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Spot-bellied Eagle-owl - Bubo nipalensis
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Spot-bellied Eagle-owl - Bubo nipalensis

[Image: 350px-Spot-bellied_Eagle-Owl_by_N.A._Nazeer.jpg]

Scientific classification 
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Strigiformes
Family: Strigidae
Genus: Bubo 
Species: B. nipalensis

Description: 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.

[Image: Flickr_-_Rainbirder_-_Spot-bellied_Eagle...sis%29.jpg]

Distribution and habitat: This species is distributed the Lower Himalayas from Kumaon east to Burma, thence to central Laos and central Vietnam. They are found throughout the Indian subcontinent and peninsular Southeast Asia down into the southernmost limits of the range in Sri Lanka and to 12 degrees north in southern Thailand. The spot-bellied eagle-owl dwells mainly in primary or older second growth forests. Potentially, they can come to inhabit nearly all varieties of land-based habitats but prefer those such as dense, evergreen forests or moist deciduous forests within its range, though can range secondarily into tropical valleys, terrai and shola in the lower hills of India. Although often considered uncommon to somewhat rare, recent photographic evidence indicates that they are particularly widely found in different parts of India and may simply avoid detection, so long as appropriate wooded habitat remains. They are found in a range of climates from the temperate woodlands of Nepal to the humid, tropical rainforest of Southeast Asia. However. the spot-bellied eagle-owl is mainly a species of tropical and subtropical foothills, mainly being distributed at elevations of 900–1,200 m (3,000–3,900 ft), though have been found at anywhere from sea-level to 6,300 m (20,700 ft), the latter in the Transhimalayas.

Diet: This is a very powerful and bold predatory owl, which is assuredly at the top of the avian food chain in its forested range. However, no extensive study of its dietary habits is known. Even in larger eagle-owls such as the Eurasian eagle-owl, although they can and do prey on a wide range of prey including impressively large prey, most of the diet consists of small mammals, often small rodents such as voles and rats. There is no reason to assume that the spot-bellied eagle-owl does not also take a very large quantity of relatively small prey such as rodents until complete dietary studies are known. However, almost all of the prey thus far reported for this species is very large and impressive, much of it being presumably as heavy or heavier than the eagle-owls themselves. Due to being most widely reported as being chased and eaten by spot-bellied eagle-owls has led some authors to list their primary prey as pheasants. Among these, junglefowl (Gallus sp.) and kalij pheasants (Lophura leucomelanos), both weighing from 500 to 1,500 g (1.1 to 3.3 lb), are commonly eaten, as well as Indian Peafowl (Pavo cristatus), which can weigh anything from 2.75 to 6 kg (6.1 to 13.2 lb). The spot-bellied eagle-owl pounces on gamebirds while they're asleep on their perches in trees or bamboo clumps, often killing them in seconds with their powerful talons. Cases, where they've followed peafowl to their roosts and then pulled them out at sundown, have been reported. It also consumes an array of mammals, from small rodents to large prey such as apparent adults of Golden Jackals (Canis aureus), hares (Lepus ssp.), Large Indian Civets (Viverra zibetha), Indian spotted chevrotains (Moschiola indica), and even young muntjacs (Muntiacus sp.). These larger mammals are likely as much as 2 to 9 kg (4.4 to 19.8 lb) or even more. While most reported prey appear to be largely terrestrial, they are known to capture arboreal prey including Indian giant squirrel (Ratufa indica) and juvenile purple-faced langur (Trachypithecus vetulus). Additionally, they are considered a potential threat to toque monkeys (Macaca sinica), and one apparently caught an Indian flying fox (Pteropus giganteus) from its tree roost. Due to the capture of diurnal prey such as giant squirrel, partial daytime foraging habits have been inferred for the spot-bellied eagle owl. They will also opportunistically prey upon snakes, lizards (including large monitor lizards) and fish. Like several of the eagle-owls and fish owls but unlike most owls, the spot-bellied eagle-owl has been recorded as feeding on carrion. Thus far, they've been seen feeding on the carcases of goats (Capra aegagrus hircus) and Tigers (Panthera tigris).

[Image: 640px-Spot_bellied_Eagle_Owl.jpg]

Breeding: This species' nesting season is from December to March, however, an egg has been recorded as late as June in Cachar. Most nesting sites are in large, spacious tree hollows. Alternately, they use abandoned stick nests made by other large birds, in many cases those previously built by eagles, vultures or kites. They've additionally been recorded as nesting in caves and sheltered fissures of rock walls. In this species, only one egg has ever been recorded per clutch and this is only one of three amongst all owl species (besides the buffy fish owl (Bubo flavipes) and the barred eagle-owl) where this is known to be the case. The egg is white and round ovoid shape with a smooth surface, averaging 61.2 mm × 49.9 mm (2.41 in × 1.96 in) in size and are thus around the same size as the eggs of the largest living owls, the Eurasian eagle-owl and Blakiston's Fish Owl (Bubo blakistoni). It has been reported that both sexes engage in incubation but this may not be the case (male owls generally do little to no incubating in eagle-owls), with the male more likely temporarily covering the eggs while the female flies off for a short period. Few further details are known of their breeding biology, including the brooding and fledging stages due to this species reportedly being very fierce and aggressive in defence of their nests. Anecdotes have claimed that some rather serious injuries have been incurred in the process of approaching spot-bellied eagle-owl nests, thus caution and distance from active nests is recommended.

[Image: SpotbelliedEagleOwl.jpg]
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  • Claudiu Constantin Nicolaescu
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#2
Predation by Forest Eagle-Owl Bubo nipalensis on Mouse Deer Moschiola meminna.

An incident of predation on Indian chevrotain or mouse deer Moschiola meminna (Artiodactyla: Tragulidae) by a
Forest Eagle-Owl was observed in Puduthottam, a rain forest fragment (1,090m a.s.l.) approximately 90ha in size, bordering Valparai town (Coimbatore district, Tamil Nadu) in the Anamalai Hills (Western Ghats). Walking up a narrow path into a clearing by a stream-bed between 13:00 and 14:00hrs, my field assistant and I flushed a
Forest Eagle-Owl from the ground to our left. It had a small animal in its talons that it dropped as it flew across the stream ahead of us. On closer inspection, we saw it was a freshly killed young mouse deer, whose body was still warm. Its head had been completely torn off and was missing and the first few drops of blood began to flow as it lay on the ground.
Mammals form an important component of the diet of other eagle-owls in different parts of the world (Serrano 2000). Eagle-owls are also opportunistic feeders, taking birds and mammals weighing up to 1.5kg (Frikke
and Tofft 1997*). Predation studies have also examined differential predation by owls, and it was observed that owls preferred juveniles and sub-adult individuals, and
that they killed more often in open areas than in closed areas (Vaseallo et al. 1994, Rohner and Krebs 1996).




Spot-bellied Eagle-Owl Bubo nipalensis feeding on  Indian Flying Fox Pteropus giganteus.

Garjia Village (29.47°N, 79.15°E; 437m asl) is located on the banks of River Kosi, on the eastern boundary of Corbett Tiger Reserve (Uttarakhand, India). The village is surrounded by mature moist, mixed, and semi-deciduous forests, dominated by sal Shoria robusta on its western side, and a narrow stretch of river valley on its eastern, with similar mature forest habitat on 
the opposite bank of the river. On 12 January 2018 at c. 1720 hrs, Naveen Chardra Singh (verbal comm.) informed MN about a large owl being seen in a tree by the side of the road at Garjia. MN photographed the owl at c. 1730 hrs [39, 40]. It was holding a dead Indian flying fox Pteropus giganteus in its talons, and 
was feeding on it. The owl was identified as Spot-bellied Eagle Owl, based on such features as: large size, large black-and-white horizontal ear-tufts, large yellow beak, fully feathered tarsii, and prominent spotting on the underparts.
As per del Hoyo et al. (1999), bats are incidental prey items for many owls but, except for one species, owls do not specialise in preying upon bats. We could not locate any previous records of the Spot-bellied Eagle Owl feeding on bats, and hence this note.

[Image: 1bgw0rc.png]

[Image: bnlKgox.png]
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