426 U. S. NATIONAL MUSEUM BULLETIN 211 



near barns. * * * The gonads of these birds are smaller than those 

 of the only other Cowbirds then present (resident birds)." The males 

 of this group do not seem to take much notice of the females, whereas 

 the resident birds do, and, to some extent, so do the last of the migrant 

 males. "These two facts", says Friedmann, "point to the conclusion 

 that these birds are really the immature individuals." 



Territory. — Friedmann (1929) proved to his own satisfaction 

 that both the female and the male cowbird are confined to a definite 

 breeding territory: 



Not only has the female a definitely marked off breeding area, but the male has 

 a definite post, entirely comparable to the "singing tree" that Mousley describes. 



During the summer of 1921 numerous individual male birds were seen daily 

 on certain trees or on definite telegraph poles. From these perches they would 

 sing and display; they might fly off but would soon circle around and come back. 

 There was no question but that they were tied down to their respective singing 

 trees. In one case the identity of the male was made certain because of a peculiar 

 harshness of his song, and as this individual was to be found daily in the same tree, 

 it seemed safe to assume that each day the same bird was seen at a given perch. 

 Not only was a certain tree used by each male, but a certain part seemed to be 

 preferred, usually the higher branches. * * * 



That the female has a definite territory is not so easily noticed as she has no 

 "singing tree," and is, as in most birds, less conspicuous and less often seen than 

 the male. * * * 



At Ithaca in the late spring and summer of 1921 I found that certain females 

 (probably the same one in a given place each day) seemed to have definite terri- 

 tories. Just off the northeastern corner of the main quadrangle of the Cornell 

 campus is a small body of water called Beebe Lake. One pair of Cowbirds stayed 

 on the north shore of the lake, another pair on the south shore. I was sure that 

 the birds I saw on the north shore were not the same as those of the south side 

 because on several occasions I saw the pair on one side and simultaneously heard 

 or saw the birds on the opposite shore. All the Cowbird eggs found in each 

 territory were very similar to each other and uniformly different from those found 

 in the other. * * * 



The size of the territories is very variable, some being a mile or more long and 

 comparatively narrow, others * * * much smaller. * * * 



The Cowbirds do not make any very spirited attempts to defend their terri- 

 tories and consequently in regions of unusual abundance the territorial factor is 

 much less noticeable. I have never seen Cowbirds fight and their method of 

 defense is restricted to an intimidation display. 



The females are probably not always confined to definite territories 

 for their egg laying, for eggs evidently laid by two different females 

 are often found in the same nest. 



Mrs. Amelia R. Laskey, of Nashville, Tenn., has sent me notes on 

 her 3-years' study of cowbird behavior. She remarks on territory 

 and mating: "In the area about our home, in each of the three breed- 

 ing seasons, one male and one female became dominant. This area 

 may be called a 'domain' rather than a territory. The dominant male 

 and the dominant female used this area in their pair formation and 



