Ornithological biography, Vol. 3 (of 5)

by John James Audubon

In the aquatic tribes numerous remarkable modifications are observed. Beginning with those which have the extremity of the toe largest and most rounded, we find that the Geese, Ducks, and Gulls, supply good examples. Thus in Larus marinus, the protuberance beneath the claw is rounded, and covered with small rounded and flattened papillæ, of which there is a semicircular terminal series of a larger size, as is represented by fig. 1.

FIG. 1.

FIG. 2.

FIG. 3.

The Pelicans and Gannets are similar in this respect to the Gulls, as are the Cormorants, which, however, have the terminal pad projecting and more pointed. In the Guillemots, also, it is rounded, with small distinct rounded scales. In the Frigate Bird, in which the webs are short, and do not modify the pads, the terminal scales are similar to those of the Gulls. In the genus Lestris, they are smaller, and obscured by the webs, their papillæ smaller and more pointed. In the Terns, they are similar to those of the Gulls, but narrower, and with the papillæ large. In Phaeton æthereus, the webs appear to obliterate the terminal papillæ, which are very small. In all these, the extremities of the toes are more or less rounded, and terminated just beneath the claw by a semicircular series of scales larger than those immediately behind.

In the Auks, however, there is a large scale or plate, on the inner side of the middle toe, and then a series of narrow scales. In Mormon glacialis, of which the end of the middle toe is represented by fig. 2, there is a single much recurved narrow horny plate, behind which is a narrow series of oblong scales. In the genus Puffinus, there is also a single short rounded terminal scale or plate.

The Colymbi or Divers have the end of the toe very narrow and flat, with a single small rounded terminal plate, and numerous small scales behind it. These birds have the claws depressed, a form which shews its extreme development in the Grebes. Of the extremity of the middle toe of one of these, Podiceps cristatus, fig. 3. is a representation. Here the claw is almost quite flat, and the end of the toe beneath it is not elevated or rounded as in almost all the other genera, but perfectly depressed, and having its outline concave, but still, as usual, with a series of large scales.