Birds and Birding's Guide to:

Watching THE PLOVER-LIKE BIRDS

THE GULLS AND THEIR ALLIES

The Skimmers

(Subfamily Rkynchopince).—The Skimmers, known also as Scissors-bills, Razor-bills, or Shearwaters (not the true Shearwaters, however), while quite Tern-like in many respects, differ from them, as indeed they do from all other birds, by the peculiar modification of the bill, this being long, laterally much compressed, and with the lower mandible no thicker than a knife-blade.

The lower mandible is also much longer than the upper one, which is itself freely movable, the bill throughout being an obvious adaptation for securing their food, which consists of small fish, shrimps, etc. They do not dive for their food as do the Terns, nor do they pick it up while swimming, for they rarely sit upon the water; but they obtain it by skimming rapidly over the surface with the lower mandible dipped into and cleaving the. surface, thus scooping it up much after the manner of whales. The thinning of the lower mandible is clearly for the purpose of reducing the friction in passing through the water, while the upper one is shortened and has become movable to keep it out of the way.

As regards their other characters, the Skimmers are birds of medium size, exhibiting a length of between sixteen and twenty inches, with very long, slender wings, a short and slightly forked tail, and very small feet in which the webs are deeply indented between the middle and inner toes.

The plumage is pure white below and black with more or less white-tipping to certain of the feathers above. In flying, the body is carried at an angle instead of horizontally, as in most birds, in order that the wings may clear the water as they skim over its surface. Most of the feeding is done in the morning and at dusk, or possibly in the night, the birds mainly resting during the middle of the day. Darwin observed the Black Skimmers in South America busily engaged in feeding in a shallow lake which was teeming with small, fish.

He states that”they kept their bills wide open, with the lower mandible half buried in the water.

Thus skimming the surface, they plowed it in their course; the water was quite smooth, and it formed a most curious spectacle to behold a flock, each bird leaving its narrow wake in the mirror-like surface. In their flight, they frequently twist about with extreme rapidity, and so dexterously manage, that with their projecting lower mandible they plow up small fish, which are secured b\ the upper half of their scissor-like bill."

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