Page:Popular Science Monthly Volume 6.djvu/501

Rh and the character of its nest. In the first place, as the male bird is much brighter in the color of its plumage, would it not require a concealing nest if it assisted in incubation? Now, does the male bird assist in covering the eggs? It unquestionably does.

Secondly, if the bird-concealing nest, a "pendulous and nearly cylindrical pouch," as described by Dr. Brewer, is constructed solely with reference to the protection of the parent-birds, would it not be within the range of probabilities that, the danger no longer existing, the labor of constructing so elaborate a nest would be abandoned. Has this actually occurred? During the summer of 1872, I found nine nests of the Baltimore oriole within a comparatively small area; in 1873, I succeeded in finding seventeen nests in an area nearly ten times in extent; and during the present summer (1874) I found thirteen nests in an area of the same extent as that examined in 1873. These thirty-nine nests I classified as follows: Of the nine nests of 1872 that I examined, six were so constructed as to effectually conceal the sitting bird, and three were sufficiently open at the top to give a hawk, hovering above it, a view of the bird.

Of the seventeen nests of the oriole which I found and inspected during the summer of 1873, eleven of them were "bird-concealing" in their shape, and the remaining six like the three I found in 1872, i. e., open at top.

During the present summer, Baltimore orioles have been unusually abundant, and, of the thirteen nests I found, eight were open at the top, and five were long, pendulous pouches, that wholly hid from view the sitting-bird.

Bearing in mind the supposed reason for building a nest that would conceal the parent birds when occupying it, I noted down the exact location of each of these thirty-nine nests. In every instance those nests that concealed the sitting bird were at a considerable distance from any house, in uncultivated parts, the larger number on an unfrequented island, the others on elm-trees growing on the banks of a lonely creek. In both of these localities, sparrow-hawks (Tinnunculus sparverius) were frequently seen—they are nowhere so numerous as some seventy years ago—as compared with the neighborhoods selected for the building of the open-topped nests, all of which were in willow and elm trees in the yards of farm-houses, and in full view of the people continually passing to and fro beneath them. The conclusion drawn from the study of these nests was, that the orioles, knowing there was much less (if not total) absence of danger from hawks, therefore constructed a less elaborate nest—one which answers every purpose of incubation, and yet does not conceal them when occupying it.

Of the nests that did conceal the sitting bird, every one was really open at the top, and the bird entered from above. The weight of the. bird, when in the nest, appeared to draw the edges of the rim together sufficiently to shut out all view of the occupant. The rims of