Australasian Grebe Tachybaptus novaehollandiae Scientific name definitions

23–27 cm; 100–230 g. Nominate race in breeding  plumage has head and neck dark brown-grey, often more blackish on head, sometimes slightly paler on foreneck, with large chestnut or maroon-chestnut crescentic patch above ear-coverts and to sides of middle neck; upperparts dark brown-grey, upperwing similar except large white panel on remiges covering most of secondaries and basal primaries; underwing pale grey also with same large panel on remiges; chest dark brown-grey, sides and flanks similar but with much tawny admixed, rearmost underparts near tail rather dull whitish buff, abdomen white; iris yolk-yellow; bill black with whitish tip and broad yellow or greenish-yellow patch at gape; legs dark greenish grey, yellowish grey on inner tarsi. Non-breeding adult  has dark brownish-grey cap, central hindneck and upperparts; side of head and most of neck pale tawny to grey-buff, usually whiter on face, chin and upper throat, and upper ear-coverts often diffusely greyish; tawny-buff with some greyish on sides and flanks; most of bill paler. Non-breeding adult very similar to T. ruficollis, but iris yellow and has more white in wing; in breeding plumage separated also by less extensive chestnut on head and neck (not reaching throat and foreneck). Sexes similar in plumage. Juvenile  similar to non-breeding adult, but face and neck striped blackish and whitish, eye duller. Races differ only slightly, mainly in size and coloration: incola like nominate, but flanks slightly warmer; <em>rennellianus</em>  longer-billed than others, has chestnut on head darker, extensive white in wing; leucosternos has lower breast pure white, much white in wing; javanicus and fumosus resemble nominate, but variable, and probably indistinguishable; timorensis reported to be like nominate, but underparts darker and more tawny-washed, and bill rather large, though differences (if any) minimal.

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Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Wide range of waterbodies, mainly freshwater and permanent or semi permanent; often on temporary floodwaters; typically found on small reservoirs at farms. Especially during breeding , prefers vegetated shores . Lowlands and hills, generally to c. 1500 m; to at least 3200 m in New Guinea (Snow Mts).

Poorly known. Possibly resident in E & SW Australia, migratory in N and dispersive in arid interior; in very dry years, some move towards coast. Recent colonization of New Zealand and rapid occupation of temporary waterbodies inland indicate extensive movements, with long-distance flights, probably at night. Ringing records reveal movements of up to 338 km. Vagrant in Admiralty Is (Bismarck Archipelago) and Moluccas.

Mainly small fish (Philypnodon grandiceps, Gambusia affinis, Hypseleotris klunzingeri), freshwater molluscs, aquatic insects and crustaceans; also snails (Gastropoda), which generally shunned by most members of family. Catches prey by making deep dives and surface chases; sometimes associates with ducks, coots (Fulica) and moorhens (Gallinula), capturing invertebrates that they flush. One seen diving in association with a freshwater turtle (3 Gosper, C.R. (2008). A foraging association between an Australasian Grebe and a freshwater turtle. Austr. Field Orn.. 25: 46. Close ).

A fast metallic trill, somewhat wavering , given by both sexes, especially during breeding; rennellianus perhaps marginally faster. Alarm a sharp “pit” or “bik”.

Season prolonged, laying Aug–Apr, a result of opportunistic breeding on temporary waters; on permanent waters breeds mostly in spring, laying Sept–Nov in SE Australia, and in tropical regions may breed throughout year; up to three breeds in a season. Solitary. Nest a floating platform of plant matter anchored to submerged vegetation. Clutch 1–9 eggs, usually 4–5 (larger clutches perhaps product of two females); incubation period c. 23 days; chicks  have dark brown down with pale stripes on upperparts , and white and grey-brown underparts; fledging period c. 8 weeks. Breeding success thought to be relatively low. Likely predators are Dusky Moorhen Gallinula tenebrosa and Purple Swamphen Porphyrio porphyrio (4 Mo, M. and Waterhouse, D.R. (2015). Responses of brooding Australasian Grebes Tachybaptus novaehollandiae to other waterbirds. Australian Field Ornithology. 32(4): 176–182. Close ).

Not globally threatened (Least Concern). Locally common within its reasonably large range. Global population not known, believed to be c. 500,000 individuals, but showing an increasing trend. Generally common in Australia, especially in SW, E & SE, and numbers apparently stable; small population in Tasmania, with fewer than ten adults reported annually in 1972–1988. Small breeding population established in New Zealand during early 1970s, apparently now in decline; found mainly at widely scattered sites on North I, where up to 15 at L Rotokawau (near Rotorua). Common in New Guinea, with 264 censused in Papua New Guinea in Jan 1991. Rare in Java (except at Rakoetak, SE of Bandung, where common, at least formerly) and Bali; status in Lesser Sundas uncertain, possibly only a non-breeding visitor. Much more widespread in Vanuatu than previously thought. Island races javanicus, fumosus, timorensis and <em>rennellianus</em> may have very small populations, and thus potentially be at risk: apparently no recent records of fumosus, but very small population may survive in crater lake of Mt Awu, in N Sangihe; very few recent records from Timor, where timorensis seems to be rare, but situation complicated by difficulties of distinguishing this species from far commoner T. ruficollis (5 Trainor, C. R. (2011). The waterbirds and coastal seabirds of Timor-Leste: new site records clarifying residence status, distribution and taxonomy. Forktail 27:63–72. Close ); on Roti I (off SW Timor), at least four (together with c. 45 T. ruficollis) at L Oendui, in Tapuafu peninsula, in Dec 2004 (6 Trainor, C. R. (2005). Birds of Tapuafu Peninsula, Roti Island, Lesser Sundas, Indonesia. Forktail 21:121–131. Close ). Records from Tanimbar Is (7 Coates, B. J., and K. D. Bishop (1997). A Guide to the Birds of Wallacea: Sulawesi, The Moluccas and Lesser Sunda Islands, Indonesia. Dove Publications, Alderley, Queensland, Australia. Close ) In Australia, some local declines or extinctions due to human modifications of wetlands, including e.g. drainage and exploitation of underground water supplies, sometimes leading also to increased salinity; on the other hand, widespread creation of artificial wetlands has undoubtedly benefited this species.