244 The Naturalist in La Plata,
size, and in other respects. Some have a spiral passage-way leading from the entrance to the nest cavity, and the cavity is in many cases only large enough to accommodate the bird; but in the gigantic structure of Homorus gutturalis it is so large that, if the upper half of the nest or dome were removed, a condor could comfortably hatch her eggs and rear her young in it. This nest is spherical. The allied Homorus lophotis builds a nest equally large, but with a small cavity for the eggs inside, and outwardly resembling a gigantic powder-flask, lying horizontally among the lower branches of a spreading tree. Pracellodomtis sibila-trix, a bird in size like the English house sparrow, also makes a huge nest, and places it on the twigs at the terminal end of a horizontal branch from twelve to fifteen feet above the ground; but when finished, the weight of the structure bears down the branch-end to within one or two feet of the surface. Mr. Barrows, who describes this nest, says: "When other branches of the same tree are similarly loaded, and other trees close at hand bear the same kind of fruit, the result is very picturesque." Synallaxis phryganophila makes a stick nest about a foot in depth, and from the top a tubular passage, formed of slender twigs interlaced, runs down the entire length of the nest, like a rain-pipe on the wall of a house, and then becoming external slopes upward, ending at a distance of two to three feet from the nest. Throughout South America there are several varieties of these fruit-and-stem or watering-pot shaped nests; they are not, however, all built by birds of one genus, while in the genus
The Woodhewer Family. 245
Synallaxis many species have no tubular passageways attached to their nests. One species--erythro thorax--in Yucatan, makes so large a nest of sticks, that the natives do not believe that so small a bird can be the builder. They say that when the tzapatan begins to sing, all the birds in the forest repair to it, each one carrying a stick to add to the structure; only one, a tyrant-bird, brings two sticks, one for itself and one for the urubú or vulture, that bird being considered too large, heavy, and ignorant of architecture to assist personally in the work.
In the southern part of South America, where scattered thorn trees grow on a dry soil, these big nests are most abundant. "There are plains," Mr. Barrows writes, "within two miles of the centre of this town (Concepcion, Argentine Republic), where I have stood and counted, from one point within a radius of twenty rods, over two hundred of these curious nests, varying in size from that of a small pumpkin to more than the volume of a barrel. Often a single tree will contain half a dozen nests or more; and, not unfrequently, the nests of several different species are seen crowding each other out of shape on the same bush or tree."
It would be a mistake to think that the widely different nesting habits I have mentioned are found in different genera. I have just spoken of the big stick nests, with or without passage-ways, of the Synallaxes, yet the nest of one member of this group is simply a small straight tube of woven grass, the aperture only large enough to admit the finger, and open at both ends, so that the
246 The Naturalist in La Plata.
bird can pass in and out without turning round. Another species scoops a circular hollow in the soil, and builds over it a dome of fine woven grass. It should be mentioned that the nesting habits of only about fifteen out of the sixty-five species comprised in this genus are known to us. In the genus Furnarius the oven-shaped clay structure is known to be made by three species; a fourth builds a nest of sticks in a tree; a fifth burrows in the side of a bank, like a kingfisher.