DISTRIBUTION – New Britain Sparrowhawk (Accipiter brachyurus) is Australasian little known and generally regarded as rare but may well be commoner than the few records suggest. New Guinea: like Slaty-backed Goshawk, it long thought endemic to New Britain (second the largest island of Papua New Guinea), but in the 1990s discovered also in southern New Ireland (still part of Bismarck Archipelago), where it was the least uncommon raptor in the montane forests.
MOVEMENTS – New Britain Sparrowhawk is presumably sedentary, though juveniles may well wander.
HABITAT – Lives in tropical to subtropical moist forest, also forest edge and partly cleared areas, in New Britain; montane forest in New Ireland. Sea-level to 900+ m in New Britain, at an altitude of 1,200–1,800 m in New Ireland. The major threat to this species is habitat destruction, eventually declining its number in lowland forests.
IDENTIFICATION – New Britain Sparrowhawk is small to smallish accipiter, blackish, gray, and rufous as an adult. It has a fairly heavy bill, long thin legs, and toes, relatively pointed wingtips, and a very short tail. Both sexes are similar, but females may be nearly 20% larger; juvenile distinct.
Some juvenile molts into the distinct immature stage, but identification was based on the combination, with immature plumage, of the rufous collar, barred breast, and dark red eyes not found in any other known New Britain accipiter: in view of paucity of knowledge of that island’s raptors, perhaps description may refer to molting juvenile of as yet undescribed species.
Perched Adult All plain dark slate above, with blacker crown and greyer cheeks, apart from bright rufous nuchal collar; mainly pearl-grey below, shading into white crissum, but throat greyish-white and sides of chest tinged rufous. Juvenile Rufous above, with blackish blotches from dusky feather centres and dusky bars on the slightly grey-tinged tail.
But crown blacker with narrow rufous edges and some white showing through, particularly on nape; cream to pale buff below with broad and diffuse brown streaks, these becoming drops and arrowheads on the abdomen and wavy bars on thighs. (Supposed immature stage dark brown above with darker bars, indistinct on the tail, but dark brownish-grey head and rufous collar; white below, barred rufous on breast and wing-linings but not the abdomen.) Bare parts Adult eyes dark red, juvenile brown.
Adult care greenish-yellow, juvenile greenish. Adult legs are yellow to orange-yellow, juvenile paler yellow. (Supposed immature had dark red eyes and, unexpectedly, orange cere and legs.) Flight Small raptor with accipiter proportions, but short and relatively pointed wingtips and, for this genus, exceptionally short tail; even so, wingspan only 1.8 times total length.
Adult All blackish-slate above with rufous collar; and largely gray below, mottled dusky on wing-linings, with slightly darker plain gray tail, contrasting white under tail-coverts and whitish-barred flight-feathers tinged rufous at the base. Juvenile very rufous above blotched and barred blackish, with dark head; buff-white below with heavy brown streaks, narrower on wing-linings, and flight-feathers and tail pale rufous with thin dark bars.
RELATED SPECIES – A combination of blackish and gray with a rufous collar, as well as red eyes and yellow legs should be unmistakable, while the very rufous juvenile is also distinctively streaked below. Four other accipiters are found in New Britain, though this and New Britain Goshawk are so little known that as yet undescribed accipiters may well still await discovery in this or other forested parts of the Indonesian and Papuan areas, where nearly 30% of all accipiters are endemic.
Of these, Slaty-backed Sparrowhawk is most similar in size and pattern but has more rounded wings, a slightly longer tail, creamier underparts, richly orange eyes, and legs, and no rufous collar, while juvenile ‘kestrel-patterned’ above and heavily barred rufous and brown below.
Not dissimilar in appearance, at least as an adult, New Britain Goshawk is clearly larger, paler above and white below, again with orange eyes and legs. The last two species, New Britain race (dampieri) of widespread Varied Goshawk (adult pale gray and pink, juvenile brown above, streaked and barred below) and much larger and longer-winged Meyer’s Goshawk (adult black and white, usually somewhat streaked and barred below, or all black, juvenile dark brown above, edged rufous, and all rufous-buff below with sparse narrow dusky streaks), should present no difficulties.
VOICE – Not described.
FOOD – Not recorded, but foot structure and a considerable degree of RSD indicate bird-eater.
SOCIOSEXUAL BEHAVIOUR – Probably solitary or in pairs. No description of displays.
BREEDING – New Britain Sparrowhawk is a very rare bird, and very little is known about the breeding.
POPULATION – New Britain Sparrowhawk is a threatened species in the birds of prey. Though provisional order of magnitude here put in the upper hundreds, this rather small forest accipiter could well be somewhat less rare than supposed and, indeed, BirdLife International suggests that it may belong in the 1,000 to 2,499 range. Extensive logging (often followed by planting of oil palms) is destroying its lowland habitats, but the montane forests are not apparently threatened.
Its recent detection in southern New Ireland raises the possibility of further discoveries in both islands. The New Britain population is known from a few records up to at least 900 m’, but perhaps the higher montane forests have not been adequately surveyed. The two islands have a combined area of over 50,000 km2, with significant sections above 1,000 m.
GEOGRAPHICAL VARIATION Monotypic. Forms a superspecies with Collared and Moluccan Sparrowhawks.
MEASUREMENTS. New Britain Sparrowhawk is 27 to 34 cm long.