NUTTALL'S WHITE-CROWNED SPARROW 1293 



row (Z. I. pugetensis) comprises populations with every degree of 

 migratory instinct, from those in northern California that forsake 

 their territories in winter to flock only a few hundred yards away, to 

 those of the Canadian border that fly a thousand miles each year 

 between wintering and breeding grounds. This race begins nesting in 

 early to late April, depending upon the latitude of the breeding 

 population in question. Gambel's sparrow (Z. I. gambelii) is a strongly 

 migratory race. It starts to nest in late May and early June in 

 Alaska, and in the provinces and the Northwest Territories of Canada. 

 The mountain white-crowned sparrow (Z. I. oriantha) is also migra- 

 tory, and begins to breed from late May to early July in Alberta and 

 the western United States, depending upon when the high mountain 

 meadows become sufficiently free of snow to permit nesting. 



Beneath this variability in migratory instinct and in the timing of 

 the breeding cycle lie patterns of behavior common to all four races — 

 the themes on which the variations are based. During territory 

 establishment and defense, courtship, nest-building, incubation, and 

 care of the young, the behavior is similar in all races. Therefore the 

 accounts in the section on "Habits" based on my observations of 

 NuttalTs sparrow at Berkeley apply also to the Puget Sound sparrow 

 and Gambel's sparrow during comparable phases, and also to the 

 mountain white-crowned sparrow insofar as my limited field work on 

 this race permits comparisons. In fact, so similar is the behavior in 

 all populations of white-crowned sparrows I have studied during the 

 breeding season, that as I watched them I felt as if I were seeing the 

 same birds, whether in central California, at the Canadian border, 

 or in Alaska. Such racial variations as do exist lie not in the behavior 

 patterns themselves but in the time of year the patterns emerge, and 

 in the duration of the successive phases of the nesting cycle. These 

 variations will be described in the sections under each race, which 

 follow the general account for the species. 



Where the observations are neither my own nor quoted from pub- 

 lished accounts cited in the bibliography, I refer in the text to the 

 observer who, through personal communication, supplied me with 

 the data. If no citation is made, the statements are based on my 

 field work done in the following localities for the periods stated: 

 Z. I. nuttalli. California: Berkeley (five years). 



Z. 1. pugetensis. California : Berkeley (five winter seasons) ; Eu- 

 reka (one winter and one spring). 



Oregon: Tillamook (one spring). 



Washington : Friday Harbor (one spring and sum- 

 mer). 



