In the Himalayas, where the species is also tolerably plentiful, its habits vary somewhat, and it not unfrequently comes close to habitations for offal or bones, and behaves in a very Vulturine manner. Captain Hutton writes:—“Marvellous, indeed, are the stories told, both by natives and Europeans, of the destructive habits of this bird, and both accounts, I fully believe, have scarcely a grain of truth in them: all I can positively say on the point, however, is that I have known the bird well in its native haunts for thirty years and more, and never once, in all that time, have I seen it stoop to anything but a dead carcase. As to carrying off hens, dogs, lambs, or children, I say the feat would be utterly impossible, for the creature does not possess the strongly-curved, sharp-pointed claws of the Eagle, but the far straighter and perfectly blunt talons of the Vulture. Day after day I have seen them sweeping by along the face of the hill, like the wandering Albatross at sea, and, like it, ever in search of offal, which, when found, is not swept off the ground after the manner of the Kite, but the bird alights upon it, as it would upon a Bullock, and then, if the morsel is worth having, devours it on the spot, and again launches itself upon its wide-spread wings and sails away as before. There is no sudden stooping upon a living prey, as with the Falcon tribe, but its habits and manners in this respect are, as far as I have seen, entirely Vulturine.”
The Lämmergeier measures about three feet and a half in length, and its outspread wings often extend to as much as nine feet in expanse. A second species is found in Africa, the Southern Lämmergeier (Gypaëtus ossifragus), which differs from the European one, in having the tarsus bare, instead of being feathered to the toes.
THE TRUE EAGLES (Aquila).
In Australia no true Eagle is found, but a very powerful bird called the WEDGE-TAILED EAGLE (Uroaëtus[184] audax[185]) inhabits that country, differing from all its more northern relations in its very long and wedge-shaped tail, which is like that of the Lämmergeier.
The true Eagles have a very powerful bill, with a festoon distinctly marked in the edge of the upper mandible, which is, however, different from the toothed bill of the Falcons, to be considered presently. They nearly all possess a large bony shelf over the eye, which may serve to protect that organ from the sunlight during some of the aerial excursions the bird makes.
EYE OF EAGLE, SHOWING CRYSTALLINE LENS. (After Yarrell.)
The orb of the eye in the Eagles is supported by a ring of bony plates, numbering fifteen in the Golden Eagle. These bony plates are capable of slight motion upon each other. The figure represents the crystalline lens of the same bird, the lens being subject to great variety of form in different birds. In the Eagle the proportion of the axis to the diameter of the lens is as 3810 to 5710; in the Eagle Owl, which seeks its prey at twilight, the relative proportions of the lens are as 6710, to 7810; and in the Swan, which has to select its food under water, the proportions of the lens are as 3 to 3810. Birds have also the power of altering the degree of the convexity of the cornea. With numerous modifications of form, aided by delicate muscular arrangement, birds appear to have the power of obtaining such variable degrees of extent or intensity of vision as are most in accordance with their peculiar habits and necessities.[186]
In these birds is found a return of that difference in the size of the sexes which was so noticeable in the Sparrow-Hawks, for in the Eagles the female is decidedly larger than the male. There are two convenient groups into which the Eagles may be divided, according as they have feathered or unfeathered legs. All the true Eagles belong to the first section, all the less noble and Serpent-eating kinds to the latter section. Although they are birds of grand physique, it is a question whether Eagles deserve the position they enjoy for nobility of disposition: they are rapacious it is true, but not always brave, for one Golden Eagle will give way to a Peregrine Falcon, while the grand-looking IMPERIAL EAGLE (Aquila heliaca, see figure on p. 235) is said by a good observer in India, Mr. A. O. Hume, C.B., to be no better than a great hulking Kite. He adds:—“Much has been written about the daring and fierceness of this Eagle. I can only say that in India (where possibly the climate is subversive of courage), I have never seen the slightest indications of these qualities. I have driven the female off hard-set eggs, and plundered the nest before the eyes of the pair, without either of them flapping a pinion even to defend what a little Shrike will swoop at once to save; and I have seen a couple of Crows thrash one of them soundly. As a rule, this species with us is an ignoble feeder. I have generally found them gorged with carrion, and after a good meal they will sit stupidly on a tree, or any little mud pillar, and permit you to walk within thirty yards of them; but before feeding they are somewhat wary, and can by no means always be secured, even when seen sitting. On more than one occasion I have seen Desert Rats (Gerbillus erythrurus) in their crops, and I once shot one of a pair which were busy, on the line of rail at Etawah, devouring a Bandicoot Rat (Mus bandicota), which some passing train had cut in two. Occasionally, but rarely, I found that they had eaten Quails and other birds. Once I shot a male which was dancing about on the ground in such an astounding fashion that I killed it to see what the matter was. The bird proved to have been choking. It had swallowed a whole dry shin-bone and foot of an Antelope. The bone apparently could not be got down altogether, and in trying to void it, the sharp points of the hoof had stuck into the back of the roof of the mouth.”[187]
THE GOLDEN EAGLE (Aquila chrysaëtus[188]).