140 Sketches of Some Common Birds. 



to the dull brown of the female. It is noticeable that in 

 this mingling of the sexes and in the pompous efforts of 

 the males to impress the opposite sex with their dignity, 

 there is no attempt at pairing, and the males evidently 

 make no demonstrations for the edification of any j^artic- 

 ular female. In fact, these birds are not known to pair 

 for the season or for life like most other birds. While 

 most writers state that the males are polysramous, it is 

 perhaps true that the females meet the advances of any 

 males which solicit their favors, and hence the females 

 may be described as polyandrous. However, careful and 

 persistent observation of the courting and breeding habits 

 of the species may disclose the fact that the birds pair 

 frequently for the summer. In a comprehensive article 

 on the species, published in the Ornithologist and Oologist, 

 January, 1890, Dr. Morris Gibbs suggests this as reason- 

 able, and refers to an incident coming under his notice 

 when he saw a blue jay, on the point of despoiling the 

 nest of a vireo, driven away by a pair of cowbirds in a 

 most valiant manner. On going to the nest he found a 

 large, overgrown cowbird occupying the largest share of 

 the structure, while a poor little red-eyed vireo occupied 

 a small space at the bottom, and beneath his big foster 

 brother. It thus appears that these birds do frequently 

 pair and also keep watch of the nest containing their off- 

 spring, though such action on the part of the cowbird is 

 rarely observed by ornithologists. 



The destructive effects of the visit of the cowbirds to 

 the nests they select in which to deposit their eggs are 

 very evident to the student of ornithology who is accus- 

 tomed to look for the birds in their haunts. Many nests 

 are found deserted by the owners apparently because a 

 cowbird had slipped into the habitation soon after the 

 completion of the structure and deposited its Qgg before 

 the owners had taken possession. I have found many 

 nests of the field sparrow and the chippy long deserted, 

 holding only a single addled Qgg of the cowbird. These 

 two species suffer greatly from the imposition of the para- 

 site, and I have frequently seen a pair of field sparrows 

 leading several younglings, among which would be a 



