146 U.S. NATIONAL MUSEUM BULLETIN 233 



The third case was more involved as indicated in the following de- 

 scription. On July 15, 1947, when first examined, the nest contained 2 

 eggs of the seedeater; the next morning there was a cowbird egg in it 

 as well; foui- days later a 2nd cowbird egg was laid in it, apparently 

 by a different female as far as could be judged from the dissimilarity 

 of the eggs; two days later Nye removed the last laid egg and a few 

 minutes later the female host was back on the nest, incubating. After 

 four days, the first cowbird egg hatched ; that same day Nye removed 

 the young parasite. The next day one of the host's eggs was missing 

 and a new, 3rd, cowbird egg was in the nest. Three days later the 

 nest was empty and deserted; a snake in the same tree was thought 

 to have been the predator. 



All the records refer to the race sharpei of the host and the race 

 ohscwus of the parasite. 



Common Redpoll 



Acanthis flammea (Linnaeus) 



Since most of the breeding range of this boreal finch is north of 

 that of the brown-headed cowbird, the redpoll generally is unavailable 

 as a host. A single instance of its being parasitized has been brought 

 to my attention from the files of the British Columbia Nest Records 

 Scheme. A nest of the common redpoll (AJ. flammea) containing 1 

 egg of its own and 1 of the cowbird {M.a. artemisiae) was found at 

 Castor, Alberta, on June 25, 1959. The nest was deserted when 

 found and both eggs were in addled condition. 



Pine Siskin 



Spinus pinus (Wilson) 



Generally, the pine siskin is ecologically allopatric with the brown- 

 headed cowbird, a fact which effectively protects it from the attentions 

 of the parasite. However, there are places where the two species 

 overlap and here the siskin occasionally is imposed upon. Eleven 

 such instances have come to my notice, distributed among the following 

 states: Iowa, Kansas, Nebraska, South Dakota; and in Canada: 

 Ontario and British Columbia. 



Klugh (1906, pp. 17-18) recorded three parasitized nests in Welling- 

 ton County, Ontario. These were the first cases to be known. Dales 

 and Bennett (1929, pp. 74-77) recorded a nest in Iowa containing 3 

 eggs of the siskin and 1 of the cowbird. The latter egg hatched and 

 the chick grew to the fledging stage as the sole survivor of the brood. 

 Swenk (1929, pp. 79, 82) noted two parasitized nests in Nebraska: 

 one at Child's Point, south of Omaha, on May 13, with 3 eggs of the 

 siskin and 1 of the cowbu'd; another at Lincoln, on May 16, with one 

 young siskin in the nest and a young cowbird on the ground beneath 



