22 NESTING HABITS OF WARBLERS 



CLASS III. WARBLERS WITH A FLIGHT SONG. 



Prothonotary, Golden-winged (?), Nashville, Orange-crowned, 

 and Tennessee (?) Warblers, Oven-bird, Northern Water-Thrush, 

 Louisiana Water-Thrush, Mourning Warbler, Northern Yellow- 

 throat and races, Worm-eating Warbler, Chat. 



NESTING HABITS OF WARBLERS 



Although only the three Seiuri, among our fifty-five species of 

 Warblers, may be considered truly terrestrial, no less than nine- 

 teen species nest upon the ground, and fifteen more usually nest 

 within less than three feet of it. There is, in general, a relation 

 between the color of the bird and the character of its nesting- 

 site. The terrestrial species are, as might be expected, dull colored, 

 but even among the arboreal species which nest on the ground, 

 striking colors are less frequent than among those which nest in 

 trees. A marked exception to this rule, however, is presented by 

 Setophaga picta, which nests in banks, etc., although the female is 

 indistinguishable from the black and red male. 



Data do not exist upon which satisfactorily to ascertain the 

 comparative safety of ground and tree sites. While the former are 

 more open to attack by terrestrial predaceous mammals and snakes, 

 a nest in the trees is more likely to be visited by Crows and Jays. 



On the other hand, the Cowbird appears to be more partial 

 to a nest upon the ground, nearly one-half of the twenty-four 

 species of Warblers in whose nests its egg has been found being 

 ground nesters. On the whole, we may assume that the tree site 

 is the safer, and the fact that our most abundant Warblers nest 

 in bushes or trees gives this view some support. 



We have not as yet many intimate studies of the home-life 

 of Warblers but, so far as recorded observations go, it appears 

 that the nest is built by the female to the accompaniment of the 

 male's song. Occasionally the male is permitted to bring a bit of 

 nesting material but he apparently rarely takes part in the con- 

 struction of the home. 



The male Pine Warbler is said rarely to sit upon the eggs 

 but with this exception, I find no evidence that the male ever 

 assists in incubation. He, however, lives near the nest and may 

 at times feed the female while she is upon it. 



The period of incubation in Warblers, as far as it has been 

 ascertained, is ten or eleven days, but so little exact information 



