904 U-S. NATIONAL MUSEUM BULLETIN 237 part 2 



cacti, weeds, and what little grass escapes the inevitable cattle. This 

 is marginal habitat for Aimophila, but it was definitely occupied in 

 1958. 



Riparian habitat: Here water still flows more or less throughout 

 the year. High waters flood the bottomlands occasionally, producing 

 originally "bunches of tall rye [=sacaton] and mesquite grasses" 

 (Bendire, 1882). These habitats were soon grazed to destruction in 

 Arizona, but many remain in Sonora, where they have not been 

 studied. The closest approach in Arizona now (in the range of our 

 sparrow) is lower Sabino Creek, leaving the Santa Catalina Moun- 

 tains. Near its rocky bed, this creek has some broad-leafed riparian 

 trees (willow, cottonwood, ash, etc.) ; farther back, lower mesquite 

 trees dominate, with considerable tangles of weeds and grass in 

 ungrazed spots. 



Originally, C. E. Bendire (1882) found his new sparrow "particu- 

 larly partial to a strip of country . . . then covered with good sized 

 mesquite trees interspersed with sage and thorn bushes, small under- 

 growth," and grasses. They were "seldom any great distance" from 

 these woods "in the dry and arid cactus covered plains." 



Farmland habitat: Back from the now-dry bed of the erstwhile 

 Santa Cruz River, Papago Indians have for years farmed fields in 

 what was once, centuries ago, a dense thicket of mesquite woods. 

 Irrigation ditches border the fields; along them grows a profusion of 

 weeds, grass, and often a hedgerow of mesquite trees, elderberries, 

 and brush, chiefly Condalia lycioides. The principal study area here 

 is that of Joe T. Marshall, Jr., near the silted-over Indian Dam (see 

 map, fig. 16, in MarshaU, 1960). Here the birds inhabit the edges 

 of the brushy and cleared parts. After the early 1950s, with the 

 iUness and death of the owners, these fields were not irrigated and 

 received only normal rainfall. The nearby river, not visited by the 

 sparrows, ceased trickling regularly in the late 1940s and is now dry. 



Deep-soil habitat: This is very near the farms just mentioned, 

 but on the east rather than the west bank of the river and perhaps 

 200 meters farther north, below the dam site. The mesquite trees 

 are somewhat more cut over and spaced apart, though rather taller; 

 often they are overgrown with vines or have weedy tangles below. 

 Many clumps of taU sacaton grass, in the openings between trees, 

 are a sad remnant of the day when the river slowly sank into the soil 

 here, to reappear below. With the subsequent deep channeling, 

 this is now the driest of the occupied habitats, the most dependent 

 on day-to-day rainfall. 



Because the time of nesting may vai-y widely from year to year 

 at the same spot owing to ecological factors, most or all of which 

 depend on rainfall, we must understand both the normal climate 

 and the rainfall pattern of the abnormal years when the birds reacted 

 differently. Usually almost no rain falls between March and the end 



