Distribution And Abundance Onthe

Australia's GBR supports a significant and diverse sea-bird community. Twenty different species (Table 31.1) comprising 1.7 millon individuals and more than 25% of Australia's tropical seabirds nest within the GBR region. This includes greater than 50% of Australia's roseate terns (S. dougallii), lesser-crested terns (S. bengalensis,

Figure 31.1 A, crested tern; B, sooty tern; C, least frigatebird; D, bridled tern; E, lesser crested tern; F, black-naped tern; G, black noddy; H, wedge-tailed shearwater; I, brown booby; J, masked booby; K, common noddy. (Photos: C. Erwin, B. Congdon, D. Peck.)
Table 31.1 Seabird species/approximate population estimates for the GBR only/nesting habitat/foraging guild

Species

population

Nesting habitat

Foraging guild

Herald petrel

Pterodroma arminjoniana

3

Ground: scrape

Pelagic

Wedge-tailed shearwater

Puffinus pacificus

560 000

Burrow

Pelagic

Australian pelican

Pelicanus conspicillatus

1024

Ground: scrape

Coastal

Red-footed booby

Sula sula

172

Trees/shrubs/ground

Pelagic

Brown booby

Sula leucogaster

18 500

Ground: low grass/scrape

Offshore

Masked booby

Sula dactylatra

1100

Ground: scrape

Pelagic

Great frigatebird

Fregata minor

20

Trees/ground

Pelagic

Least frigatebird

Fregata ariel

2500

Shrubs/ground

Pelagic

Red-tailed tropicbird

Paethon rubricauda

100

Holes/crevices/tree roots

Pelagic

Caspian tern

Sterna caspia

70

Ground: low grass/scrape

Coastal

Roseate tern

Sterna dougallii

6000

Ground: scrape

Inshore

Black-naped tern

Sterna sumatrana

3900

Ground: scrape

Inshore

Little tern

Sterna albifrons

51 (possibly up to 1000)

Ground: scrape

Coastal

Sooty tern

Sterna fuscata

48 000

Ground: low grass/scrape

Pelagic

Bridled tern

Sterna anaethetus

13 900

Ground: low grass/scrape

Offshore

Crested tern

Sterna bergii

26 000

Ground: scrape

Inshore

Lesser-crested tern

Sterna bengalensis

6300

Ground: scrape

Inshore

Common noddy

Anous stolidus

46 000

Ground: low grass/scrape

Offshore

Black noddy

Anous minutus

300 000

Trees

Offshore

Silver Gull

Larus novaehollandiae

750

Ground: low grass/scrape

Coastal

Fig. 31.1E), black-naped terns (S. sumatrana, Fig. 31.1F), and black noddies (Anous minutus, Fig. 31.1G), and about 25% of the wedge-tailed shearwater (Puffinus pacificus, Fig. 31.1H), brown booby (Sula leucogaster, Fig. 31.11), masked booby (S. dactylatra, Fig. 31.1/) and red-tailed tropicbirds (Phaeton rubricauda).

In general, seabirds are colonial nesters. Throughout the GBR there are 56 major and 20 minor seabird colonies (Fig. 31.2). Most major colonies are located in either the far northern, northern or far southern regions of the GBR. Raine Island in the far northern sector is one of the largest and most significant tropical seabird breeding sites in Australia. Of the 24 seabird species recorded as breeding in Queensland, 14 breed at Raine Island. A comprehensive review of the trends in seabird numbers at this site since the beginning of last century has recently been undertaken (see Additional reading).

Michaelmas Cay in the northern section of the GBR is a tropical seabird colony rated as the second most important bird nesting site in the GBR. The island constitutes a major nesting site for sooty terns and common noddies (A. stolidus, Fig. 31.1K), as well as for

Figure 31.2 Seabird colony distribution on the GBR. (Map: Spatial Data Centre, GBRMPA.)

crested and lesser-crested terns. The islands of the Swain reefs in the far south-eastern region of the GBR also constitute one of six core seabird breeding areas.

Finally, the Capricorn-Bunker group of islands in the far southern GBR contains nationally and internationally significant seabird breeding populations. This island group supports the Pacific Ocean's largest breeding colony of wedge-tailed shearwaters and over 97% of the black noddy populations of the GBR. The Capri-cornia Cays also contain ~75% of the seabird biomass of the GBR World Heritage Area.

Many seabird species that breed within the GBR and in adjacent areas are considered migratory and/ or threatened species and are listed under the Australian Environmental Protection and Biodiversity Conservation (EPBC) Act 1999 in a variety of categories. Many are also variously protected under international agreements such as: the China-Australia Migratory Bird Agreement (CAMBA), Japan-Australia Migratory Bird Agreement (JAMBA) and the Convention on the Conservation of Migratory Species of Wild Animals (Bonn Convention 1979). Additionally, the GBR region hosts migrating populations of some northern hemisphere breeding species such as common tern (Sterna hirundo) and much of the Asian population of roseate tern.

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