Hieraetus Kaup, Mus. Senckenb., iii, p. 260 (1845).
Type, Falco pennatus Gmelin.
The genus Hieraetus contains the birds termed Hawk-Eagles. They differ from the true Eagles in their generally more slender proportions, shown especially in their smaller bills and longer and more slender tarsi; the tail is longer in proportion than it is in the Eagles, whilst in most of the Hawk-Eagles there is a phase of plumage in which the underparts are partly or wholly white. The emarginations to the primaries are generally much deeper than they are in the birds of the genus Aquila.
In Hieraetus the bill is moderately strong, much hooked and with a prominent festoon to the upper mandible ; the nostrils are elliptical and oblique; the wing is long, the fourth primary longest and exceeding the secondaries by more than the length of the tarsus; tail nearly square and equal to more than half the wing in length; tarsi feathered to the toes; toes long, outer toe rather longer than the inner; claws sharp and well curved; inner and hind claw both large, the latter the larger.
The genus is represented in Europe, Asia, Africa and Australia, two species occurring in India.
Key to Species.
A.Larger; wing over 480 mm............... H. fasciatus, p. 77.
B.Smaller; wing under 450 mm............... H. pennatus, p. 79.