Birds: Types of Feet or Claws in Birds
Types of Feet or Claws in Birds
The feet of birds are also modified variously in accordance with the character of the environment and the manner of locomotion. For illustration see figure 140.
1. Cursorial or running feet:
In running birds, the legs are powerful and the number of toes is reduced. Hind toe may be elevated, reduced or absent. In bustards, coursers and ratites such as emu, rhea and cassowary, only 3 toes directed forwards are present. Ostrich (Fig. 140 (0) has only 2 toes, of which the outer one is smaller and without a nail.
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2. Perching feet:
Majority of birds belong to the category of perching birds or such as finche [Fg 140 (3)), sparrows, [Fig. 140 (2)] crows, bulbuls, robins, mynahs, etc. Toes are anterior and slender, while one toe or hallux is posterior, strongly built and apposable, so that they can securely fasten the foot to a branch or a perch.
3. Scratching feet:
Feet of fows(fig. 140- 7 quails and pheasants, etc, are stout, with strongly developed claws and well adapted for running as well as scratching the earth. Foot of male bird is usually provided with a pointed bony spur of offence and defence.
4. Raptorial feet:
Predatory or carnivorous birds, such as eagles, kites, vultures and owls. [Fig. 140 (4)] etc. have strongly taloned feet for striking and grasping their prey. Toes have strongly developed, sharp and curved claws. Large and fleshy bulbs, called tylari, are found on the undersurface of the toes, especially developed in the sparrow-hawk. In osprey [Fig. 140 (5)] and Ketupa, tylari are absent but horny spines are present, which help in gripping slippery preys such as fish.
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5. Wading feet:
Legs and toes are exceptionally long and slender in wading or marshy birds such as herons, [Fig. 140 (11)] snipes, jacana, [Fig. 140 (6)] lapwing, etc. These serve to walk over aquatic vegetation or marshes. Web is absent or feebly developed.
6. Swimming feet:
In swimming birds, the toes are webbed, partially or completely. In diving birds, like coots [Fig. 140 (9)] and grebes, [Fig. 140 (10)] the web is lobate and the toes are free. In swimming and paddling birds, such as ducks [Fig. 140 (12)] and teals, avolet [Fig. 140 (8)] only the anterior 3 toes are united in a web. In pelican and cormorant [Fig. 140 (13)] all the 4 toes are enclosed in the web.
7. Climbing feet:
In parrots [Fig. 140 (17)] and woodpeckers [Fig. 140 (14)] the feet are used as grasping organs and especially adapted for climbing vertical surfaces. Second and third toes point in front, while the first and the fourth toes point backwards.
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8. Clinging feet:
In swifts, martinets [Fig. 140 (15)] kingfisher [Fig. 140 (16)] and humming birds, all the 4 toes point forwards and serve to cling to steep faces of cliffs or under caves of houses, etc.
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