THE COWBIRDS. 593 



the labor and care of rearing- its young. It appears to be entirely 

 devoid of conjugal aftection, and practices polyandry, tbe small flocks 

 in which it is found during the season of reproduction generally con- 

 taining several more males than females. 



It is at all times more or less gregarious, especially so in fall and 

 winter, when it often forms large Hocks, and associates then Avith the 

 other blackbirds, like Brewer's and the Red-winged. 



The laying season rarely begins before May 15, and continues for 

 about two mouths. During this time probably from 8 to 12 eggs are 

 laid by each female, or the equivalent of two broods, and I believe that 

 several days elapse between the laying of each egg. It is not likely, 

 and this is very fortunate indeed, that more than half of these eggs 

 are hatched, as some are occasionally dropped in old and abandoned 

 nests, or, when the female is hard pressed, even on the ground; others 

 in just completed nests in Avhich the rightful owner had not yet laid, 

 and. seeing the parasitic egg in its nest, either abandons it entirely or 

 constructs another over the first, burying the stranger egg among the 

 building material. 



When the Cowbird is ready to lay she quietly leaves her associates 

 and begins her search for a suitable nest, usually selecting one of a 

 species smaller than herself, but if such a one is not readily found a 

 nest of a larger bird will answer equally well, especially if the full 

 complement of eggs has not been deposited in it. She does not forcibly 

 drive the owner from her nest, but watches her opportunity to drop her 

 egg in it when it is unguarded. In rare instances only will a fresh 

 Cow bird's egg be found among incubated ones of the rightful owner. 

 I have only observed this on a single occasion. From 1 to 7 of these 

 parasitic eggs have been found in a nest, the larger numbers usually in 

 those of ground-building species, especially in that of the Ovenbird, 

 where from 3 to 5 eggs, with perhaps 2 or 3 of the owner, are not 

 especially uncommon. I know of one instance where not less than 7 

 Cowbirds' eggs were found in a nest of this species with a single one of 

 its own. Kot unfrequently 2 or more eggs, in all probability laid by 

 the same bird, will be found in one nest. There is so much variation in 

 their eggs, both in size and markings, that the close resemblance of 

 any 2 eggs at once attracts attention. It is not unusual to find some 

 of the eggs of the species imposed on thrown out of the nest to make 

 room for those of the parasite, nor to find minute punctures in the 

 shells of some of the remaining eggs. This is possibly done on purpose 

 by the Cowbird with her beak, to keep the eggs from hatching, or with 

 her sharp claws while sitting on the nest and depositing her own egg. 

 I am inclined to attribute this puncturing to the latter cause, but there 

 is no doubt that the Cowbird sometimes throws the rightful owner's 

 eggs out of the nest purposely to enhance the chances of its offspring 

 coining to maturity. I have yet to see a punctured Cowbird's egg. It 

 is astonishing how many different species are thus imposed upon by the 

 H. Mis. 184, ])t. 2 38 



