HOST RELATIONS OF PARASITIC COWBIRDS 65 



May 5, 1912. The other instance was found by Jacobs (1923, pp. 

 19-20), presumably near Waynesburg. All four records involve the 

 subspecies cookei of the host and the nominate race of the parasite. 

 The Illinois set, taken in Knox County, May 12, 1942, by H. M. 

 Holland, is now in the egg collection of R. Kreuger, to whom I am 

 indebted for the data. 



Red-breasted Nuthatch 



Sitta canadensis Linnaeus 



This species is a recent addition to the list of parasitized birds, and 

 it is one that is not likely to be molested frequently by the parasite. 

 Houston and Street (1959, p. 176) Hst the red-breasted nuthatch as a 

 victim of the brown-headed cowbird (subspecies artemisiae) at Nipa- 

 win in the valley of the Saskatchewan River, Saskatchewan. When 

 the nest first was found, apparently it did not contain a cowbird's 

 egg. At that time the opening was enlarged to allow the observer to 

 reach inside and then the "portion that had been removed was replaced. 

 Later it was noted that the replaced portion had fallen away and the 

 nest was now found to contain an egg of the cowbird in addition to 

 those of the Nuthatch." The logical question arises, therefore, 

 whether or not the cowbii'd would have used, or would have been able 

 to use, this nest for its egg were it not for the enlargement of the open- 

 ing; and thus the question remains as to whether or not this bird 

 legitimately can be considered a natural host of the parasite. 



Brown Creeper 



Certhia familiaris Linnaeus 



A single instance of cowbu'd parasitism on the brown creeper has 

 been reported. Kumlien and Hollister (1902, p. 124) noted that at 

 Meridan, Wisconsin, late in June, 1897, J. N. Clark observed a pair of 

 brown creepers feeding a recently fledged cowbird. Since noisy young 

 cowbirds occasionally attract the attention of food-laden bu'ds in 

 addition to their own foster-parent, one may ask if Clark's observa- 

 tion constitutes a defuiite record of parasitism. Because of this and 

 also because most nests of the creeper would be inaccessible to the 

 parasite, an element of doubt cannot be eliminated — although the 

 probabilities are that the creepers were the actual fosterers. The 

 subspecies americana of the host and the nominate race of the parasite 

 are involved here. 



Wrentit 



Chamaea fasciata (Gambel) 



Two races of this little bird have been found to be victimized by the 

 small southwestern race of the brown-headed cowbird. The records 

 rest upon five occasions, all in California. Four of these instances 

 concern the pallid subspecies CJ. henshuvn. M.C. Badger informed 



