A high incidence of brown-headed cowbird parasitism of willow flycatchers
Brown-headed Cowbirds (Molothrus ater) parasitize both Willow (Empidonax traillii) and Alder (E. alnorum) flycatchers (Friedmann et al. 1977, Friedmann and Kiff 1985). These two flycatchers were considered a single species until 1973 (AOU 1973), which has masked information about the frequency with which each is parasitized. Whereas several studies of the superspecies (Traill's Flycatcher) have focused on or included details of cowbird parasitism, most were of eastern populations, and most reported frequencies of parasitism ≤21% (Hicks 1934, Berger 1951, Berger and Parmalee 1952, Walkinshaw 1966, Holcomb 1972). Friedmann et al. (1977:13) suggested that western populations (Willow Flycatchers) are parasitized only about half as much (ca. 10%) as eastern populations (Traill's Flycatcher superspecies). This note described a high rate of cowbird parasitism within a population of Willow Flycatchers in northcentral Colorado. We include details of responses to parasitism and host vs. cowbird fledgling success.
Citation Information
Publication Year | 1988 |
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Title | A high incidence of brown-headed cowbird parasitism of willow flycatchers |
DOI | 10.2307/1368461 |
Authors | James A. Sedgwick, Fritz L. Knopf |
Publication Type | Article |
Publication Subtype | Journal Article |
Series Title | The Condor |
Index ID | 70122140 |
Record Source | USGS Publications Warehouse |