Western Kingbird

Tyrannus verticalis Say

This rarely recorded host, originally listed (Friedmann, 1963:49) without a definite case, has since been reported 3 times as a cowbird host. T. S. Smith (1972) found a parasitized nest in York County, Nebraska, in June 1971, from which a young brown-headed cowbird and a young kingbird were fledged. A parasitized set of eggs of this kingbird from Merced County, California, collected by H. R. Eschenburg, 23 May 1936, is now in the Delaware Museum of Natural History; another set, taken in Wasco County, Oregon, 11 June 1933, is in the collection of Oregon State University.

Smith's observation adds the western kingbird to the list of victims known to raise the young of the parasite. The Merced County, California, egg record is the first for the southwestern race of the cowbird (M. ater obscurus).

This species has been designated tentatively as a rejecter. Artificial cowbird eggs were ejected from the 2 nests to which they were added (Rothstein, 1975a). The paucity of observed cases of natural parasitism agrees well with this rejecter behavior of the western kingbird.

GREAT CRESTED FLYCATCHER