236 Bird - Lore 



or grasses, though grasses are regularly used by the Orchard Oriole. Marsh- 

 birds regularly use the dried sedges or rushes or marsh grasses; field-birds use 

 grasses and horsehair; woodland birds use dead leaves, mosses, and rootlets, 

 and so on. The materials with which a bird comes most in contact are the 

 ones employed in nest-building provided they conform to the general type of 

 nest characteristic of the family. 



Birds that spend a great deal of time on the wing and come less into contact 

 with nesting materials and nesting-sites show the greatest diversity both as 

 to site and materials. Among our common Swallows, for example, the Barn 

 and Cliff Swallows build nests of mud about barns or cliffs; the Tree Swallows 

 build nests of straws and feathers in holes in trees or bird-houses; the Bank 

 Swallows build similar nests at the end of holes which they excavate in sand- 

 banks; and the Rough-winged Swallows utilize old Kingfisher burrows or 

 natural crannies about cliffs or bridges or drain-pipes. 



The factors that control the selection of the nesting-site are primarily the 

 necessity for concealment, accessibility to the feeding-ground, and protection 

 from the elements. If birds were capable of worrying over the possibility of 

 the destruction of their homes, their heads would be white before their nests 

 were started. As it is, they go about the selection of the site instinctively and 

 finally decide upon one which is usually well concealed from their ordinary 

 enemies such as cats, Crows, Hawks, Owls, Jays, Grackles, Wrens, weasels, 

 skunks, raccoons, squirrels, rats, and snakes, as well as being fairly well pro- 

 tected from wind and rain, and accessible to their feeding-ground. The large 

 percentage of nests that are broken up, however, attests the many dangers 

 that ever beset the bird's home and the bird's life. I think it is no exaggeration 

 to state that less than 10 per cent of the nests which I find each year endure 

 until the young leave of their own accord. I would even venture to say that 

 not one in twenty of the nests that are started succeed in housing the young 

 to maturity. 



The many ways in which birds circumvent their enemies by building their 

 nests in inaccessible or inconspicuous places, or by decorating them with bits 

 of paper, cobwebs, or lichens so that they will look like something else, would 

 make quite a story in itself, but we must pass them over and merely mention 

 the birds that have changed their natural nesting-sites to suit changed con- 

 ditions. Some species are not adaptable and when conditions change they 

 vanish; others are able to make the best of changed conditions and may even 

 increase. Such are the Robin, all of the birds that nest in nesting-boxes, the 

 Phoebe, and the Barn and Cliff Swallows that formerly nested only on clifis 

 but are now so familiar about our dwellings. The Chimney Swift that has 

 almost forsaken the hollow trees for the chimneys is another good example of 

 adaptation. One often hears of birds nesting in unusual places, such as moving 

 street-cars or traveling cranes, under wagons left standing, in clothespin bags, 

 in the pockets of scarecrows, etc., but they are always of these adaptable 



