secured by means of a gable roof; and a half-inch hole immediately under the roof affords ventilation.
The bluebird covers the floor of her house with grasses to the depth of about an inch and a half. Away back against the rear wall she makes the little hollow in which she lays her eggs. I make her entrance one inch and a half in diameter, and just below the middle front. While brooding she can look outside, and this affords her some diversion during that monotonous task. This certainly seemed to be what one bluebird aimed at who nested in Mrs. Daily's wren house. The wad of grasses in that house reached clear up to the entrance, which was about four inches above the floor. Apparently this bird had tried to build her nest high enough so she could look outside.
Wrens always make a litter several inches high of twigs and other materials. In this litter they embed their nest of fine grasses and feathers. Hence I conclude that they want their entrance several inches above the floor, so that, on going in, they can walk over the litter and do not have to grope through it. Being small birds they need only a small house. After years of experimenting I have settled on five inches by seven for wrens also, but their house is so shaped as to afford height. The sides run up at the back to twelve inches. A half-inch hole high on each side affords ventilation. I make the entrance one inch and an eighth in diameter, just too small
