The mountain hawk-eagle (Nisaetus nipalensis) or Hodgson's hawk-eagle, is a large bird of prey native to Asia. The latter name is in reference to the naturalist, Brian Houghton Hodgson, who described the species after collecting one himself in the Himalayas. A less widely recognized common English name is the feather-toed eagle. Like all eagles, it is in the family Accipitridae. Its feathered tarsus marks this species as a member of the subfamily Aquilinae. It is a confirmed breeding species in the northern part of the Indian subcontinent, from India, Nepal (hence the epithet nipalensis) through Bangladesh to Thailand, Taiwan and Japan, although its distribution could be wider still as breeding species. Like other Asian hawk-eagles, this species was earlier treated under the genera of Spizaetus but genetic studies have shown this group to be paraphyletic, resulting in the Old World members being placed in Nisaetus (Hodgson, 1836) and separated from the New World species. As is typical of hawk-eagles, the mountain hawk-eagle is a forest dwelling opportunistic predator who readily varies its prey selection between birds, mammals and reptiles along with other vertebrates. Although classified currently as a least-concern species due its persistence over a rather wide distribution, this species is often quite rare and scarce and seems to be decreasing, especially in response to large-scale habitat degradation and deforestation.
BEHAVIOUR IN THE WILD
The Mountain Hawk-Eagle feeds on small to medium-sized preys including mammals (hare, marten, flying squirrel, squirrel and shrew moles), birds (pheasants, jays and others) and reptiles such as snakes and lizards. But the diet varies according to the region, and the eagle takes the most abundant preys available in the habitat. The Mountain Hawk-Eagle hunts mainly in forests and forest edges. It hunts from perch, waiting for prey, or searching while moving from perch to perch. It may also fly above the canopy while looking for animals. They are monogamous and the pair has long-term pair-bonds. They often stay in their home range all year round. However, outside the breeding season, they live separately. The courtship displays usually start in autumn with aerial displays. The birds perform undulating and parallel flights together, and other acrobatic figures including approaching stoops. The nest-building starts while the courtship displays are underway. They nest in large trees on mountainsides. The area is defended and both mates chase out intruders. The Mountain Hawk-Eagle is sedentary in its range, although some dispersion, probably by juveniles, is reported. It soars with the wings held slightly forwards and above the body in shallow V, but it glides with the wings at body-level. The flight is agile and powerful during the displays.
REPRODUCTION OF THIS SPECIES
The breeding season varies according to the range, and occurs between December and March in Sri Lanka, from January to April in Japan, and between February and June in the Himalayas. Both mates build a large nest with thick dead branches for the base, and thinner sticks for the upper structure. The cup is lined with twigs and green leaves. It is placed in a large tree on lateral branches. The female lays a single white egg and incubates during 43-50 days. The male provides her food during this period and later, the female feeds the chick with the preys brought at nest by the male. The young eagle fledges about 70-80 days after hatching. However, it returns regularly to the nest to be fed and the dependency period may be long.
PROTECTION / THREATS / STATUS
The Mountain Hawk-Eagle is scarce to uncommon throughout the range. The species is threatened by extensive deforestation and replacement of many broad-leaved forests by monocultural plantations of conifers, especially in Japan. For these reasons, the population is in decline, but has not been quantified. However, the Mountain Hawk-Eagle is currently evaluated as Least Concern.