Description wikipedia

The Great Nicobar serpent eagle (Spilornis klossi), also known as the South Nicobar serpent eagle, is a species of bird of prey in the family Accipitridae. It is probably the smallest known eagle, with a weight of about 450 g (0.99 lb), a wingspan of 85 to 95 cm (33 to 37 in) and a body length of about 38 to 42 cm (15 to 17 in). It is endemic to forest on the Indian island of Great Nicobar. It is threatened by habitat loss. All major authorities now treat the Great Nicobar serpent eagle as a species, but in the past it was sometimes considered a subspecies of S. minimus. Today S. minimus is either considered a subspecies of the crested serpent eagle or a monotypic species from the central Nicobar Islands, the Central Nicobar serpent eagle. Overview The Great Nicobar serpent eagle (Spilornis klossi), also called the South Nicobar serpent eagle or Nicobar serpent eagle, is a small bird of prey in the family Accipitridae. It is restricted to the southern Nicobar Islands of India. This bird is one of the smallest species of eagles in the world, weighing about 450 g (0.99 lb), and has a wingspan of 85 to 95 cm (33–37 in) and a body length of 38 to 42 cm (15–17 in). S. klossi is closely tied to dense evergreen forested areas on Great Nicobar, Little Nicobar and nearby islands. This eagle species is threatened mainly by the loss and fragmentation of the evergreen forest, as well as large development projects planned for the area. Today, most authorities treat the Great Nicobar serpent eagle as a separate species. However, in the past, it was often placed within the Crested serpent eagle (Spilornis cheela) clade or under the name Spilornis minimus. Taxonomy and systematics The Great Nicobar serpent eagle belongs to the order Accipitriformes, family Accipitridae and genus Spilornis. It is a small forest-dwelling eagle endemic to the Nicobar Islands. This species was first observed by William Louis Abbott and described by Charles W. Richmond in 1902, who named it Spilornis klossi after C. B. Kloss.For much of the 20th century, different authors treated S. klossi in different ways. Some placed it as a subspecies of the crested serpent eagle (S. cheela minimus or S. cheela klossi), while others treated it as a separate species. Handbooks and checklists by various researchers, all used slightly different taxonomic arrangements, which is why older books often list “Small/Nicobar serpent eagle” under S. minimus rather than S. klossi. More recent works on Indian raptors and endemic birds have noted that the Great Nicobar serpent eagle is extremely small, with very plain, pale-brown underparts, and that it is confined to the southern Nicobars. Its isolated habitat location and morphological differences have led major ornithology lists, such as BirdLife International and Birds of the World, to treat S. klossi as a distinct island species. Other members of the genus include the Andaman serpent eagle (S. elgini) in the Andaman Islands and the Crested serpent eagle (S. cheela) found on Asian mainlands and larger islands. Description The Great Nicobar serpent eagle is one of the smallest described species of eagles. Adults are about 38 to 42 cm long, with a wingspan of 85–95 cm and weigh approximately 450 g. It looks noticeably smaller and more compact than the crested serpent eagle, with shorter wings, a shorter tail and underparts that are mostly plain, without heavy spots or bars. Males and females look similar, although females are slightly larger. The upper body is brownish with a slight coppery shine. Wing feathers have narrow pale tips, and the back and sides of the neck are a paler cream-brown. The underwing is mostly buff-brown, becoming paler towards the tip, with darker coverts that have clear pale edges. The top of the head is blackish with small pale tips, and the cheeks and sides of the face are grey. The throat is off-white with a faint grey line down the centre. The breast is warm buff-brown, fading towards a paler golden-orange on the belly, thighs and under the tail. The main flight feathers are dark brown to blackish towards the tips, sometimes with smaller white tips. Under the wing, parts closest to the body are paler and crossed by two darker bars. The tail is pale brown with a strong dark band near the tip and a fainter band towards the middle. The eyes, legs, cere, base of the bill, and bare skin on the face are bright yellow. The middle of the bill is bluish-grey and the tip is black. Juveniles look paler with more buff edging on the back, wings and head feathers. Their wing tips are whiter and usually have three dark tail bands instead of two compared to the adults. Their eyes are brownish-grey, and the yellow of the feet and cere can have a greenish tint. The call of Great Nicobar serpent eagle is a high-pitched, whistled note, often given singularly or in short series. Compared with crested serpent eagles, its calls are simpler and quieter. Distribution and habitat The Great Nicobar serpent eagle is endemic to the southern Nicobar Islands. It has been recorded on Great Nicobar, Little Nicobar, Menchal, and several small nearby islands such as Treisand Pilo Milo. Its population size is considered scarce across this small range, which covers less than 1,000 km². The species is strongly linked to evergreen rainforests. It occurs from near sea level up into low hills, mainly in mature forests with a closed canopy. It can also be found in nearby secondary forest and along forest edges, and sometimes near streams, clearings or meadows. It is most often seen perched quietly in the canopy or sub-canopy, or gliding above the trees. Most of its habitat lies within the Great Nicobar Biosphere Reserve (GNBR), which includes Campbell Bay National Park and Galathea National Park, and became part of UNESCO’s Man and the Biosphere network in 2013. Bird surveys and checklists from GNBR observe S. klossi, but at low numbers compared to other related birds of prey. These local lists also show that S. klossi occurs together with S. cheela on Great Nicobar. Behaviour and ecology General behaviour The Great Nicobar serpent eagle is mostly observed alone, but pairs are sometimes seen and thought to be monogamous, showing territorial behaviour. For much of the day, it perches in the canopy, watching for prey. Display flights are not reported, possibly due to their preferences in closed forests.