502 LAND BIRDS 



In several nests, May 20, when the watch began, the 

 young were nearly ready to. fly, and their little heads 

 were stretched over the edge as if they were trying to 

 gather up courage to make the dive. In other cases the 

 broods were much later. Incubation required twelve 

 days, and in this the male shared equally with the 

 female, seeming fully as much at home on the nest as 

 did she. It was delightful to see them sit side by side 

 on the edge, turning their little blue heads sidewise as 

 they peeked into the cradle and talked it all over to- 

 gether in low sweet twitters. And when the nestlings 

 were finally hatched, one need not climb to discover the 

 fact, for the busy importance of the happy housekeepers 

 told all who had eyes to see. The young were fed by 

 regurgitation until two weeks old, and then the diet 

 was varied by an occasional large insect that looked like 

 a bluebottle fly. 



614. WHITE-BELLIED SWALLOW, OR TREE 

 SWALLOW. — Tachydneta bicolor. 



Family. — The Swallows. 



Length: 5.00-6.25. 



Adult Male : Upper parts iridescent steel blue ; lores deep black ; wings 



and tail blackish, slightly tinged with gi-eenish ; under parts pure 



white. 

 Adult Female : Similar to male, but upper parts duller. 

 Young ; Upper parts dull brownish slate. 

 Geographical Distribution : Whole of North America, migrating in winter 



to the Gulf States and West Indies. 

 California Breeding Range : Chiefly in upper Sonoran zone, west of the 



Sierra Nevada. 

 Breeding Season : May, June, and July. 



