1294 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 3 



Z. I. gambelii. California: Davis (one winter season); Santa 



Barbara, (ten winter seasons). 

 Alaska: Mountain Village (one spring and 



summer) ; College (one spring, sum- 

 mer, and fall). 



Z. I. oriantha. California: Sierra Nevadas and Lassen National 



Park (one summer). 



Spring. — Spring is the time of transition from flocking to paired 

 isolation on mutually exclusive areas. Territorial jealousy and 

 sexual interest, which have been at low ebb during winter, emerge 

 and rise to maximum intensity. The male sings with increasing 

 frequency and vigor; he pursues and fights rival males, and the 

 female trills and postures. At first these elements of territoriality 

 and sexual interest may appear separately, unorganized into any 

 integrated behavior. Later they are woven into a characteristic 

 pattern. The end result is that pairs space out in orderly fashion 

 and stay on their territories at least until the young of the last brood 

 become independent. 



In early, mid, or late January, depending on the weather, the male 

 NuttalPs sparrow begins to sing more forcefully than in winter, more 

 frequently, and from a more conspicuous perch. The adult male 

 becomes less and less tolerant of the immature or mateless birds 

 that have spent the winter in his area. When their song also in- 

 creases in force and frequency, he pursues and attacks them until, 

 about 3 weeks after the beginning of this phase, he regains sole pos- 

 session of all or part of the territory he patrolled the year before. 

 With this achievement, if he is already mated, he stops singing ex- 

 cept for rare, weak songs. Boundary disputes or pursuits are also 

 rare. Settlement is now complete, some 7% weeks before incubation 

 starts. 



The immature or mateless males usually find mates during the 

 period of singing, pursuits, and fighting. If they do not, they con- 

 tinue to sing after the mated males are silent. If a male loses his 

 mate, he resumes loud singing and continues it until another female 

 joins him. 



Color-banding reveals that, except in instances of polygamy, 

 territorial jealousy is not expressed by the female NuttalTs sparrow. 

 Her weak song, which continues until nesting time, is not used for 

 advertisement or warning. I have never seen her join in a fight and 

 only rarely in a chase in which her mate was involved. In polygamy, 

 on the other hand, all elements of territorial jealousy appear. The 

 development of the territorial sense in the female independently of 

 the male is illustrated in the behavior, in 1935, of females I and III, 



