488 



hat medium. So also a bird which immediately finds 

 its food with the wings closed, or only with a partial 

 use of them, subordinate to that of the feet, as in the 

 birds which chase their prey under water, those that 

 perch upon flexible stems and twigs, and a few others, 

 is a ground bird. No matter whether it walks the 

 bare earth, the vegetable surface, the boles or branches 

 of trees, or perches, or climbs, or swims, or dives, if 

 aerial motion does not form part of the act of capture, 

 it is not an air bird. Many ground birds range far 

 on the wing in search of places where they may feed 

 or nestle ; but the distinction between that and feed- 

 ing on the wing, that is, arriving directly at the prey 

 from the air only, is obvious enough. If the bird 

 moves anew from any support but that of the air, 

 that element has, as it were, rendered it up ; and be 

 the support rock, earth, plant, or water, there is an 

 unbroken connexion with the ground. 



The distinction between omnivorous birds and 

 either of these divisions is not so clear. But this is 

 what might be expected : the air and the ground are 

 the extremes, and in comparing them we have the 

 advantage of the greatest contrast of which the class 

 admits. There are some birds which have both habits, 

 and they are chiefly miscellaneous feeders ; and, if we 

 had only two divisions, there are very many species 

 which would belong equally to both , to the observer 

 of the one habit they would be air birds, but they 

 would be ground birds to the observer of the other 

 habit. 



With the three divisions there would still be diffi- 

 culties on the confines, nor could we avoid similar 

 difficulties though we made three hundred divisions ; 

 for in nature there are no absolute divisions but those 

 of species, or perhaps individuals. Natural divisions 

 are, therefore, out of the question in this or in any 

 other department of natural history. But there is a 

 natural gradation, and that gradation we can approxi- 

 mate, and approximate the more nearly the better 

 that we understand the whole ; but completely to reach 

 it would require a degree of knowledge which man 

 in this world never can possess. 



The primary divisions in the arrangement which 

 has been hinted at would be as unnatural, as artificial 

 as those in any of the systems. But there would be 

 at least one great advantage, we should have the 

 whole bird presented to us in the general definition, 

 and not a mere bill, foot, or wing, as we have at 

 present. Thus we could, from a sort of general 

 enunciation, proceed equally to all the parts by 

 analysis, whereas, as matters stand at present, we 

 have to collect the knowledge of all the parts, in 

 perfect ignorance of the use which we are to make 

 of this knowledge, till we are in possession of the 

 whole. This is a very discouraging mode of going 

 to work ; and if we are compelled to stop short of the 

 whole, all the labour which we have taken is without 

 purpose and without profit; the subject remains un- 

 known, and the mind has not profited by the exertion. 

 But we must stop here ; some further observations will 

 be found in the article CLASSIFICATION. 



VI. FEET OF BIRDS. From the notice which has 

 been taken of the habits of the more remarkable birds 

 in the preceding observations on the structures and 

 uses of their bills, we shall be enabled to reduce this 

 and the following branch of the subject to little more 

 than mere catalogues; and all parts of the subject 

 would have the same brevity, if a system could be 

 formed as above suggested, free from all structural 



RD. 



; details ; because then we would have nothing to con- 

 sider along with any organ but its own immediate 



i function. 



The feet of birds are used in the air, on the earth, 

 on vegetable supports, and in the water. The only- 

 feet which are, strictly speaking, used in the air, are 

 used in the capture ot prey, or they are clutching feet, 

 the feet of all birds of prey, diurnal and nocturnal, 

 but the feet of no other birds. The typical foot of 

 these is the foot of the jer falcon. 



Jer Falcon. 



The character of this foot is to have four toes, all 

 free to their bases, and three turned to the front and 

 one to the rear, in the general habit ; but those species 

 which fish have the exterior front one reversible, so 

 that the toes act two against two, and thus lift the 

 prey more easily out of the water than if they had 

 the common position. When the toe is reversible it 

 is generally the largest in the foot, and the claws 

 upon these feet have their under sides smooth and 

 rounded as well as the upper ones ; whereas those 

 birds which use the feet only in killing, have the under 

 sides of the claws grooved, or with two cutting edges, 

 by which means they inflict much more lacerated and 

 mortal wounds. 



The claws of the more typical birds of prey (which 

 are the only ones which get the name of talons) are 

 used only in killing the prey, or in holding it while 

 depluming, skinning, or tearing asunder, by the beak ; 

 but the vultures and other less typical species which 

 eat carrion, and rarely kill living prey, use the claws 

 more for retaining their hold, while they stand on the 

 bodies of dead animals. 



Size is not so much an indication of power in these 

 feet as compactness and symmetry ; the tarsi of the 

 more powerful ones are all short; and in proportion 

 as the preying of the bird becomes what is called 

 more ignoble, the tarsi increase in length. Thus in 

 the secretary falcon (Serpentarius] of Africa, which 

 feeds much upon reptiles, and often upon poisonous 

 ones, the tarsi are as long as those of the wading 

 birds. This, however, is not to answer a wading pur- 

 pose, but to raise the body of the bird above the 

 reach of the envenomed prey, as this falcon (which, by 

 the way, is not a falcon) kills by the clutch or truss 

 of the talons, after the general habit of the order. 



As walking is not much a habit with birds having 

 this description of foot, the femur, or thigh bone, has 

 not a great deal of motion or of muscle. The largest 

 muscles are those which work the toes and claws, and 

 they are situated upon the tibia:. They are always 

 protected by a thick feathery covering, and in the 

 species which inhabit cold countries, the feathers are 

 continued on the tarsi, or they hang down and shel- 

 ter those parts of the feet, so that the tendons and 



