410 BULLETIN 191, UNITED STATES NATIONAL MUSEUM 



groves or mattes in open or semi-open country ; city shade trees ; ravines, 

 gullies, and canyons among the hills; oak-clad crests of hills; telegraph 

 poles along railroad rights-of-way." 



Mrs. Bailey (1902) says that "Mr. Bailey found the black-crest one 

 of the most abundant birds of the Upper Sonoran zone, flying about 

 conspicuously among the junipers, nut pines, and scrub oaks." 



Nesting. — Like others of the genus, Bennett's titmouse builds its nest 

 in natural cavities in trees, stumps, or posts, in old woodpecker holes, 

 or in bird boxes. Mr. Simmons (1925) says that the nest may be placed 

 anywhere from 3 to 22 feet above ground, averaging about 10 feet; he 

 says the commonest locations are "hollows in live oaks, next commonest 

 in fence posts and bird boxes, then boxed fence posts, elms, hachberries, 

 cedars, telephone poles and post oaks." He found one nest on the top 

 of an old mockingbird's nest in a well-sheltered tree. 



He says that the nest consists of "a mass of rubbish composed of 

 cowhair, rabbit fur, green lichens, cedar bark, green moss, cotton, 

 feathers, and oak blossoms ; and occasionally small bits of inner bark and 

 bark fiber, grass, wool, soft down, leaves, rootlets, a stick or two, hemp 

 string, tissue paper, onion skins, and felting materials." It is "lined 

 with soft short cowhair, rabbit fur, opossum hair, wool, cotton, and 

 occasionally horsehair, soft down, feathers, and snake skin." The bottom 

 of the cavity is filled with green moss to a depth of from 2 or 3 inches 

 in one case to as much as 36 inches. He and others have reported that 

 pieces of cast-off snakeskin are usually found in the nests ; these and 

 the tissue paper and onion skin may be used to give resiliency or ven- 

 tilation to the nest ; this is evidently a characteristic habit of the species, 

 as it is with the crested flycatcher, under which it is more fully discussed. 



Eggs. — The eggs of Sennett's titmouse vary in number from four to 

 seven; of 25 sets, recorded by Mr. Simmons (1925), 5 were sets of 

 seven, 12 of six, 5 of five, and 3 of four eggs each. The eggs are ap- 

 parently indistinguishable from those of the other black-crested titmouse, 

 under which they are more fully described. Albert J. Kirn writes to me 

 that he once found a nest containing twelve eggs ; and once he found 

 a nest with two eggs of the titmouse and two of the dwarf cowbird, 

 which was afterwards deserted. The measurements of 40 eggs average 

 17.9 by 14.1 millimeters; the eggs showing the four extremes measure 

 19.3 by 14.3, 18.0 by 15.0, 16.1 by 14.0, and 18.4 by 12.6 millimeters. 



Food. — Although no careful analysis of the food of this titmouse 

 seems to have been made, it is probably similar to that of the closely 

 related tufted titmouse, about two-thirds insects in various forms and 

 about one-third vegetable matter. It seems to be very fond of cater- 

 pillars and searches the limbs and trunks of trees for hidden insects, their 



