Warbling Vireo

Vireo gilvus (Vieillot)

While the warbling vireo, as a species, is well known as a frequent victim of the brown-headed cowbird, its western population, forming the race V. gilvus leucopolius, has been so reported in print only twice (Friedmann, 1963:90). Six more instances may be added: a parasitized set of eggs taken in Tuolumne County, California, 6 June 1939, now in the collections of the Western Foundation; a statement (Crowell and Nehls, 1973:911) of this vireo's being parasitized in the Victoria area, Vancouver Island; and 4 records from Saskatchewan and Manitoba in the Prairie Nest Records files at the Manitoba Museum. In Ontario the incidence of cowbird parasitism on this vireo (V. g. gilvus) is unusually low: 1 such nest out of a total of 62, or 1.6 percent (Peck, 1975).

BLACK-AND-WHITE WARBLER