HOST RELATIONS OF PARASITIC COWBIRDS 61 



compartments and the fact that later he fomid broken cowbird eggs 

 on the gromid below certainly suggest that the eggs were deposited in 

 the nests and then subsequently ejected. Because Mr. Barnum 

 actually had not seen the cowbird eggs in the martin nests, I have with- 

 held this record for many years. Inasmuch as no additional instances 

 of the cowbird parasitizing the purple martin have come to my notice 

 since then, I can assume only that this swallow is molested rarely by 

 the parasite but that such a situation did occur at the time of the 

 original observation. The nominate races of both the swallow and the 

 cowbird are involved here. 



Blue Jay 



Cyanocitta cristata (Linnaeus) 



The blue jay is an uncomm.on victim quite unsuitable as a potential 

 fosterer for a brown-headed cowbird. The eggs of the former are so 

 much larger than those of the cowbird that any eggs of the latter in a 

 nest would hardly have sufficient contact with the body of the incu- 

 bating host to allow them to develop and hatch. There are a few 

 records, which can be listed as follows: Blocher (1933, p. 58; 1936, 

 p. 132) found the blue jay to be parasitized at Amboy in northern 

 Illinois ; in the first of his two papers he reports a nest on May 22, 1932, 

 containing 4 eggs of the jay and 1 of the cowbird; in the second 

 paper he records what appears to be a similar instance in 1934, in the 

 same locality, but his wording is too inexact not to rule out the pos- 

 sibility that both refer to the same case; F. B. Webster (1890, p. 31) 

 stated that he had a parasitized set of blue jays' eggs in his collection 

 but gave no details; finally, the late T. S. Roberts (inlitt.) informed 

 me many years ago that he had a distinct recollection of finding, at 

 least once, the egg of a cowbird in the nest of a blue jay. The eastern 

 race of the parasite, M.a. ater, and the northern race of the jay, C.c. 

 hromia, are the forms involved in all of these records. 



Common Crow 



Corvus brachyrhynchos Brehm 



One indefinite record of this unexpected host — unfortimately 

 without details — should be mentioned here. In Feathers, the journal 

 of the Schenectady Bii'd Club, in the issue of February 1941 (p. 15), 

 there is given a list of "cowbird-raisers" in the vicinity of Buffalo, 

 New York. Among the 41 listed species is the crow. The statement 

 is made that all of the species listed are in "the records of the Buffalo 

 Ornithological Society." Some years ago, however, the late James 

 Savage tried in vain to fuid anything further about the basis for the 

 inclusion of the crow in the list. While it obviously is possible that a 

 brown-headed cowbird, with an egg ready to be laid, may be forced 



