448 BULLETIN 17 6, UNITED STATES NATIONAL MUSEUM 



ing his winter visit to the Sierra de la Laguna (November 27-December 2), 

 the "whole top of the cold, sleety mountain was alive with Xantus's Hummers, 

 which seemed to be attracted there by an abundant shrub covered with dry 

 yellow blossoms, whereas in May and June they were confined quite closely to 

 the canons." The truth of the matter probably is that their movements, like 

 those of most other members of this family, are dependent largely on the 

 presence or absence, at any given locality or season, of the flowers on which 

 they feed. 



Chester C. Lamb (1925) evidently agrees with Mr. Brewster as to 

 the center of abundance of this hnmmingbird, which he says is "in 

 Laguna Valley, in the heart of the Sierra de la Laguna, situated south 

 of La Paz." He continues: 



These mountains are difficult of access, and it takes two days on mule back, 

 over tortuous trails, to reach Laguna Valley, a small, uninhabited valley at an 

 elevation of about 5500 feet. The Xantus Hummingbirds radiate out from this 

 valley in all directions, and are very common in all the mountain canyons, 

 right down to the open deserts. One may get into some of the favorable hum- 

 mingbird localities of California and believe he has seen a great concourse of 

 hummingbirds, but half an hour's walk across Laguna Valley and around the 

 lower rim will astound one at the numbers seen. One day I endeavored in the 

 course of a short morning's walk to count the number of Xantus Hummingbirds, 

 but, going up to two hundred before the first hour, I gave up the actual count 

 and started to estimate. One cannot see this large number of hummingbirds 

 at any hour of the day, however. The very early morning hours are when 

 they appear in the greatest abundance. At this time they come out of the 

 oak and pine forests around the rim of the valley and seek a place to bathe, 

 and also to feed and play around a red flowering shrub that grows along the 

 stream on the floor of the valley. 



Nesting. — Mr. Lamb (1925) was at "Comondu from March 30 to 

 April 11, 1924, and during that interval twelve nests were dis- 

 covered." He says: 



At this altitude, 800 feet, the birds must start nesting early in February, as 

 all but three nests contained large young or eggs about to hatch. I would 

 not be surprised if they raised two broods annually at Comondu, though I did 

 not stay long enough to prove the fact or to learn the period of incubation. 



In their courting, the male Xantus Hummingbird does not fly up in the air 

 and make the parabolic dive that the Costa Hummingbird does, but there is 

 considerable chasing by individuals of one another around through the trees. 

 The nesting birds of Comondu, where there are no oaks, have an entirely 

 different style of nest building from those of the oak regions of the Sierra de la 

 Laguna. The Comondu birds are not particular as to what kind of a tree 

 they select in which to build their nests. The nests are usually placed low 

 above the ground, and they are always very close to running water. * * * 



At Comondu I noted two exceptions to the usual method of suspending nests 

 to twigs. In one case a nest was found saddled to the dry spike of a date 

 palm tree, and another was saddled on a dead limb of a fig tree. Other 

 trees in which nests were found at Comondu were avocado, olive, lemon, 

 orange, w'ater willow and cottonwood. * * * 



In the Sierra de la Laguna (Laguna Valley), nests are always in live oak 

 trees, not necessarily near water. I made diligent searches in the pines and 



