Size of Spot-Bellied Eagle-Owl
Spot-Bellied Eagle-Owl is a rather 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 is from 1.3 to 1.5 kg (2.9 to 3.3 lb) but this is probably towards the low end or is possibly representative only of smaller males.
Body Mass of Spot-Bellied Eagle-Owl
The body mass range of Spot-Bellied Eagle-Owl is similar to that of the larger race of Barred Eagle-Owl, which is 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). Other than size, the barred eagle-owl is similar in appearance to this species. Both the barred and spot-bellied eagle-owls are not greatly distinct from other eagle-owls other than their sideways slanting ear-tufts, which in 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 other eagle-owls are well-feathered on both their legs and toes.
Feet of Spot-Bellied Eagle-Owl
The feet and talons of Spot-Bellied Eagle-Owl are equally as formidable as any eagle-owl, being very large, heavy and powerful for their size.
Measurement of Spot-Bellied Eagle-Owl
Spot-Bellied Eagle-Owl 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.
Concentration of Spot-Bellied Eagle-Owl
Spot-bellied eagle-owl is found on Sri Lanka, and is linearly about 10% smaller than the birds found further north and eastern circle in India but about the same size as owls from the southern tip of India. B. N. blighti 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
Structure of Spot-Bellied Eagle-Owl
Spot-Bellied Eagle-Owl is overall a stark, greyish brown bird, with dark, coarse brown coloration over the back and upper wings. The throat and under parts are mainly pale fulvous in colour 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 greyish-cream overall with fairly heavy brownish barring. Distinguishing the spot-bellied eagle-owl is relatively straight forward, since other Indian and south-east 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.
Call of Spot-Bellied Eagle-Owl
Spot-Bellied Eagle-Owl is noted for its strange, human-sounding call, it was suggested that it be the cryptid known as ulama or "Devil Bird" in Sri Lanka. A local name is Maha Bakamuna ("large horned owl"). This call consists of a scream, which rises and then falls in tone. The territorial call of spot-bellied eagle-owl consists of low hoots, consistent with most eagle-owls, with two-second intervals between hoos. The voice is booming, deep and carries quite far.