142 



BIRDS 



Figure 145. — Nest of Goldfinch. 

 Nest of altricial bird. 



build their nests in 

 tall trees, making them 

 conspicuous, but inac- 

 cessible. Still others 

 build like the oriole 

 at the end of slender 

 branches where they 

 are out of reach of 

 animals. Birds like 

 the kingfisher, sand 

 swallow, and puffins 

 build their nests at the 

 bottom of a burrow in 

 the ground. 

 136. Nest Building. — 



Birds show great variation in nest building. Some 



build a large nest with materials loosely put together; 



others build small nests of neatly woven material, and 



some birds, like cowbirds, build no nest at all, but lay 



their eggs in the nests of 



other birds and leave the 



work of caring for their 



young to the foster parents. 

 The number of eggs that 



birds lay in their nests varies 



from one to as many as thirty 



or forty. The time required 



to hatch the eggs varies from 



ten days to six weeks. Birds 



whose eggs hatch in ten days 



or two weeks are called al- 

 tricial (al-trl'shal : Latin, 



altrix, nurse), for such young 



are hatched helpless, blind, 



Figure 146. — Nest of Least 

 Bittern. 



