LEAST VIREO 265 



hair, all firmly bound together ; the lining consists of the very finest 

 grass tops with a little cattle hair. It measures about 3 by 21/2 

 inches in outside diameter and at least 2 inches in outside depth; 

 internally it measures about 2i/4 by 1% in diameter and about 11/2 

 inches in depth. It contained four fresh eggs, two of the vireo and 

 two of the dwarf cowbird. 



A nest taken by Frank Stephens and sent to William Brewster 

 (1882) was "pensile between the forks of a small mesquite branch 

 about five feet from the ground, in a thicket of weeds and brusk" 

 A nest found by Dr. (xrinnell (1914) in the Colorado Valley "was 

 attached to the forking stalk of a guatemote five feet above the 

 ground. It would appear that many nests meet with disaster from 

 their being built, as they so often are, in openings between thickets. 

 These openings serve as passage ways for browsing cattle, which as 

 they crowd through, force the supporting branches aside and de- 

 molish the nests. Evidence of a number of instances of this type of 

 catastrophe came to notice. * * * A nest found April 24 on the 

 Arizona side, five miles above Laguna, was located three and one-half 

 feet above the ground on a horizontal willow branch, beneath and 

 darkly shaded by several small willow trees growing close together 

 at the margin of an overflow slough." 



Eggs. — The set of eggs for the Arizona vireo seems to consist of 

 either three or four, perhaps most commonly three. These numbers 

 often include one or two eggs of the dwarf cowbird. The eggs of this 

 subspecies are apparently indistinguishable from those of Bell's vireos 

 elsewhere. The four eggs taken by Dr. Grinnell (1914) were "dotted 

 very sparsely about the large ends with bay and hazel." The measure- 

 ments of 30 eggs average 17.0 by 12,6 millimeters ; the eggs showing the 

 four extremes measure 18.5 by 12.9, 17.2 by 13.2, 16.0 by 12.4, and 

 16.1 by 12.2 millimeters. 



Enemies. — This, like other races of Bell's vireo, is a common victim 

 of cowbirds. 



VIREO BELLI FUSILLUS Coues 



LEAST VIREO 



HABITS 



The name least vireo was appropriate when applied to all the vireos 

 of this species in the far West and Southwest, as it formerly was; 

 but it seems to be a misnomer for the California race, as its measure- 

 ments indicate that it is slightly larger than either the Arizona or the 

 Texas race. 



Ridgway (1904) describes it as "similar to V. h. arisonw, but still 

 grayer above and whiter beneath ; the upper parts between olive-gray 

 and mouse gray without distinct tinge of greenish olive except on 



843290—50 18 



