DOI: 10.18195/issn.0312-3162.23(2).2006.115-132 [<ecords o{ the rVcstCrJJ Australian Museum 23: 115~ n2 (2006). The birds of Gag Island, Western Papuan islands, Indonesia R.E. Johnstone Western Australian Museum, Locked Bag 49, Welsh pool DC Western Australia 6'1S6 Abstract This report is based mainly on data gathered during a biological survey of C;ag Island by a joint Western Australian Museum, Museum Zoologicum Bogoriense and Herbarium Bogoriense expedition in July 1'197. A total of 70 species of bird have been recorded for Gag Island and a number of these represent new island and/or Raja Ampat Archipelago records. Relative abundance, status, local distribution and habitat preferences found for each species arc described, extralimital range is outlined and notes on taxonomv are also given. No endemic birds were recorded for Gag Island but a number of species show significant morphological variation from other island forms and may prove to be distinct taxonomically. INTRODUCTION undergo geographic variation for taxonon,ic, Gag Island (0025'S, 129 U 53'E) is one of the Western morphological and genetic studies. The Papuan or Raja Ampat Islands, lying just off the annotated checklist provided covers every Vogelkop of Irian Jaya, between New Guinea and species recorded, both historically and during Halmahera, Indonesia. These islands include (from this survey. north to south) Sayang, Kawe, Waigeo, Gebe, Gag, In the annotated list I summarise for each species Gam, Batanta, Salawati, Kofiau, Misool and a its relative abundance (whether it is very common, number of small islands (Figure 1). Gag Island is common, moderately common, uncommon, scarce separated from its nearest neighbours Gebe Island or rare), whether it feeds alone or in groups, status to the north~west, and Batangpele Island to the (a judgement on whether it is a vagrant, visitor or north-east, by about 40 km of relatively deep sea. resident), habitat preferences and breeding season. Gag Island is roughly oval shaped 12 km long by 7 Extralimital range is also briefly outlined and for km wide with its longest axis directed N-S and with those species that are recognised as undergoing a surface area of 56 km2 (Figure 1). The east coast is geographical variation, taxonomic notes have been deeply indented by the shallow Gambir Bay, which provided. penetrates about 1.5 km inland. Most of the coast is rocky but there are a number of sandy beaches on Habitats the northern and western sides. Gag Island consists Eleven major habitat types were recognised on mostly of undulating hills, the highest peak Gag Island. Gunung Susu rising to 3]] m. The island contains a I. Marine. Includes coastal seas, stacks, reef flats number of small rivers and creeks including the and sandy. and rockv. shores. Musawalo River in north and the Wapob River in 2. Kebun. Cultivated areas, mainly coconut east draining into Gambir Bay. Sago swamps and plantations but also banana, taro, breadfruit fresh water springs are abundant including a fairly and mango etc (Figure 2). large spring fed lagoon in the south-west corner. 3. Disturbed \'olcanic forest. Mostlv secondary There is a small village on the north side of Gambir forest backing kebun in northern part of island Bav and a number of residents at Kampung Tua on (Figure] ). the northern coast. Domestic goats and domestic 4. Primal'\' volcanic forest. Lowland rainforest fowl occur throughout the cultivated areas and do covering most of the northern third of the not appear to have greatly disturbed the vegetation. island. Tall luxuriant forest with a variable Gag Island was visited bv the joint Western canopy, 30~35 m with enwrgents to 45 m. Australian Museull1, Museum Zoologicum Dominant genera include Diospyros sp., Bogoriense and Ilerbarium Bogoriense group Sterulia longitolia, Planchonella sp., Celtis between 9 and 20 Julv 1997. The major aim of philippensis, Tricalysia malaccensis, Canarium the preliminary bird survey was to document the littorale and Champereia manillana (Figure 5). avifauna of the island and provide data on local J. Sago vegetation. Fairly extensive stands around distribution, status and habitat preferences. A Cambir Bay and along Wapob River. small collection was also made of species that 6. Grassland. Includes airstrip, open grassv areas 116 R.E. Johnstone 4000mE 6000mE 8000mE 10000mE 12000mE Kampung Tua Daniki ~---- Gag Island 12000mN 12000mN Turtle Beach -" .. .._ . .......... ' ...... : 10000mN i 10000mN :.~""'.) _.""_ {.. 1...... \ .... \'. ............_.. ~~I. .. .....,./~.. _............. Gambir bay 8000mN 8000mN "'-.-- ,.\Camp I. .•., .. 6000mN 6000mN 4000mN 4000mN Fresh Water Pond 2000mN 2000mN .b~WAIGEO Gebe island , • • Gag island ••r' ,. s orong '. Batanta ~ ~t ~.r True North Local Grid ~ sala~atiIRIAN •. JAYA 500 0 500 1000 1500 2000 Metres .•' I< I 4000mE 6000mE 8000mE 10000mE 12000mE Figure 1 Map of Gag Island showing main features. around settlements and grassy hills On the 8. Beach vegetation. Ranging from dense closed south-east corner of island. (Figures I, 3 and 6). forest to open disturbed or partly cultivated 7. Mangroves. Small stand of mangroves occurs areas. Dominant plants include Barringtonia, at mouth of a creek at Camp Two (south-east Calophylll1m, Casl1arina, Scaevola, Pandanl1s, side of island). Genera include Sonneratia, Tournefortia, Trema, Flagellaria, Hibiscus and Ll1mnitzera, Ceriops, Brugl1iera, Xylocarpl1s, Terminalia (Figure 7). Rhizophora and Exoecaria. Birds of Gag Island 117 Figure 2 Gambir Bay, with BHP Camp on right and village backed by kebun on left. Figure 3 Airstrip with rank herbage and kebun. 118 R.E. Johnstone 9. Ultra basic valley forest. Tall rainforest occurring in valleys of southern two-thirds of the island. Dominant trees include Dillenia, HorsEieldia, Buchanania, Eugenia and Clerodendrum (Figure 4). 10. Ultrabasic slope forest. Ranging from dense forest to open forest and scrub and occurring throughout the southern two-thirds of the island. Dominated by Gamau Ploiarium sessile, Calophyllum, Symplocos and Clerodendrum sp. 11. Ultra basic ridge scrub. Ranging from areas of open shrubland and woodland to dense thickets. Occurring throughout the southern two-thirds of the island. Dominated by short and sparsely distributed Gamau Ploiarium sessile, Calophyllum articulatum, Planchonella oxyedra and Clerodendrum sp. Climate Gag Island has a tropical monsoon type climate, characterised by year-round moderate temperatures and high relative humidity. Its climate is influenced by the south-east trade winds from May to October and the north-west monsoons from December to April. The wet season (north-west monsoon) begins in October, peaks in December-January and may continue until April. Mean daily temperatures vary between about 21 0 and 34 0 C. Figure 4 Rainforest near pit 8. Figure 5 Disturbed volcanic forest along track to Turtle Beach. Birds of Gag Island 119 Figure 6 Grassland of Alang alang south of Camp 2. Figure 7 Lagoon, south-west corner of island. Ornithological History by Peters (1967) and Sibley and Monroe (1990) in The ornithological history of Gag Island is their world distributional lists but their source is rather sparse. The famous naturalist explorer A.R. however unknown; la ter F. Crome (1997) Wallace spent several days on the island and compiled a list of 39 species for Gag Island (based collected a small number of specimens on Gag on literature records). As visits to Gag Island had Island (Gagie) in early 1860s; Or H.A. Bernstein been of short duration and very infrequent its also made a small collection on the island in 1863 avifauna was poorly known. This survey did not and 1864; Or J. Diamond and D. Bishop visited record eight of the birds previously listed for the the island for a day in 1986. Apart from their island, but added a further 24 species (see Table records several species are listed for Gag Island 1). 120 R.E. Johnstone ANNOTATED SPECIES LIST Extralimital range. Shores of east Indian Ocean Classification and nomenclature follows Andrew and west and central Pacific. Widely distributed in (1992) and White and Bruce (1986) and Johnstone the region including remote atolls. (2001). An/ea ibis coromanda Cattle Egret Fregatidae Historical records. Previously listed for Gag Island but not recorded during the July survey. Fregata minor Great Frigatebird Also recorded from northern Moluccas and Eight birds off Turtle Bay on 11 July, also listed Western Papuan, Waigeo and Yamna Islands. for Gag Island in 1860s. Extralimital range. From southern and eastern Extralimital range. Widespread in Indian and Asia south-east to northern and eastern Australia Pacific Oceans, also south Atlantic Ocean. and New Zealand. Only recently extended its range Moderately common around Ambon and around to include New Guinea. Records from northern Kai and Tanimbar Islands. (R.E. Johnstone Moluccas and Western Papuan islands. In eastern unpublished data). Wallacea dated specimens fall between September- November. Fregata ariel Lesser Frigatebird Four following coast north-west corner of island Accipitridae on 11 July and 10 over southern tip of island on 20 Osprey July. These are the first records for Gag Island. Pandion haliaehls cristatus Extralimital range. Breeding on tropical islands in Moderately common. Ones and twos recorded Atlantic, Indian and Pacific Oceans. Widespread over northern end of island, at Gambir Bay, at and moderately common in western Papuan region. Camp Two and over lagoon at south-west corner of island. Previously listed for Gag Island and resident Sulidae judging from a recently used nest in tree near airstrip. Sula sula Red-footed Booby Extralimital range. This subspecies ranges from A beach washed skeleton found on north-east side Philippines and Sumatra south-east to Australia and of island in July. A wide ranging species occurring New Caledonia. Widely distributed in coastal areas throughout tropical seas. around New Guinea. Taxonomy. The subspecies melvillensis is Ardeidae sometimes recognised for the birds from Indonesia, Egretta alba Great Egret the Philippines, northern Australia and New Caledonia and cristatus for southern Australia and One feeding on airstrip with two Intermediate Tasmania.