Pheucticus melanocephalus (Swainson 1827)

Pheucticus melanocephalus (Swainson)

A parasitized nest of the black-headed grosbeak reported from Butte County, California, by Dembosz, Fickett, and Manoles (1972:979) refers to the host race P. melanocephalus maculatus, a subspecies not hitherto recorded as a cowbird victim. A second instance, from San Luis Obispo County, California, 1 May 1937, is in the Lawrence Stevens Collection in the Santa Barbara Museum of Natural History. The cowbirds involved in these 2 cases are of the race M. ater obscurus, a subspecies not previously reported as a parasite on any race of this grosbeak.

The nominate race of the grosbeak has been reported as a cowbird host a number of times in British Columbia (Friedmann, 1971:247), and in Montana, Utah, Colorado, Nebraska, and Kansas (Friedmann, 1963:139). Still, on the whole, the black-headed grosbeak appears to be parasitized much less frequently than the rose-breasted species. In the holdings of the Western Foundation are 271 sets of eggs of P. melanocephalus, none of which are parasitized, while of P. ludovicianus there are 59 sets, 5 of which (8.1 percent) have cowbird eggs.

BLUE GROSBEAK