420 BULLETIN 195, UNITED STATES NATIONAL MUSEUM 



A study of old nests reveals the fact that the breeding season is long past by 

 the middle of May. It does not begin, however, until well into March. The 

 sites chosen are, of necessity, in small bushes, but there is a consistent pref- 

 erence for those which afford the maximum protection. That desire satisfied, 

 the birds indifferently build in the heart of the shrub or near its outer edges. 

 The foundation is composed of thorny twigs from 3 to 6 inches in length. They 

 support a cup which, in thickness and size, is midway between that of the 

 shrike and that of the San Lucas Thrasher. The inside walls and especially 

 the bottom of the cavity are padded rather than lined . 



The habitat of these thrashers harmonizes well with their dull gray backs and 

 lighter underparts. They are decidedly ground-loving birds, skulking from 

 bush to bush and seldom flying. When alarmed, unless the fright is too sudden, 

 they run from danger. This they do with surprising speed, taking to the air 

 only as a last resource. The southern shore of San Ignacio Lagoon is their 

 metropolis in our cross section, but even there the birds are quite rare. In 

 3 days we saw not more than a dozen. 



The eggs of the desert thrasher are like those of LeConte's thrasher. 

 The measurements of 10 eggs average 26.8 by 19.3 ; the eggs showing 

 the four extremes measure 29.0 by 20.0, 25.4 by 19.3, and 26.4 by 18.7 

 millimeters. 



TOXOSTOMA DORSALE DORSALE Henry 



CRISSAL THRASHER 



Plates 85, 86 



HABITS 



Although the range of the crissal thrasher coincides in a very general 

 way with much of the ranges of the three other desert thrashers, its 

 haunts and chosen habitats are quite different from those of the others, 

 and they seldom overlap to any extent. LeConte's thrasher lives in 

 the hottest, driest, and most open deserts; Bendire's and the curve- 

 billed thrashers are found on the slightly more fertile deserts and 

 valleys, where there is more vegetation, and about the ranches ; but the 

 crissal thrasher seldom ventures out onto the desert and prefers the 

 more fertile valleys, canyons, and hillsides, where it can hide among 

 the more abundant vegetation and in the dense thickets, often in the 

 vicinity of water. 



What few crissal thrashers we saw in southern Arizona were found 

 in the belts of small mesquites, creosote bushes, and sagebrush that 

 grew along the arroyos, in low bushy underbrush in the valleys, in 

 the willows along a ditch in the San Pedro Valley, and on the rough 

 sides of the Dragoon Mountains, where mesquites, junipers, and 

 straggling bushes grew among the rocks. They were not very common 

 and were always shy and retiring. 



Frank Stephens told Mr. Brewster (1882a) that "he found the 

 Crissal Thrasher in copses in valleys, and along streams. It was 

 especially fond of well-shaded undergrowth, and spent much of its 

 time on the ground, searching for food under the bushes. It never 



