BIRDS' NESTS. 67 



treeless regions, and by birds who substitnte strings, 

 cotton, or rags for their usual nesting materials. 



Third, condition of the young at birth, whether 

 feathered or naked. The young of what are termed 

 " praecocial " birds are hatched with a covering of 

 downy feathers. Gulls, Ducks, Snipe, Chickens, Par- 

 tridges, and Quails are familiar members of this group. 

 Their young can run about soon aftei- Ijirth, and a well- 

 formed nest is not needed. But the young of " altricial " 

 birds are hatched practically naked and are reared in the 

 nest, which is therefore not only a receptacle for the eggs 

 during incubation, but a home. Thrushes, Sparrows, in 

 fact all Perching Birds, Woodpeckers, Hummingbirds, 

 and many others belong in this group of altricial birds. 



Fourth, temperament, whether solitary or social. 

 Hawks, fierce and gloomy, nest alone, while the cheery, 

 happy Swallows nest in colonies. 



Fifth, structure of the bird. The tools — that is, the 

 bills and feet — of some birds are more serviceable than 

 those of others. We should not expect a Dove to build 

 the woven nest of an Oriole, nor a Hummingbird to 

 fashion a Woodpecker's dwelling. 



Sixth, feeding habit. In some few cases feeding 

 habit may determine the chai-acter of the nest. For 

 instance. Woodpeckers, in securing their food from trees, 

 often make large excavations, which it is quite natural 

 they should have learned to use as nests. 



Seventh, inherited habit, or instinct. There seems no 

 reason to doubt that birds inherit their knowledge of nest- 

 building, for in several cases where liirds have been taken 

 from the nest and reared alone, they have afterward 

 constructed a nest resembling that of their species. It 

 would therefore appear that inherited haljit is a fact. 

 Through it we may explain not only the similarity in the 

 nests of the same species, but also certain habits for 



