66 BIRDS' NESTS. 



birds that nest in tliis manner resort to uninhabited 

 islets and secure protection through isolation. 



Some birds nest alone, and jealously guard the vicin- 

 ity of their home from the approach of other birds, 

 generally of the same species. Others nest in colonies 

 brought together by teniperament or community of 

 interests, and dwell on terms of the closest sociability. 



The material used by birds in building their nests 

 is as varied as the nature of the sites they select. The 

 vegetable kingdom contributes much the largest share. 

 Grasses, twigs, and rootlets are the standard materials ; 

 but plant-down, plant-fibers, bark, leaves, lichens, clay, 

 spiders' webs, hair, fur, and feathers are also used, Avhile 

 in some cases a gummy secretion of the salivary glands 

 furnishes a kind of glue. 



Birds have been classified, according to the manner 

 in which they employ these articles, as weavers, tailors, 

 masons, molders, carpenters, felters, etc. 



Sometimes both sexes assist in the construction of the 

 nest, or one bii'd collects the material while the other 

 adjusts it. Again, the female performs the task alone, 

 aided only by the encouraging voice of the male. 



The time of construction varies from one to two 

 weeks to as long as three months in the case of the South 

 American Ovenbird, who in June begins to build the 

 nest it will not occupy until October. The Fish Hawk 

 evidently believes in the value of a stick in time, and 

 often repairs its nest in the fall. 



Lack of space prohil^its a discussion of the influences 

 which assist in determining the character of birds' nests. 

 They may be summarized as follows : 



First, necessity for protection. 



Second, conditions imposed by locality. These affect 

 both the site and material, as illustrated by Doves, who 

 nest in trees in wooded countries and on the ground in 



