HOST RELATIONS OF PARASITIC COWBIRDS 133 



found broken cowbird egg shells directly beneath the pendant nests 

 of Baltimore orioles and asked whether orioles occasionally throw 

 out the parasitic eggs. No one yet has produced any evidence on 

 this point. If it were found that these birds do eject the strange 

 eggs, this factor might play a role in the apparent paucity of records 

 of cowbird parasitism. 



Gregg (1891, p. 26) found a nest in Chemung County, New York, 

 containing a nearly fledged cowbird "big enough to fly" and two 

 orioles much less advanced in development. Nauman (1930) watched 

 the development of a young cowbird which was reared in the nest 

 of a Baltimore oriole in Iowa. 



The northwestern records involve M.a. artemisiae. T. E. Randall 

 wrote me many years ago that he had found a parasitized nest in 

 Alberta; Street (Houston and Street, 1959, p. 176) found another at 

 Nipawin, Saskatchewan. 



The Baltimore oriole may at times cover over a cowbird egg with 

 a new nest floor. Parshall (1884) discovered a deserted nest con- 

 taining 3 eggs of the oriole and 3 of the cowbird plus 3 more eggs of 

 the parasite imbedded under a new nest lining. 



Bullock's Oriole 



Icterus bullockii (Swainson) 



Bullock's oriole is a rarely parasitized bird. I have learned of very 

 few records, all of which are mentioned here. This species was listed 

 by Bendire (1895, pp. 442, 448) as a host of two races of the cowbird, 

 ater and obscurus. He wrote that "Bullock's Oriole may occasionally 

 rid herself of the parasitic egg; at any rate I noticed the remains of 

 one lying under a nest of this species, Avith portions of one of her own. 

 The nest contained only three eggs of the rightful owner and the bu'd 

 was sitting on these." He found it occasionally parasitized in Ai-izona 

 but he did not list specific instances. In Oklahoma, R. C. Tate found 

 a nest of Bullock's oriole on July 12, 1911, with one young oriole and 

 two young cowbirds; two dead young orioles were on the ground 

 beneath the nest (Nice, in litt.; also 1931, p. 169). A parasitized set 

 of eggs was taken in Baylor County, Texas, May 14, 1952, by T. C. 

 Meitzen (in litt.). Mr. Griffing Bancroft wrote me years ago that 

 he had collected a set of 5 eggs of this oriole with 1 of the dwarf cow- 

 bird in Imperial County, California, on May 18, 1921. Another 

 parasitized nest, also found in Imperial County, on May 18, 1919, 

 is now in the collections of the Western Foundation of Vertebrate 

 Zoology. Linsdale (1949, p. 251) found Bullock's oriole feeding a 

 recently fledged cowbird at Robles del Rio, California. The California 

 records involve the race parvus of the host; the Arizona, Texas, and 

 Oldahoma records, typical bullockii. 



