Javan Hawk-eagle

The Javan Hawk-eagle, Spizaetus bartelsi is a medium-sized, approximately 61cm long, dark brown raptor in the family Accipitridae. It has a long crest, rufous head and neck, and heavily barred black below. The crest is black with white tip. Both sexes are similar. The young is duller and has unmarked underparts.

An Indonesian endemic, the Javan Hawk-eagle is distributed in humid tropical forests of Java. Because of the plumages variability of Spizaetus eagle, the Javan Hawk-eagle was not recognised as a full species until 1953.

One of the rarest of all raptors, the Javan Hawk-eagle is believed to be a monogamous species. The female usually lays one egg in nest high on top of forest trees. The diet consists mainly of birds, lizards, fruit bats and mammals.

The Javan Hawk-eagle is the national bird of Indonesia. The scientific name commemorates Hans Bartels.

Due to ongoing habitat loss, small population size, limited range and hunting in some areas, the Javan Hawk-eagle is evaluated as Endangered on the IUCN Red List of Threatened Species. It is listed on Appendix II of CITES.

DIAGNOSIS

Typical hawk-eagle with prominent crest. Distinguished from adult crested subspecies of Javan Crested Hawk-eagle Pernis ptilorhyncus ptilorhyncus by larger size (60-70 cm versus 50 cm) and the much more prominent crest of S. bartelsi , and the characteristic long narrow head of P. ptilorhyncus. Juvenile plumages of S. bartelsi and P. ptilorhyncus show a confusing resemblance but the latter differs by its short unfeathered tarsus, and long narrow head with weak bill and yellow cere. Other possibly confusing eagles are Changeable Hawk-eagle Spizaetus cirrhatus (larger, just vestigial crest), Rufous-bellied Hawk-eagle Hieraaetus kienerii (smaller, shorter crest, whiter below, dark mask), Aviceda jerdoni (smaller, whiter underparts, bare legs),Wallace’s Hawk-eagle Spizaetus nanus (smaller, tail with three black bands), Sulawesi Hawk-eagle Spizaetus lancoelatus (crestless), Booted Eagle Hieraaetus pennatus (smaller, crestless), See also the description of these species in this guide


DESCRIPTION

Medium sized eagle (adults 60-70 cm) Sexes similar but female ON AVERAGE larger in size. Adult: Dark-brown upperparts, head chestnut-brown, nape yellow-brown. Dark brown to black feathered crown with thin buf margins, prominent white-tipped black crest. Tail dark brown with four black bands, terminating in a thin white band. Underparts whitish to pale rusty-white, white throat emphasized by dark brown to black moustachial and mesial stripes. Breast marked with bold blackish drops and traces of rufous bars, belly and legs barred dark brown. Tail buffy grey with four grey

brown bands and a white margin. Tarsus white-feathered with feathers covering the base of the feet. Iris yellow, dark grey to black bill with grey cere, feet yellow.

Juvenile/Sub-adult: Upperparts lighter than in adult. The crest, coloured as in adult, shorter but visible. Underparts, head and crown cinnamon-brown, breast and underwings gradually turning white when tail bands and body stripes have fully developed. Lacks the moustachial, mesial and underpart marking and (except for the terminal) tails-bands which gradually develop the following years. Striping appears first near the legs and flanka. Iris bluish-grey gradually turning yellow in second-year birds.