O Juvenile Plumage of Javan Crested Honey Buzzard, with Comments On

Sexing of juvenile Montagu’s Harrier tributed and less evenly spaced, creating a pale blackish-brown. In nestlings, the iris is perhaps ‘boomerang’ (like in juvenile Pallid Harrier similarly coloured as the pupil or a shade paler; C macrourus ) more often than in juvenile male. after fledging, the iris becomes gradually paler The dark secondaries are darker on the underside but, throughout the first year, it is still brown (cf and, on average, also darker on the upperside, Clarke 1996, Forsman 1999). with more obvious dark bars. On the upperwing, the primaries are generally darker, with a less grey Acknowledgements wash and less obvious pale primary base; con- I thank Daniele Aliffi, Maurizio Azzolini, Valerio sequently, in flight, there is a less obvious contrast Cappello, Carmela Cardelli, Roberto Gildi, between the dark secondaries and the pale prima- Marcello Grussu, Carmelo Iapichino and Marco ry base. As already described, the axillaries and Preziosi for their help; and the bird hospitals I the greater underwing-coverts have distinct dark visited for permitting me to photograph the in- marks. Only rarely, these marks are less distinct, jured Montagu’s Harriers in their care. with a pattern similar to that of juvenile male. The white rump-patch is normally more extensive, References broader than in juvenile male. The tail is in most Clarke, R 1996. Montagu’s Harrier. Chelmsford. cases darker than in juvenile male, with darker Forsman, D 1995. Field identification of female and rectrices having darker and more obvious bars, juvenile Montagu’s and Pallid Harriers. Dutch Birding 17: 41-54. especially on the outer rectrices. The central rec- Forsman, D 1999. The raptors of Europe and the Mid- trices never show a grey wash as in juvenile male. dle East: a handbook of field identification. London. Lontkowski, J 1995. Die Unterscheidung von Korn- Bare parts Circus cyaneus , Wiesen- C. pygargus und Steppen- The iris is distinctly darker than in juvenile male, weihe C. macrourus . Limicola 9: 233-275. ranging from dark-brown to warm-brown or Andrea Corso, via Camastra 10, 96100 Siracusa, Italy ([email protected]) Juvenile plumage of Javan Crested Honey Buzzard, with comments on mimicry in south-eastern Asian Pernis and Spizaetus species S (Bas) van Balen, Resit Sözer, Vincent Nijman, Rona Dennis, Eric Meijaard & Paul R Jepson n 16 October 1995, when travelling be- for documentation and identification purposes. Otween Pelabuhanratu and Bogor, West Java, Three weeks later, the bird was still present and Indonesia, Rona Dennis and Eric Meijaard dis- Paul Jepson took additional photographs. How- covered an immature raptor at a roadside bird ever, examination by Bas van Balen and Reflit market. Initially, the bird was thought to be an Sözer of the taken photographs showed that it immature Javan Hawk-eagle Spizaetus bartelsi was not an immature Javan Hawk-eagle or an- and, because of the protected status of raptors in other Spizaetus (or Hieraaetus ) eagle but a juve- Indonesia in general and of this rare raptor en- nile Javan Crested Honey Buzzard Pernis ptilo- demic to Java in particular, it was photographed rhyncus ptilorhyncus , another (very) rare raptor 192 [Dutch Birding 21: 192-198, 1999 ] Juvenile plumage of Javan Crested Honey Buzzard endemic to Java which, according to del Hoyo et TAIL Undertail-coverts buff-cinnamon. Base of under- al (1994), may be close to species threshold. side of tail white (rest of tail hardly visible on photo- As no descriptions or illustrations of the juve- graphs). nile plumage of Javan Crested Honey Buzzard BARE PARTS Iris brown, no obvious contrast with pupil. Orbital ring white to dirty-white. Upper mandible grey- are available in the literature, and in view of its ish; lower mandible whitish, greyish towards tip; cere confusing resemblance to the immature plumage bright yellow. Tarsus and foot pale yellow, talon black. of the sympatric Javan Hawk-eagle, it seems use- ful to publish the compiled description of the photographed juvenile Javan Crested Honey Identification Buzzard and to discuss its identification. Further- The unfeathered tarsus and the long narrow head more, it seems appropriate to comment on mim- excluded the possibility that the photographed icry in south-eastern Asian Pernis and Spizaetus raptor was a Javan Hawk-eagle or another species. Spizaetus (or Hieraaetus ) eagle. In fact, the short The data presented in this article are largely unfeathered tarsus, the long narrow head with derived from observations done during field stud- the weak bill and the yellow cere only fitted ies by the authors throughout the Indonesian part Crested Honey Buzzard. The long, sooty-black of the ranges of Crested P ptilorhyncus and and pale-tipped crest was typical of juvenile Barred Honey Buzzards P celebensis (ie, Bali, Javan Crested Honey Buzzard. Presumably, it Java, Kalimantan, Sulawesi and Sumatra) in the was a recently fledged bird on account of the period of 1980-98. ‘simultaneously growing’ crest-feathers and ‘very short’ tail (Kees Roselaar pers comm). The partly Description sooty-black head and the plain buff-cinnamon The description is based on the photographs underparts strongly resembled those of immature taken of the juvenile Javan Crested Honey Buz- Malaysian Crested Honey Buzzard P p torquatus zard. Also, comparisons were made with skins of (of which skins were studied at Museum Zoologi- Javan and other Crested Honey Buzzards in the cum Bogoriense). The white pattern on the head collections at the National Museum of Natural is also found in immature Siberian Crested History, Leiden, the Netherlands, and at the Mu- Honey Buzzard P p orientalis . Apart from the seum Zoologicum Bogoriense, Bogor, Indonesia. long crest, Javan and Malaysian Crested Honey Buzzards differ from the almost-crestless Siberian STRUCTURE Head long and narrow, with long and Crested Honey Buzzard by the structure of the erect crest. Tail (very) short, apparently still growing. feathers of the upperneck: broad and rounded in Bill weak. Tibia feathered (‘trouser’); tarsus short (about Javan and Malaysian Crested Honey Buzzards as long as middle toe) and unfeathered, talon slightly and long and lanceolate in Siberian Crested curved. HEAD Forehead with white frontal band. Crown much Honey Buzzard (M E G Bartels in litt in van darker than in any Javan Hawk-eagle, forecrown pre- Heurn & van Heurn 1923). dominantly sooty-black and hindcrown (especially The sooty-black pattern on the head and the more central part) distinctly paler and browner. Crest sooty-black crest were more like an adult Blyth’s sooty-black, shorter feathers with brown tip and longer Hawk-eagle S alboniger or even a Rufous-bellied ones with whitish tip. Nape and rest of neck buff- Eagle H kienerii but the buff-brown neck (includ- brown, feathers with dark centre (shaft-streak) (ap- ing the nape) made the bird look more like a proaching buff-cinnamon of underparts). Lore whitish, Javan Hawk-eagle, especially when seen from lore-feathers seemingly scaly (not clearly visible on the aside or from behind. photographs). Ear-coverts brownish, with black ‘cres- cent’ below eye and black spot at rear edge, and sur- rounded by white line, running from rear corner of eye Status on Greater Sundas down around ear-coverts to base of bill. Chin and thro- As already mentioned, Javan Crested Honey at whitish, showing traces of black outline or mesial Buzzard is endemic to Java. There are only two stripe typical of adult Javan Crested Honey Buzzard skins of Javan Crested Honey Buzzard among the (chin- and throat-feathers seemed to be damaged or 50 skins of Crested Honey Buzzard in the Bartels were moulting). collection from Java brought together between UPPERPARTS Dark brown, feathers with pale brownish fringe. 1898 and 1942 (René Dekker pers comm), sug- UNDERPARTS Plain buff-cinnamon, feathers with slight- gesting that Javan Crested Honey Buzzard has ly darker shaft-streak. ‘Trouser’ pale buff to whitish. always been (very) rare. However, van Heurn & WING Primaries blackish-brown. Secondaries, tertials van Heurn (1923) reported the presence of no and wing-coverts dark brown with pale brown fringe. less than 14 skins (and one egg) of Javan Crested 193 Juvenile plumage of Javan Crested Honey Buzzard Honey Buzzard in the Bartels collection (now at Pernis exhibit the highest local variability in National Museum of Natural History). The 12 plumage colour and pattern among raptors missing skins may have got lost during World War world-wide, including dark morphs in some taxa II. Four skins of Javan Crested Honey Buzzard are (del Hoyo et al 1994). The general trend of this at Museum Zoologicum Bogoriense. It should variation in Crested Honey Buzzards is for the also be pointed out that well-documented field taxa inhabiting tropical forests to be darker or records of Javan Crested Honey Buzzard are rare. more richly barred in adults, with a crest and a black gorget surrounding a whitish throat to be Convergent evolution or mimicry common; immatures are paler than adults but Immature Javan Crested Honey Buzzard may browner than in the more northern taxa (Brown cause confusion with immature Javan Hawk- & Amadon 1968). eagle. Apart from the above-described similari- As first described for Sulawesi by Meyer & ties in plumage, the flight silhouettes are also Wigglesworth (1898), in the Indo-Malayan and similar. Both raptors are confined to Java and Philippine archipelagos, plumage colour and have not been recorded on any of the off-lying pattern of geographically distinct populations of islands like, for instance, Bali, Kangean and Barred and Crested Honey Buzzards closely Madura. Although few data are available, Javan resemble those of sympatric hawk-eagles, either Crested Honey Buzzard and Javan Hawk-eagle in adult plumage, as on Borneo and Sumatra, or seem to be confined to primary and secondary in immature plumage, as on Java, or in both rain forests.

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