CASSIN'S SPARROW 981 



Central and southern Mexico are presumed to be the species* 

 winter home. However, confirmatory specimens to enable one to 

 depict the species' winter and migration ranges even vaguely are 

 woefidly few in number, and until more specimens with adequate 

 data are available any delineation is mostly guesswork. 



Distribution 



Range. — Southeastern Arizona, southern Chihuahua (?), and ex- 

 treme southern Texas south to southern Mexico. Breeding range 

 and winter range imperfectly known and await clarification by further 

 study. 



Migration. — Early dates of spring arrival are: Arizona — Huachuca 

 Mountains, May 17; Santa Cruz County, May 23. Texas — ^Lower 

 Rio Grande Valley, April 9. 



Late date of fall departure is: Arizona — Sulphur Springs Valley, 

 October 7. 



Egg dates. — Authentic egg dates are practically lacking. 



AIMOPHILA CASSINII (Woodhouse) 



Cassin's Sparrow 



PLATES 53 AND 54 



Contributed by Frances C. Williams and Anne L. LeSassier 



Habits 



Cassin's sparrows are small, nondescript, ground-dwelling birds. 

 Unless they are singing they are rarely seen, as their plumage blends 

 perfectly with the dry grasses among which they spend their hves. 



This species is most abundant in the short grass plains of western 

 Texas and Oklahoma, eastern New Mexico, and Colorado. Although 

 open, grassy areas with a few scattered shrubs are preferred habitat, 

 in western Texas these fringilhds also occur in mesquite grassland 

 areas if the mesquites are small with open areas among them. When 

 found near draws where trees and thick brush grow, Cassin's sparrows 

 remain on the open slopes, rarely going into the brushy areas at the 

 bottom of the draw. They are almost never found in chaparral 

 thickets. 



J. Van Tyne and G. M. Sutton (1937) observe that this species 

 shows a marked preference for open, grassy country in Brewster 

 County, Texas, but found it occurs also in less open, more brushy 

 sections. They state that it is abundant in the yucca-dotted grass- 

 lands north of Marathon, where the concentration of singing males 

 gives somewhat the effect of a colony. 



