COSTA'S HUMMINGBIKD. 205 



111 Inyo Couut}', California, Costa's Hummer seems to be very commonly 

 found about the flowers of the squa^v cabbage, a species of Stanleya, also about 

 wild rose, plum, or cherry bushes (Prunus) growing in the canyons, as well as 

 about other shrubs and plants found in these desert regions. Nidification com- 

 mences sometimes early in January; several of its nests and eggs have been 

 taken in Los Angeles County, California, in February; throughout the greater 

 portion of its range, however, it is at its height during April and May, and at 

 least two broods are regularly raised in a season. Considering the small size 

 of most of our Hummingbirds, sixteen days, or even fourteen only, appears to 

 be an unusually long time to be required to hatch such a small egg, and it 

 seems to be entirely out of proportion when compared with many larger birds, 

 and in this respect this family shows its close relationship to the Swifts 

 (Cypseli), Avhere incubation lasts still longer. 



The nests of Costa's Hummingbird do not compare favorably in architec- 

 tural beauty with those of the preceding species; the materials used are not so 

 thoroughly felted or quilted together, and the inner cup has ordinarily a rather 

 slovenly appearance. It is externally composed of plant down or fine shreds 

 of plant fiber ; the outer walls are thatched more or less profusely, in different 

 specimens before me, with bits of gray lichens, fine shreds of bark, and small 

 dry leaves, and these are securely fastened in place by spider web and silk 

 obtained from cocoons. The inside is lined with plant down, and occasionally 

 with finely shredded plant fibers and small, fluffy feathers. In some examples 

 feathers are very prominent among the inner lining. An average specimen 

 measures If inches in outer diameter by 1 inch in depth. The inner cup is 

 about seven-eighths of an inch in diameter by one-half inch in depth. They 

 are usually placed in low situations, from 1 to 6 feet from the ground, rarely 

 higher, although Mr. W. E. D. Scott records one taken on May 5, 1882, near 

 Riverside, in southern Arizona, from the extremity of a cottonwood branch 35 

 feet from the ground. In the desert regions of southeastern California various 

 cacti, the different species of sage (Artemisici) and greasewood bushes (^Larrea), 

 while in the canyons ash, sycamore, scrub oak, palo verde, cottonwoods, and 

 willows, furnish their favorite nesting sites. The eggs resemble those of the 

 preceding species in shape and color, but they are somewhat smaller. 



The average measurement of twenty-three specimens in the United States 

 National Museum collection is 12.19 by 7.87 millimetres, or 0.48 by 0.31 inch. 

 The largest egg measures 12.95 by 8.13 millimetres, or 0.51 by 0.32 inch; the 

 smallest, 11.68 by 7.62 millimetres, or 0.46 by 0.30 inch. 



The type specimen, No. 24250 (not figured), from a set of two eggs, was 

 taken by Dr. A. K. Fisher in Shepherd Canyon, in the Argus Mountains, 

 California, on May 7, 1891, and the nest from which these eggs were obtained 

 was placed on a little fork of a greasewood bush, 2 feet from the ground, very 

 poorly built, and probably an old one from the previous year. 



