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



This subspecies occupies the same general type of habitat as that 

 described for A. r. ruficeps in an earher section, composed of openly 

 spaced low shrubs with grasses or other herbs, or more rarely bare 

 ground between the woody plants. As its range extends from moist 

 coastal scrub areas near Santa Barbara to the borders of desert scrub 

 vegetation in the low mountain passes of interior southern California 

 and Baja California, the variety of shrubs it utilizes is probably 

 greater. George Willett (1933) considers this form to be "partial to 

 grass-covered hillsides," but Joseph GrinneU and Alden Holmes Miller 

 (1944) list its habitat as "Sparse low brush on grassy hill slopes [with] 

 preference * * * shown for tracts of California sage {Artemisia 

 calijornica) ." 



In northwestern Baja California these birds are apparently abun- 

 dant. George Willett (1913) writes that the species "was more plenti- 

 ful in the hills near Point Banda, below Ensenada, than I have ever 

 seen it anywhere else." Near the mouth of the Santo Thomas River 

 in the same general area, Laurence M. Huey (1941) also found greater 

 numbers than he ever observed elsewhere, "both on the hillsides facing 

 the sea, and in the grassy, brushless areas, which were beginning to 

 recover from incendiary fires." Joseph GrinneU (1926b) in describing 

 the race Iambi, now synonymized with canescens from northwestern 

 Baja California, says, "As usual they kept to a low, sparse, dry -hillside 

 type of chaparral ♦ * * ." 



Where I have studied them in the southern San Gabriel Mountains 

 of Los Angeles and western San Bernardino counties, Calif., rufous- 

 crowned sparrows are moderately numerous both in the coastal sage 

 scrub of the lower foothills where this has not been pre-empted by 

 cultivated or urban areas, and higher up in suitable places within the 

 lower half or so of the true chaparral belt, at least to 3,000 feet. In 

 the chaparral they are found only where steepness of slope or recent 

 fires have kept the shrubs low and open. Near Pasadena one foothill 

 plot of 41 acres of chamise chaparral that had regrown 7 years after 

 a fire to an average height of 4% feet with many openings between the 

 shrubs was estimated to hold five territories (.12 per 100 acres) in one 

 season (Murdock and Cogswell, 1942). Re- evaluation of the original 

 data, however, indicates that this was probably an overestimate, as 

 only two definite territories were wholly within the plot and two, 

 possibly three others partly in it. Comparable censuses of the birds 

 of a mature chaparral plot of 50 acres north of Arcadia (Cogswell, 

 1946, 1947, and 1948) included only 1 or 2 territories per year for an 

 average of 2.7 per 100 acres. Furthermore the birds were restricted 

 to a steep rocky slope and to the lower altitude portion of a gentler 

 south-facing slope where the shrubs were shorter and of more open 

 arrangement than elsewhere in the plot. 



