168 U.S. NATIONAL MUSEUM BULLETIN 233 



1 egg of the sparrow; two days later it held 2 sparrow eggs and 2 cow- 

 bird eggs; and two days later, again, it held 3 cowbird eggs, no sparrow 

 eggs, and the shell of another cowbird egg outside but near the nest. 

 The New York record refers to the eastern race of the cowbird, M.a. 

 ater; the others, to M.a. artemisiae. All refer to the typical race of 

 the sparrow. 



Swamp Sparrow 



Melospiza georgiana (Latham) 



The swamp sparrow is generally an uncommon victim of the brown- 

 headed cowbird. A number of authors have mentioned it as a host 

 without giving any details. Bendire, Davie, and others of the old 

 "egg collectors" have made such statements, but the actual records 

 which have been found are relatively few. Although the cowbird 

 frequents marshes during migration, it tends to leave marsh nests 

 alone. At Ithaca, New York, where both the swamp sparrow and the 

 cowbird are common, there were no records of parasitism on the 

 species. 



This sparrow has been found by Ferry (1910, pp. 199-200) to be a 

 molothrine fosterer in Saskatchewan; in Alberta, by Stansell (in litt.); 

 in Ontario, by several observers (eggs in museums of Toronto and 

 Ottawa); in Minnesota, by Currier (1904, p. 37); in Wisconsin, by 

 Gunderson (1948); and in Michigan, by Cook (1893, p. 88) and Berger 

 (1951). There are other records, mostly of parasitized sets, the data 

 of which are not available to me since they were in collections which 

 have been dispersed. In Michigan, Berger (1951, p. 28) reported an 

 unusual degree of parasitism on the swamp sparrow: he observed five 

 nests, four of which had been victimized by the cowbird. 



Although the swamp sparrow appears to be a rather uncommon 

 victim of the brown-headed cowbird in most areas where the two exist 

 together, it has been found to be a frequent and submissive host in 

 southern Quebec. Here, L. M. Terrill (1961, p. 10), between 1897 

 and 1956, found 322 nests of the swamp sparrow, of which 34, or 

 roughly 10 percent, contained eggs of the cowbird. He wrote that 

 the swamp sparrows in his area nested chiefly in sedgy tussocks among 

 small willows in shallow water. Apparently this environment was 

 more acceptable to the cowbirds than are the usual marshy areas. 



The Alberta and Saskatchewan records refer to the race ericrypta of 

 the sparrow and artemisiae of the cowbird; the Quebec, Minnesota, 

 and Michigan records involve the nominate race of both host and 

 parasite. 



Song Sparrow 

 Melospiza melodia (Wilson) 



The song sparrow is one of the most frequent, if not the most 

 frequent, victim of the brown-headed cowbird. Since the former is 



