapped using the same trapping pattern as Grid 1. Grid 5 (copse, lantana, and pasture) sampled patches 37, 38, 40 and 41, the sedge beds in the creek and open pasture. The number and arrangement of traps was the same as for Grid 1. Grid 6 ("Site 46") consisted of two parallel lines of traps 5 m apart and the traps set at 2 m intervals. Each line had two cage traps and eight Elliot traps making 20 traps in all. Grid 7 (Windbreak A, house area and garden) consisted of 25 Elliot traps and two cage traps placed in a line along the windbreak and randomly around the house. Grid 8 (western avocado orchard) totalled 10 cage traps and 39 Elliot traps in four lines. Data on small mammals from the larger remnant blocks "Pelling's" and "William's" were available from another long-term trapping study in these blocks. Data collected in December 1991 and March 1992 during that study were used for comparison with the data from William's Creek. Trapping in these blocks was done on eight small grids distributed through the forest, each grid consisting of two parallel lines of traps 5 m apart
and the traps set at 2 m intervals. Each line was of two cage traps and eight Elliot traps making 20 traps in all. The eight grids were trapped simultaneously for three nights. Arboreal mammals The study area was spotlighted on three nights in October and three nights in November 1992, either side of the new moon. Each night two observers walked circuits lasting four hours from 19:30 to 23:30 hrs around all vegetation patches, the larger remnant blocks and the windbreaks. The positions of all mammals observed were plotted on field maps. RESULTS Vegetation The distribution of the five types of patches in the entire study area is shown in Figure 1. Overall there were 22 small "Forest" patches totalling 3.2 ha, seven "Copse" patches totalling 0.9 ha, 19 "Regeneration" patches totalling 0.6 ha, 11 "Lantana" patches totalling 1.7 ha and one "Tobacco Bush" patch of 1.2 ha. About one-third of the total vegetation (including "Site 46" but excluding "Pelling's" and "William's") occurred as a discontinuous ribbon within 30 m either side of the centre of William's Creek. Patch 10 was very different to the other "Forest" patches because it was used as a camp by the cattle on the property, and the ground underneath was bare as a result. The numbers of species in each surveyed patch is given in the Appendix. Sixty-eight species in all were recorded including 11 weedy or introduced trees and shrubs. The bulk of the tree and shrub species (species lists available from F. Crome) are common in early successional forests, although some are larger remnant trees of species more common in later successional and mature forests e.g., Dysoxylum rufum and Doryphora aromatica. The introduced weed tree Camphor Laurel Cinnamomum camphori was found in nine sites along the creek. The patches in William's Creek and the larger vegetation remnants (excluding "Pelling's", "William's" and "Site 46") contained 61 species of native rainforest trees. Birds
The creek and the larger remnant blocks The results of the censuses are given in Tables 1 and 2 and the Appendix. The bird data are presented as presence/absence. Frequency data for individual sites are available on request. Between half and two-thirds of the rainforest and open forest species that were recorded in the larger remnant blocks of "Pelling's" and "William's", occurred in the creek remnants.
333
CROME, ISAACS and MOORE: WILDLIFE IN RIBBONS OF VEGETATION
Table 1. Birds seen on censuses along William's Creek and known to be in the major forest blocks. X = species recorded as present. Common Name
Scientific Name
P*
W
Megapodius reinwardt Ptilinopus superbus Ptilinopus magniftcus Lopholaimus antarcticus Cyclopsitta diophthalma Coracina lineata Tregellasia capito Poecilodryas albispecularis Colluricincla boweri Machaerirhynchus flaviventer Sericornis keri Acanthiza katherina Xanthotis macleayana Scenopoeetes dentirostris Ailuroedus melanotis Ptiloris victoriae
X X X X X X X X X X X X X X X X
X X X X
Alectura lathami Macropygia amboinensis Columba leucomela Chalcophaps indica Monarcha trivirgatus Monarcha melanopsis Psophodes olivaceus Sericornis magnirostris Sericornis citreogularis Gerygone mouki Cormobates leucophaea Lichenostomus frenatus Sphecotheres viridis Cracticus quoyi
X X X X X X X X X X X X X X
Cacatua galerita Trichoglossus haematodus Trichoglossus chlorolepidotus Alisterus scapularis Platycercus elegans Cuculus flabelliformis Chrysococcyx basalis Chrysococcyx lucidus Chrysococcyx minutillus Chrysococcyx russatus Eudynamys scolopacea Alcedo azurea Dacelo novaeguineae Halcyon sancta Eurystomus orientalis Lalage leucomela Colluricincla megarhyncha Pachycephala pectoralis Myiagra rubecula Rhipidura ruftfrons Rhipidura fuliginosa Rhipidura leucophrys Sericornis frontalis Philemon buceroides Philemon corniculatus Philemon citreogularis Meliphaga lewinii Acanthorhynchus tenuirostris Myzomela obscura Myzomela sanguinolenta Dicaeum hirundinaceum Zosterops lateralis o riolus sagittatus Dicrurus bracteatus Strepera graculina
X X X X X X X X
46
C
WB
Rainforest Type 1 Grange-footed Scrubfowl Superb Fruit-Dove Wompoo Fruit-Dove Topknot Pigeon Double-eyed Fig-Parrot Yellow-eyed Cuckoo-shrike Pale-yellow Robin Grey-headed Robin Bower's Shrike-thrush Yellow-breasted Boatbill Atherton Scrubwren Mountain Thornbill Macleay's Honeyeater Tooth-billed Bowerbird Spotted Catbird Victoria's Riflebird
X X
X X X X Xl X X Xl X X
X X
X X
X X
X X X
X X
X X
X X
X X
X X X
X X X
X X
X X X X
X
Rainforest Type 2 Australian Brush Turkey Brown Cuckoo-Dove White-headed Pigeon Emerald Ground-Dove Spectacled Monarch Black-faced Monarch Eastern Whipbird Large-billed Scrubwren Yellow-throated Scrubwren Brown Warbler White-throated Treecreeper Bridled Honeyeater Figbird Black Butcherbird
X X X X X X X Xl X X X X
X
X
X X X
X
Mixed Habitat Species Sulphur-crested Cockatoo Rainbow Lorikeet Scaly-breasted Lorikeet Australian King Parrot Crimson Rosella Fan-tailed Cuckoo Horsfield's Bronze-Cuckoo Shining Bronze-Cuckoo Little Bronze-Cuckoo Gould's Bronze-Cuckoo Common Koel Azure Kingfisher Laughing Kookaburra Sacred Kingfisher Dollarbird Varied Triller Little Shrike-thrush Golden Whistler Leaden Flycatcher Rufous Fantail Grey Fantail Willie Wagtail White-browed Scrubwren Helmeted Friarbird Noisy Friarbird Little Friarbird Lewin's Honeyeater Eastern Spinebill Dusky Honeyeater Scarlet Honeyeater Mistletoebird Silvereye Olive-backed Oriole Spangled Drongo Pied Currawong
X X X X X X X X X X X X X X X X X X X X X X X
X X X X X X X
X X
X
X 1.2 X X
X
X
X X
X X
X X
X X
X
X X X
X X X
X X X X X X
X
X X X
X X X X X X X X X X
X X X X X X
X
X X
X X
X X
X X
X X X X X
X X X X X X X X X X X X
X X X X
PACIFIC CONSERVATION BIOLOGY
334
Table 1 - continued Common Name
Scientific Name
P*
Geopelia placida Geopelia humeralis Cuculus variolosus Scythrops novaehollandiae Halcyon macleayii Coracina novaehollandiae Coracina papuensis Coracina tenuirostris Lalage tricolor Cracticus nigrogularis
X X
W
46
C
WB
X
X
X
X X
X
X X
Open Forest Species Peaceful Dove Bar-shouldered Dove Brush Cuckoo Channel-billed Cuckoo Forest Kingfisher Black-faced Cuckoo-shrike White-bellied Cuckoo-shrike Cicadabird White-winged Triller Pied Butcherbird
X X X X X
X
X X X X
X X
Open Grassland/Wetland Species
Ardea novaehollandiae Threskiornis aethiopica Anas superciliosa Coturnix australis Gallirallus philippensis Amaurornis olivaceus Centropus phasianinus Megalurus timoriensis Cisticola exilis Malurus melanocephalus Neochmia temporalis Lonchura castaneothorax Acridotheres tristis Grallina cyanoleuca Gymnorhina tibicen
White-faced Heron Sacred Ibis Pacific Black Duck Brown Quail Buff-banded Rail Bush-hen Pheasant Coucal Tawny Grassbird Golden-headed Cisticola Red-backed Fairy-wren Red-browed Firetail Chestnut-breasted Mannikin Common Myna Australian Magpie-lark Australian Magpie
X X X X X X X
X X
X X
X X X X X X X X
X
X X X X X
Raptors
Milvus sphenurus Accipiter fasciatus Accipiter cirrhocephalus Accipiter novaehollandiae Ninox novaeseelandiae Tyto alba
Whistling Kite Brown Goshawk Collared Sparrowhawk Grey Goshawk Southern Boobook Barn Owl
X X X X X
X X
*P = Pelling's Forest Block, W = William's Forest Block, 46 = Site 46, C = Creek, WB = Windbreaks. IData from Warburton (1987); not recorded by present observers. 2Could be C. russatus?
Table 2. Number of species of different bird groups in censuses in the various vegetation types along William's Creek. Entries are the number of species recorded over the n sites of a vegetation type after 19 censuses. The number in brackets is the proportion that the group makes up of the total species for that vegetation type.
Patch
n
"Forest" "Copse" "Regeneration" "Lantana"
11 4 16 8
RFI 9 4 4 3
(19%) (11%) (11%) (9%)
Bird Group MH
RF2 9 7 7 6
(19%) (19%) (18%) (19%)
20 18 IS 14
(42%) (50%) (39%) (44%)
OF 4 2 3 2
(8%) (6%) (8%) (6%)
GR 5 5 9 7
(10%) (14%) (24%) (22%)
R
Total
1 (2%) 0 0 0
48 36 38 32
3 (4%) 1 (2%) 0
74 60 32
Larger Forest Blocks Pelling's Block William's Block Site 46
16 (22%) 14 (23%) 6 (19%)
14 (19%) 12 (20%) 8 (25%)
31 (42%) 29 (48%) 14 (44%)
Fifty-six per cent of the Rainforest Type I (RF1) and 64 per cent of both the Rainforest Type II (RF2) and Mixed Habitat (MH) species found in the larger remnant blocks occurred in the creek sites (Table 1). Similar numbers of Open Forest species (OF) species were found in the creek as in the larger remnant blocks but only two of the nine species were common to both. Far more
6 (8%) 2 (3%) 3 (3%)
4 (5%) 2 (3%) 1 (1%)
GrasslandlWetland (GR) species were found the creek sites.
III
There were also changes in the relative proportions of the various bird groups in the different patch types (Table 2). The "Forest" patches had a very similar assemblage to the larger remnant blocks. The composition of the assemblages in "Copse"
335
CROME. ISAACS and MOORE: WILDLIFE IN RIBBONS OF VEGETATION
and "Regeneration" patches, however, were quite dissimilar to those in the larger remnant blocks and "Forest" sites. Although the proportion of RF2 species was similar there was only 11 per cent of RFI species in "Copse" and "Regeneration" patches, compared to 19-23 per cent in the larger remnant blocks and "Forest" sites. Moreover the proportion of GR species increased to 24 per cent for the "Regeneration sites". "Copse" patches had a greater proportion of MH species than "Regeneration" patches. "Lantana" patches had only a few species less than "Copse" and "Regeneration" patches and had the lowest proportion of RFI species. The trends shown in Table 2 indicate a major reduction in the absolute numbers of RFI species from the "Forest" patches to the other three types although the proportional reduction was smaller. RF2 species showed a similar but smaller absolute decrease but their proportional representation in the assemblages remained stable. There was a gradual decline in MH species from "Forest" to "Lantana" patches and a major increase in GR species from "Forest" and "Copse" to "Regeneration" and "Lantana" patches. These changing proportions indicate that the bulk of the absolute species reductions going from "Forest" patches to the other patch types is of RFI species and that going from "Copse" to "Regeneration" and "Lantana" involves a loss of MH species and a gain of GR ones. The larger remnant that is "Site 46" has a composition similar to the "Forest" patches. The GR species in the creek sites were mostly on the edges of the patches. The interiors of the larger remnant blocks were searched in preference to the edges so the few GR species recorded are likely to be an underestimate. There were few species of raptors and they tended to be seen sitting in the taller trees anywhere on the properties, except for the two Accipiter species which were not recorded outside the larger remnant blocks, although they hunted across open ground (authors, pers. obs.).
distribution of the different groups along William's Creek, shows that high numbers of all three groups occur in the larger "Forest" and "Copse" patches right along the creek. We were surprised to find Atherton Scrubwrens and Grey-headed Robins along the creek. Hitherto we had considered these species to be strictly tied to rainforest and highly unlikely to be found in such remnant habitat. The Atherton Scrubw.ren occurred in patches 44 and 23; its identity was confirmed by mist-netting. Greyheaded Robins occurred in "Forest" patches 2, 32 and 33 and "Regeneration" patch 38. The results of the UPGMA are given in Figure 3. The patches have been assigned to five groups (1 to 5 on Fig. 3). Group 5 is quite dissimilar to all other sites and consists of a set of six patches (four Regeneration, one Forest and one Copse) in which few birds species were recorded (Appendix). Groups 3 and 4 cluster together as a larger grouping and are quite dissimilar to Groups 1, 2 and 5. Group 3 consists of 11 patches of which eight are Forest patches and Group 4 is the windbreaks.
Type
1
(Il!
(ll
28
(RJ
30
(H)
37 41
(Il]
27
(G)
28
(R]
15
(L)
42
(11)
17
(R]
19
(R)
6
(L)
40
(L)
3
eL)
45
lL)
(RJ
13
(LJ
34
lLl
33
(F)
44
(C)
2
[n
25
(F]
24
(F)
23
The number of species recorded in each patch varied from 2 to 39 with the highest in patches 10 and 14, a remarkably high number considering their areas are only 0.15 and 0.05 ha respectively. Both are close to "Pelling's" and the high species richness of the RFl, RF2 and MH groups could be due to their proximity to the larger remnant. However, patch 10 had only two RFI species, compared with seven in patch 14 which is further away and had a larger number of GR species. This difference may be due to the opening up of patch 10 by cattle (see above). Considering all the patches as a whole there is no obvious tendency for high species numbers for any group to be on patches close to "Pelling's" remnant block. Examination of Figures 2a-f which illustrate the
14
(F]
26
(F)
32
(F]
10
(F)
18
(el
8
(F)
21
(R)
16
(R)
22
(11;
31
[Hi
11
lel
0.2420
--~
0.4436
0.6452
O.846H
1.048
