CALIFORNIA SHRIKE 159 



Several other adult shrikes were stationed in adjacent territories at 

 distances of 200 to 400 yards. That one of these birds was the female 

 parent of the young is highly probable. Elsewhere solitary females 

 were collected which were acting in the same manner as this male. 



Early in August apparently the same male shrike was observed at 

 Firebaugh. No j^oung were in evidence, and other shrikes repeatedly 

 were chased from the territory with much vigor. The bird was sing- 

 ing as frequently as in July but was in the height of the annual molt. 

 When shot, it proved to have gonads decidedly smaller than is normal 

 for the breeding season. At this same time several hundred solitary 

 shrikes were noted in the San Joaquin Valley ; not one pair was seen. 



By November some few California shrikes have become paired. 

 Members of a pair were seen 30 yards from one another near Fire- 

 baugh, and members of another were watched as they amicably oc- 

 cupied perches on fence rails on either side of a small country road. 

 A census on three days late in November revealed only three and a 

 doubtful fourth pair out of 93 individuals watched long enough to 

 determine their status. 



Pair formation seems to involve trial cliases and begging notes, which 

 doubtless aid in revealing the sex of a bird, or better, in inducing ap- 

 propriate differentiated response in birds of opposite sex. An ap- 

 parent example of incipient sexual interest was noted on November 30. 

 A shrike that had been watched for a short time was soon chased vio- 

 lently high into the air by the owner of the area. The chase was 

 accompanied by the sharp note, hzech^ several times repeated, indica- 

 tive of excitement and usually associated with combat. The intruder 

 was followed to the edge of the territory, whereupon the defender 

 stopped and engaged in a sexual display commonly seen in the breed- 

 ing season. This consisted of fluttering the wings and of begging notes 

 similar to the actions of females during the laying and incubating 

 periods. The bird that had been chased from the territory showed 

 no response, and the bird giving the display ceased and returned to one 

 of its lookout posts. Unfortunately, both individuals were not ob- 

 tained; the bird that had been driven away proved to be an adult 

 male. 



The two birds obviously were not paired at the time. There was 

 some form of sexual excitement in one of them, presumably a female. 

 The chasing perhaps was a sexual flight but, judged from nuptial activ- 

 ities observed in the spring season, the flight represented a defense of 

 territory. It appears to me that sexual excitation was awakening in 

 the defending bird but was not yet sufficient to overcome the impulse 

 to remain in solitary possession of the feeding territory. At this 

 season a few individuals had yielded to sexual impulses so far as to 

 tolerate association in a territory with a member of the opposite sex. 

 Most of the birds, however, either were in the undecided condition of 



