HOST RELATIONS OF PARASITIC COWBIRDS 91 



Rowley and Orr (1960). On June 13, 1958, in a pine-oak forest three 

 miles east of Cuernavaca, Morelos, Mexico, Rowley found a nest 

 containing 3 eggs of the vireo (nominate race) and 1 of the parasite; 

 the eggs are now in the collection of the California Academy of 

 Sciences. 



Black-and-white Warbler 



Mniotilta varia (Linnaeus) 



The black-and-white warbler is a somewhat uncommon victim of 

 the brown-headed cowbird; only 38 instances have come to my notice. 

 The cases range from Alberta eastward to Ontario and Quebec, and 

 southward to Massachusetts, Rhode Island, Connecticut, New York, 

 Pennsylvania, Ohio, Illinois, Michigan, Missouri, Iowa, Kansas, and 

 South Carolina (with one instance). There is also only one record 

 from Alberta — a parasitized nest found there by T. E. RandaU and 

 involving the northwestern race of the parasite, M.a. artemisiae. All 

 the other records refer to the eastern race M.a. ater. Although in 

 most places this warbler is imposed upon rather infrequently by the 

 parasite, it should be noted that Kells (1902, p. 230) considered it to 

 be seriously molested at Listowell in south-central Ontario. In 

 southern Quebec, Terrill (1961, p. 6) reported four cases of parasitism 

 out of 14 nests that were observed. Although most of the recorded 

 instances involve cowbird eggs in nests of this bird, Morden's observa- 

 tions (1884, pp. 193-194) show that the black-and-white warbler 

 may, and does, rear the young parasites. He found two well- 

 nourished young cowbirds in a nest and underneath them there were 

 an addled cowbird egg and two young warblers nearly dead from 

 starvation or suffocation. As many as 5 cowbird eggs, together with 

 3 eggs of the warbler, have been reported from a single nest (Trippe, 

 1868, p. 171-172); Byers (1950) found 8 cowbird eggs in a nest, with 

 2 eggs of the warbler, near Half Moon Lake, Michigan. The South 

 CaroUna record, a set of 3 eggs of the warbler and 1 of the cowbird, 

 taken in Anderson County, May 1, 1893, by C. B. Crayton and now 

 in the Bent collection in the United States National Museum, is of 

 interest as a far southeastern record. 



Prothonotary Warbler 



Protonotaria citrea (Boddaert) 



Because of its habit of nesting in holes — frequently in dead trees in 

 swampy places and even in standing water — to find this species often 

 parasitized by the cowbird is somewhat surprising. No less than 54 

 definite records have come to my notice from Ontario in Canada 

 and from Alabama, Arkansas, Delaware, Illinois, Indiana, Iowa, 

 Minnesota, Missouri, New Jersey, Ohio, Oklahoma, and Virginia in 

 the United States. AU of these cases involve the eastern, nominate 



