358 BULLETIN 17 6, UNITED STATES NATIONAL MUSEUM 



the back shows a mixture of dusky and glossy green, the latter 

 feathers tipped with buffy ; the throat and abdomen are dull white ; 

 the flanks are light drab; and the remiges, except the middle pair, 

 are tipped with dull white. This plumage, which is much like that 

 of the adult female, is apparently worn through most of or all the 

 summer ; I have seen it in its purity as late as August 24 ; but I have 

 seen young males that were beginning to acquire a few violet feathers 

 in the gorget as early as July 20. Progress toward maturity is 

 rather slow and is prolonged through the winter ; I have seen young 

 males with imperfect gorgets in February and as late as May 15. 

 As the ruby-throated hummingbird is said to have a complete molt 

 in spring, this may also be the case with the black-chinned, which is 

 so closely related; if this is so, the fully adult plumage must be 

 acquired at this molt. Ridgway (1911) says that the young male is 

 "similar to the adult female, but feathers of upper parts margined 

 terminally with pale grayish buffy, under parts more or less strongly 

 tinged or suffused with pale buffy brownish, and throat always ( ? ) 

 streaked or spotted with dusky"; and that the young female is 

 "similar to the young male, but throat usually immaculate or with the 

 dusky spots or streaks smaller and less distinct." 



Adult females are considerably larger than adult males, the wing 

 averaging nearly 10 percent longer. This seems to be more or less 

 true of all the species of Archilochiis and Selasphorus. 



Food.- — Tlie black-chinned, like other hummingbirds, feeds on 

 insects and sweets, mostly obtained from various flowers. It does not 

 seem to be very particular in its choice of flowers in which to forage, 

 though I was greatly impressed in California with the popularity 

 of the "tree tobacco" {Nicotiana glauca) as a feeding ground for this 

 and other hummingbirds. This is a small tree or large shrub that 

 grows from 12 to 20 feet high and bears numerous clusters of slender, 

 yellow, tubular flowers. The hummers frequent these little trees in 

 large numbers; Major Bendire (1895) says that R. H. Lawrence saw 

 some 70 or 80 hummingbirds in a patch of wild tobacco in less than 

 two hours. The same observer noted that this and Anna's and Costa's 

 hummingbirds "were attracted by a bright red flower {Delphinium 

 cardinalis) growing on a clean, slender, juicy stalk, from 2 to 6 feet 

 high." 



In the Santa Rita Mountains, Arizona, Mrs. Bailey (1923) took one 

 "feeding from the orange-colored tubes of honeysuckle {Anisocanthics 

 thurberiy \ its throat was full of nectar; others were seen about the 

 red terminal blossoms of ocotillo. In the Colorado Valley, Dr. 

 Grimiell (1914) found it feeding about the flowering bushes of 

 LyciwfYi andersoni.^ about the profusely blossoming palo verdes, and 

 about the lavender flowers of ironwoods. George Finlay Simmons 

 (1925) says that, in Texas, it "hovers and feeds about the laterally- 



