General

The three species of genus Butastur are mid-sized lightly built raptors, with long, narrow wings and mid-length tail. The shape has some reminiscence to Buteo buzzards and harriers, and even to Accipiters and falcons. They are easy to identify if seen reasonably well. Adults have conspicuous pale eyes. When perching, White-eyed and Grey-faced may be confused with Buteos, especially Steppe Buzzard, but the throat pattern is different, as well as adult eye colour. First-year birds do not show the breast-band of Buteos, and show variable streaky pattern on upper breast with lower underparts whitish (Buteos tend to have dark belly-patches).

Distribution

Resident from Indian SC to Myanmar.

Life cycle

Breeds during northern spring, from February to May.

General

Similar in shape to other Butastur, with longish tail and long wings. Slightly blunter wing tips than in Grey-faced Buzzard.

Adult

Head is dark brown, except contrasting white throat with black mesial and moustachial stripes (adult Grey-faced Buzzard has more grey on head, but white throat with stripes is similar). May show a short whitish supercilium and often a white neck-patch. Eyes are very pale, almost whitish. Upper breast quite uniformly brownish, some irregular barring-like pattern of brown and whitish below that (more restricted and irregular barring than in adult Grey-faced). Underwing coverts quite dark brown, about as dark as the breast. Upperwing-coverts distinctly paler than the back or remiges (unlike other Butastur), uppertail reddish-brown, undertail almost uniform with only black subterminal bar (unlike Grey-faced). No differences between the sexes.

First-year

AGE: The eyes are initially almost blackish (whitish in adult). The throat-pattern less neat than in adult and supercilium more distinct, head paler, in some prominently pale, and the cap is neatly streaked. Underparts is quite different to adult: almost uniform pale rufous, paler when worn and thinly streaked black, underwing coverts mid-brown as in adult. Upperparts not very different to the adult, but may show white feathers on the mantle, and is somewhat scaly because of white feather fringes when fresh. Black on the tips of primaries less clear cut than in adult. Tail is typically more distinctly barred dark and less rufous than in adult, but may be almost unbarred. However, both remiges and rectrices are quite similar in both age classes.

SPECIES: may be confusing at first, but in fact quite distinct. Grey-faced Buzzard occurs mostly in different areas. White-eyed has quite pale head (darker with more defined supercilium in Grey-headed), neat streaks on head and underparts (juvenile Grey-faced has stronger more blotchy patterning), somewhat streaked mantle (not streaked at all in Grey-faced), pale upper wing-coverts compared to mantle (in Grey-faced dark with whitish tips or fringes) and rufous tail (greyish, more strongly barred tail in Grey-faced).

Subadult

The adult plumage is attained in the first moult, and no real sub-adult plumages. That moult commences already in the first autumn and proceeds variably so that first-year birds look partly adult, partly juvenile. More advanced birds are difficult to separate from adults, because differences in flight-feathers are slight. Eyes turn paler with age, by new year already quite pale.

Distribution

Resident locally in SE Asia.

Life cycle

Breeding during northern spring, youngs birds fresh during northern summer. Primary moult of adults is close to completion in August.

General

Similar in shape to other Butastur, but with somewhat broader and rounder wing-tips, and shorter tail. Easy to identify from colour patterns. Spends a lot of time spanning from the treetops. When soaring, wings held flat with tips somewhat lowered. Strong wing beats.

Adult

Greyish head and underparts, may show some barring (other adult Butastur have contrasting whitish area on throat and more distinct barring). Reddish-brown mantle. Reddish-brown remiges and rectrices make identification easy for both perching and in flight (White-eyed shares the reddish uppertail, but Grey-eyed has brownish, banded tail, and although both other species have reddish tone to upper primaries, neither have that as prominent as in Rufous-winged, and are more brown, less brick-red). Remiges and upper primary coverts have also black rear band (other Butastur have also black rear band on remiges, but neither on the upper primary coverts, which are dark in both). Underwing-coverts mostly whitish (may be pale in other species, but patterned). No sexual differences found.

First-year

The head is less greyish, more brownish and overall streaked much more boldly than in adult. Upperpart feathers have indistinct pale fringes. Breast is more streaked. Wing and tail feathers not much different from adult - brightly rufous and making specific identification comparatively easy.

In postjuvenile moult the aspect of plumage turns to adult like, mantle before coverts. After the body moult is complete during the first winter, difficult to age but remiges still juvenile until the first complete moult and eyes remain darkish for some time (yellowish in adult).

Distribution

Breeds in Japan, Manchuria and marginally in Russia. Migrates to winter in southern China and SE Asia.

Life cycle

Summer breeder and long-distance migrant. Wing-feather moult during the summer and it is finished on autumn migration.

General

The largest Butastur, but not very different from the others structurally. Typical of the genus with long, narrow wings. Wing strokes deep and resilient, soaring is easy-looking and light, often in flocks on migration. In quick views may be confusable to an Accipiter, but longer wings, largely pale uppertail coverts and in adult the grey head combined with white throat should make the species easily separable.

Adult

Contrasting white throat with bold black mesial and moustachial stripes (like White-eyed Buzzard). May show a whitish supercilium, but it is shorter than in first-year. Brownish breast and barred lower underparts (other species less barred). Ubderwing coverts about a dark as and similarly patterned to lower underparts (White-eyed Buzzard has most of the underwing-coverts uniformly brown, the similar tone and pattern to head-sides.) Upperparts quite uniformly greyish-brown, with black rear band on remiges and strongly barred tail (other Butastur have a complete terminal band on tail and variable, mostly incomplete internal bars). Narrow pale area on uppertail-coverts (unlike other Butastur).

First-year

Contrasting blackish ear-coverts and whitish supercilium (different pattern from adults and other Butastur). Pale underparts with irregular pattern, some bold streaking (vs adult, similar to young White-eyed). Underwing coverts about as pale and similarly patterned to body underparts. (Much darker and almost uniformn brown underwing coverts in White-eyed Buzzard). Tail with three dark bars, slightly narrower than the intervening pale bars (internal bars much narrower in White-eyed).

Subadult

The second plumage is like adult, and this species has no real subadult plumages. May moult part of the head and underparts before the first spring migration, but not as extensively as other less migratory Butastur before spring.