Spot-bellied Eagle-owl

The spot-bellied eagle-owl is a large species of owl. It measures from 50 to 65 cm (20 to 26 in) in length. It is the sixth longest owl in the world on average and has the ninth longest wings of any living owl. The widely reported weight range for this species 1.3 to 1.5 kg (2.9 to 3.3 lb) but this is probably towards the low end (possibly from B. n. blighi) or is possibly representative only of smaller males. That body mass range is similar to that of the larger race of barred eagle-owl, which are in all races considerably smaller going on total length, standard measurements and appearance. One female shot near Haputale in the Badulla District of Sri Lanka, where the owls are smaller than to the north, was found to have weighed 1.7 kg (3.7 lb). Perhaps a more correct average weight range for the species is 1.5 to 2.5 kg (3.3 to 5.5 lb). A large owl, presumed as an eagle-owl, recorded on the illegal wildlife trade from India purportedly weighed 3 kg (6.6 lb). The ear-tufts of the spot-bellied are very long and conspicuously of variable length, giving them a somewhat scraggly appearance at the tips. The ear-tufts of the spot-bellied eagle-owl measure up to 63 to 76 mm (2.5 to 3.0 in) in length. Most eagle-owls are well-feathered on both their leg and toes, while the barred eagle-owl is featherless on the toes and feathered on the legs, and the spot-bellied eagle-owl has feathered legs and feet, but the terminal digits of the toes are bare before the talons. The feet and talons as formidable as any eagle-owl, being very large, heavy and powerful for their size. Among standard measurements, this species typically measures 425 to 477 mm (16.7 to 18.8 in) in wing chord length, 230 to 250 mm (9.1 to 9.8 in) in tail length, 60 to 62 mm (2.4 to 2.4 in) in tarsal length and 52 to 54 mm (2.0 to 2.1 in) in culmen length. The subspecies of spot-bellied eagle-owl found on Sri Lanka, B. n. blighi, is linearly about 10% smaller than the birds found further north in India but about the same size as owls from the southern tip of India. B. n. blighi has a wing chord length of 370 to 455 mm (14.6 to 17.9 in), a tail length of 184 to 240 mm (7.2 to 9.4 in), a longer tarsus than northern birds at 63 to 68 mm (2.5 to 2.7 in) and a culmen length of 43 to 48 mm (1.7 to 1.9 in). One bird from Sri Lanka had a middle talon of 44.2 mm (1.74 in), a toe length of 50.6 mm (1.99 in) and a wingspan of 143 cm (56 in). The reported talon length above is very large relative to the size of this owl, the Eurasian eagle-owls found in Spain (Bubo bubo hispanus), although relatively small compared to other Eurasian eagle-owl races, were shown to have smaller talon lengths than the Sri Lankan spot-bellied eagle-owl. Other than size, the only feature that distinguishes northern birds from Sri Lankan birds is that northern birds possess an ill-defined band of honey-brown colour on the pectorals. The spot-bellied eagle-owl is overall a stark, grayish brown bird, with dark, coarse brown coloration over the back and upper wings. The throat and underparts are mainly pale fulvous in color with black and white horizontal stripes along the flanks of the body that become broad spots on the abdomen and under tail coverts. On the wings, the primaries are dark brown with lighter brown stripes and the secondaries are more heavily barred with buff-brown coloration. The lores are covered in bristly feathers and the cheeks are brownish-white with black feather shafts. The large ear tufts slant off to the sides. Juveniles birds are distinct from adult birds, being a much paler grayish-cream overall with fairly heavy brownish barring. Distinguishing the spot-bellied eagle-owl is relatively straightforward, since other Indian and southeast Asian eagle owls do not generally dwell in deep forests as does this species. The spot-bellied is the largest of the owls in its range other than the tawny fish owl (Bubo flavipes), which is restricted in both habitat and diet to mountain streams. The brown fish owl (Bubo zeylonensis), which is quite different in colouring if seen reasonably well, is slightly smaller linearly than the spot-bellied eagle owl and is found in more wetland-based (and often somewhat more degraded) habitats. The subspecies of Eurasian eagle-owl (Bubo bubo hemachalana) found in the Himalayas may inhabit higher elevations of the same mountains where the spot-bellied eagle-owl dwells in the lower elevations in the forested foothills but there their ranges barely abut. The Indian eagle-owl (Bubo bengalensis) (typically found in wooded vicinities of rocky areas) is around 10% smaller than the spot-bellied, the dusky eagle-owl (Bubo coromandus) (typically found in woods near wetlands) is around 15% smaller and the brown wood owl, the largest Strix widely found in the Indian subcontinent and Southeast Asia, is around 35% smaller. Furthermore, the colouring and markings of the spot-bellied eagle-owl is distinctive from all but the barred eagle-owl, which it does not co-exist within the wild. In both the barred and spot-bellied eagle-owls, they are immediately distinctive in the field from other eagle-owls by their pale-looking, sideways slanting ear-tufts, the degree of feathering on the legs and feet. The species pair unlike sympatric eagle-owls has the horizontal rather than vertical underside markings (which congeal somewhat in the barred to barring but appear as almost continuous spotting on the spot-bellied) over a much paler ground colour while the back is slightly grayer looking, lacking any warmer brown or tawny tones.