180 U.S. NATIONAL MUSEUM BULLETIN 233 



with the bronzed cowbird; accordingly, the two seldom would have 

 contact with each other. 



Orange-billed Nightingale-thrush 



Catharus aiirantiirostris (Hartlaub) 



This thrush has been noted as a cowbird host only two times, 

 Cherrie (1891, p. 273) saw a thrush (race C.a. costaricensis) feeding 

 a fledgling bronzed cowbird (race T.a. aeneus) near San Jose, Costa 

 Rica. In Morclos, 5 miles east of Cuernavaca, on June 10, 1959, 

 J, Stuart Rowley (mss.) found a parasitized nest with 3 eggs of the 

 host (race C.a. clarus) and 2 of the parasite (nominate race). 



Solitary Vireo 



Vireo solitarius (Wilson) 



Brandt (1951, p. 406) recorded a nest of this vireo (subspecies 

 V.s. plumbeus), with 3 eggs of its own and 1 of the western race of 

 the bronzed cowbird, which was found late in May, 1944, at Ramsay 

 Canyon, Arizona. Not only is this an addition to the known victims 

 of the parasite, the race of which in this case is T.a. milleri, but also 

 it is an instance of competition for hosts between the red-eyed and the 

 brown-headed cowbirds. The latter is prone to lay its eggs in nests 

 of vireos; the former appears seldom to use the vireo. 



Yellow -green Vireo 



Vireo flavoviridis (Cassin) 



I know of five instances of parasitism by the bronzed cowbird 

 on this vireo. Mr. E. J. Coiu-t told me many years ago that he 

 had at one time in his collection a set of eggs, collected in Costa Rica, 

 of the yellow-green vireo containing 1 Qgg of the bronzed cowbird. 

 A second record of this vireo as a host of the bronzed cowbird has 

 been mentioned by Skutch (1960, p. 26) and by Bent (1958, p. 462, 

 ex Skutch). The latter was shown a nest containing three nestlings of 

 the host and one of the parasite on July 25, 1935, in the Pacific slope 

 area of Guatemala. In Morelos, J. Stuart Rowley (mss.) found three 

 parasitized nests. In all these cases the nominate races of the host 

 and of the parasite were involved. 



Yellow-breasted Chat 



Icteria virens (Linnaeus) 



The yellow-breasted chat was recorded as a victim of the bronzed 

 cowbird near Brownsville, Texas, by Merrill (1877, pp. 85-87). He 

 examined many nests of the chat and, finding only one to be para- 

 sitized, he concluded that the bird was rarely imposed upon. His con- 

 clusion is upheld by the fact that just one other observer has reported 



