Page:Natural History, Birds.djvu/185

172 loud discordant noise. They perforate the trunks of trees from the side, making a hollow in the wood, in which the nest is formed; and the female usually lays four eggs." The noise alluded to in the above description, produced by the flapping of their heavy wings in flight, combined with that occasioned by the clattering of their mandibles, is said to be so great as to inspire terror, when the cause is unknown; and to resemble those flaws of rough and sudden winds, which often rise so unexpectedly in tropical regions, and blow so violently. The larger species are extremely shy, and difficult of approach: like some of the Corvidæ, they usually perch on the leafless branches of the loftiest trees, when their vision, unimpeded by foliage, ranges over a wide extent.

The singular excrescences which in most of the species arise from the beak, sometimes equalling that organ, large as it is, in size, not only in different species vary much in form and size, but even in the same species at different stages of its life; indeed, in very young birds there is no trace of its existence. The perpendicular furrows which are seen on the sides of the upper mandible, are supposed by the Europeans resident in the Moluccas to be dependent on age, one being acquired every season; and hence they give the Hornbills the appellation of Jerar-vogel, or Year-birds. We have remarked on its lightness, owing to its cellular structure, permeated by air; but it is also observable that the bones of the body and limbs are more completely penetrated by this