918 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 2 



and trim. The ground color of the side of the head is somewhat 

 paler, so that there is no obvious whitish ring around the eye. In 

 fresh plumage, a hint of white at the outer corners of the dark tail 

 when spread, will help distinguish it from both the rufous-crowned 

 and the chipping sparrow. The rufous bend of the wing can be 

 seen only under favorable circumstances. Voice and habitat are 

 the best clues, especially in early summer when chipping sparrows are 

 not apt to be present in the Lower Sonoran Zone. 



Enemies. — ^Little is known of those enemies of the rufous-winged 

 sparrow that man conventionally (or conveniently) discusses. In 

 the old mesquite thickets, C. E. Bendire (1882) found that its "nest 

 appears to be one of the most favored by" the brown-headed cowbird; 

 about one-half of the nests were parasitized, and in a number of these 

 the owner's (but not the parasite's) eggs were "minutely punctured in 

 one or more places," presumably by the cowbird. In the swale 

 habitat, however, I have found little parasitism by cowbirds, which 

 are scarce there. 



Undoubtedly the most important enemy of the rufous-winged 

 sparrow is the unscrupulous cattleman. The distribution of the 

 bird in the Tucson Valley during the 1930s and 1940s made this clear. 

 Those areas where colonies survived were never heavily grazed; 

 furthermore, they were in places where the grass derived its water from 

 rainfall in the immediate vicinity and was not dependent on a healthy 

 range above. The late J. J. Thornber of the University of Arizona 

 informed me that Hght grazing in the opening decades of the century 

 had largely replaced the once-dominant grama grass (Bouteloua 

 Rothrocki) with Aristida in these areas. But there was always 

 some sort of grass cover. The most flourishing colonies were around 

 meadows of tobosa {Hilaria mutica). This is good evidence that the 

 general abuse of the country by overgrazing exterminated the bird about 

 Fort Lowell and Oracle and sadly reduced its numbers along the 

 Santa Cruz River, so that the once marginal colonies became the 

 species' only strongholds in this region. 



Fall and winter. — After the young are grown, small (probably 

 family) groups of rufous-winged sparrows are generally found as- 

 sociating with such other sparrows as the black-throated, chipping, 

 and Brewer's. Where it was densely congregated in the mesquite 

 thickets, C. E. Bendire (1882) found the species "sociable and gre- 

 garious at all times," especially in winter, when "it is found in small 

 flocks." W. E. D. Scott (1887) found winter flocks of 4 to 20 individ- 

 uals, but some of these would seem to be exceptionaUy large. Recent 

 observers usually find only family-sized groups, which may associate 

 with other sparrows such as Spizellae. 



