The Chimney Swift 117 



inner vertical sides of hollow trees, but when the white man came, with his 

 chimneys, they left their homes and came to dwell with him. 



A chimney is usually occupied by but one pair of birds. It is only in the 

 autimin, when the Swifts accumulate from far and near about some favorite 

 roosting-place, that we see so many inhabiting one chimney. Their eggs are 

 four or five in number, and are white. Nature is not inclined to lavish her 

 coloring material on the shells of eggs where it is not needed. With a com- 

 paratively few exceptions, those which are deposited in dark places, as in chim- 

 neys, or holes in trees, or in the ground, are white. Such eggs do not need 



NEST AND EGGS OF CHIMNEY SWIFT 

 Photographed by B. S. Bowdish 



the protection of coloring matter, as do those which are laid in open nests, 

 and are thus exposed to the eyes of many enemies. 



The Swift is a very valuable bird, as is shown by the following letter 

 written February 23, 1911, by Mr. W. L. McAtee, of the United States Bio- 

 logical Survey: 



"My investigat'on of the food of the species is complete to date, and I 

 hope to prepare a pubHcation on the bird before very long. I may state, how- 

 ever, that the bird's food consists almost wholly of insects, and that beetles, 

 flies and ants are the principal items. It gets many beetles (Scolytidae), the 

 most serious enemies of our forests, when they are swarming, and takes also 

 the old-fashioned potato beetle {Lema trilineata), the tarnished plant-bug 



