GREEN, GREENISH GRAY, AND OLIVE 421 



Geographical Distribution: Lower California, Southern California, Ari- 

 zona, and Western Mexico. 



Breeding Range: In southern part of California, hoth east and west of 

 the Sierra Nevada. 



Breeding Season : On desert side of mountains, breeds in February ; on 

 the coast side, in May. 



Nest: Of plant down or fine shreds of vegetable fibre; lined with 

 feathers, and covered with lichen, bark, and leaves ; fastened in 

 place by spider web. On bushes, 1 to 6 feet from ground. 



Eggs: 2 ; white. Size 0.48 X 0.31. 



The Costa Hummingbird is a haunter of the desert 

 plains and barren mountain ranges of Southeastern Cali- 

 fornia, where it nests in the branching cactus. On May 

 16 a nest containing one egg was discovered on a low 

 branch of a willow five feet from the ground. The 

 mother was brooding, and refused to leave until forced 

 to do so. The next morning there were two tiny white 

 eggs. Incubation lasted thirteen days, the young emerg- 

 ing from the shell on the twenty-ninth. At first they 

 were very tiny, naked, grayish bits of bird life with black 

 skinny knobs for eyes, more like worms thau humming- 

 birds; but they grew surprisingly fast, and at the end 

 of the fourth day were covered with yellowish white 

 down on their backs and tops of their heads. By the 

 sixth day this had spread to the wings and rump, the 

 edges of the former began to show dark lines of needle- 

 like points where the pinfeathers were coming through. 

 On the eighth day they had more than quadrupled in 

 size, were darker in color, and were commencing to push 

 pinfeathers through the down. On the twelfth day they 

 seemed like miniature adults, for they were covered with 

 greenish feathers, the hair-like down still sticking out in 

 spots on the crown and back, but the plumage showing 



