ALL the Hawks included under this heading are remarkable for their long legs, in which the tibial bone and the tarsus are about equal in length. In all the other Hawks, Eagles, Kites, Buzzards, and Falcons, the tibia is always longer than the tarsus.
The Long-legged Hawks are not such powerful birds of prey as the Eagles or Falcons, and do not possess, as a rule, the same dash and courage in pursuing their quarry, many of them feeding on a low kind of diet, and being robbers of eggs and destroyers of young birds. The birds of prey belonging to this sub-family are—1. The Gymnogenes; 2. The Harriers; 3. The Goshawks; 4. The Sparrow-Hawks.
THE BANDED GYMNOGENE[173] (Polyboroides[174] typicus).
From its general appearance, especially in its naked yellow face, this remarkable Hawk is considered to be a close ally of the Secretary Bird; but the proportions of its legs and its habits proclaim it to be nearly related to the Harriers. Two kinds of Gymnogenes are known, one inhabiting Africa, and the other being found in Madagascar. The food of the present species appears to consist of Frogs and Lizards, and at times it walks over the ground which has been recently burnt, in pursuit of insects and small reptiles; at other times it will sit for a long time on stumps by pools of water, watching for Frogs, which in such situations form its favourite food. The Gymnogenes are remarkable in the class of birds for being able to put their leg “out of joint” at will (that is to say, they can bend the tarsus backwards just as they please); and this is a fact which may be accepted as a certainty, since its truth has been tested by many trusty and independent observers. One of these, the late M. Jules Verreaux, states that the tarsi are movable at the “knee”-joint toward the front from behind, a provision which, from the facility it affords the bird for drawing up Frogs out of the marsh-holes by means of its talons, is of no little service to it. The exceedingly compressed toes of this species also enable it to introduce its long tarsi into the narrow crevices of the rocks. He saw it twist and turn its legs in all directions in capturing its prey in marshy places. Mr. Thomas Ayres also says that “the legs of this bird bend backward at the knee in an extraordinary manner, very much as if they were out of joint.”
The Banded Gymnogene is nearly twenty-four inches in length, and is of a light grey colour, with black wings, the secondaries being grey like the back, with a black band before the tip; the lower back is white barred with black; the tail black with a white tip and a white bar across the middle; the throat and chest are grey like the back, and the rest of the under surface is white barred with black. The cere and bare space round the eye are yellow when the bird is alive.
THE HARRIERS (Circus).
All the Harriers have a facial disc as in the Owls, though not so distinct as in the latter group of birds. In both, however, the disc is formed by a ruff of soft, close-set plumes, which encircle the face; and hence in most classifications the Harriers have been considered as being closely allied to the Owls, on account of their having this “facial disc.” Their structure and habits, however, entirely do away with the idea of there being any real affinity between these two groups of accipitrine birds.
Before the draining of the fens in England, Harriers were by no means uncommon in certain localities; but they are becoming rarer year by year, as each favourite haunt passes from them under the dominion of the agriculturist. Three kinds were found in England, of which the Hen Harrier (Circus cyaneus) was the rarest; Montagu’s Harrier (C. pygargus) was the most plentiful and the most widely distributed; and the Marsh Harrier, or Moor Buzzard (C. æruginosus), the most powerful. This is the species which has held its own best, as it is still found breeding in some few places in the United Kingdom. The habits of all the Harriers are very similar, and the genus Circus is probably—with the exception of the Peregrine Falcons—the most universally distributed of any Raptorial birds, for there is scarcely any part of the world where a Harrier is not found.
THE MARSH HARRIER (Circus æruginosus).