GAMBEL'S WHITE-CROWNED SPARROW 1327 



evidence of sexual interest between fiockmates in the Gambel's 

 sparrows wintering at Davis or at Santa Barbara. Indirect evidence 

 from collecting records suggests that members of a given breeding 

 pair may winter not only in separate flocks but at different latitudes. 

 John T. Emlen, Jr. (1943) found from examination of Gambel's 

 sparrow specimens at the Museum of Vertebrate Zoology and from 

 his own collecting records that the sex ratios are unequal. At Davis, 

 males outnumber females by more than 5 to 1. Emlen's findings are 

 in accord with my own less-exact figures for the proportion of males to 

 females in gambelii collected at Davis and in pugetensis taken at 

 Berkeley. I, too, recorded the preponderance of males to females by 

 about 5 to 1. That this is not entirely due to accidents of collecting the 

 bolder and more conspicuous males is indicated by the fact that 

 Emlen found Gambel's sparrow females outnumber males by almost 

 2 to 1 in the collections from the southern and eastern portion of the 

 winter range. As we have no evidence of disparity in numbers of 

 males and females on the breeding grounds of either race, at least 

 some of the breeding pairs must break up and repair to different locali- 

 ties in winter. 



At Mountain Village in 1950 the females must have gone directly 

 to the males' territories on arrival. I never found any wandering 

 free. Hence the day of arrival must also have been the day the bond 

 between the pair started to form or to re-form between mates of the 

 previous year. The interval between the day of arrival of the female 

 and the first observed copulation varied from 1 to 10 days for three 

 pairs. The same behavorial elements of singing, trilling, and postur- 

 ing were present as in the other two races. 



At College, on the other hand, the first females I found were not 

 followed by or following a male, and did not appear to be attached 

 to any particular area. They flew long distances, trilled, and postured 

 without any external stimulus that I could detect, and as they foraged 

 they poked into crevices and peered under tufts of dry grass. A few 

 days later all females I saw were paired. Each was followed closely 

 by a male, and she trilled and postured vigorously when he sang or 

 came near her. She continued to peer into crannies and under grass 

 tufts. Four days after I first saw a female I saw two pairs copulate 

 and watched others go through all the characteristic behavior pre- 

 liminary to coition. Also at this time the females were building nests. 



I have no evidence of polygamy in the Gambel's sparrow, but 

 color-banding adjacent pairs at Mountain Village revealed one case 

 where a male tried unsuccessfully for 3 days to steal the mate of a 

 neighboring male while his own female was completing her first clutch 

 and starting to incubate. The facts were as follows (Oakeson, 1954): 



