464 ANIMAL LIFE-HISTORIES 



burrows often four to five feet deep, and terminating in a round 

 chamber. Others build a massive oven-shaped structure of clay 

 on a branch or other elevated site. Many of those that creep 

 on trees nest in holes in the wood. The marsh-frequenting 

 kinds attach spherical or oval domed nests to the reeds; and 

 in some cases woven grass and clay are so ingeniously combined 

 that the structure, while light as a basket, is perfectly impervious 

 to the wet and practically indestructible. The most curious nests, 

 however, are the large stick structures on trees and bushes, in 

 the building and repairing of which the birds are in many cases 

 employed more or less constantly all the year round. These 

 stick nests vary greatly in form, 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 Homoias 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. The nest is spherical. 

 The allied Ho-jnoris 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. Pracellodomus sibilatrix, 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. . . . Synallaxis phi-yganophila 

 makes a stick nest about a foot in depth, and from the top a 

 tubular passage, formed of slender twigs intertwined, runs down 

 the entire length of the nest, like a rain-pipe on the wall of a 

 house, and then becoming external, slopes upwards, ending at 

 a distance of two to three feet from the nest." It must not be 

 supposed that in this family the species of the same genus 

 necessarily build in the same way. For example the Oven- 

 Birds {FiLrnarius) are so named on account of the shape of the 

 clay nests constructed by three species, but another species makes 

 a stick nest, and still another lays its eggs in a burrow. 



A nest having been constructed, both parents take part in 

 the care of eggs and young. Probably in the majority of cases 

 incubation is entirely or mostly performed by the mother, though 



