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Reproductive success of Acadian Flycatchers in the Blue Ridge Mountains of Virginia

Fauth, Peter T., Cabe, Paul R.
Journal of field ornithology 2005 v.76 no.2 pp. 150-157
Molothrus ater, adults, birds, breeding season, clearcutting, fecundity, females, fledglings, forests, habitat fragmentation, habitats, landscapes, migratory behavior, nesting, nests, parasitism, predation, summer, survival rate, tropics, Blue Ridge Mountain region, Virginia
Conservation strategies for Neotropical migratory birds have emphasized identification and preservation of habitats in which populations are reproducing above replacement rates. In 2000–2001, we monitored 141 Acadian Flycatcher (Empidonax virescens) nests in the extensively forested Blue Ridge Mountains in Virginia to assess the site's potential to host “source” populations of this common species. Our estimates of reproductive success, unlike most studies, incorporated the nesting behavior of marked females followed throughout the breeding season. Despite the presence of Brown-headed Cowbirds (Molothrus ater) in a nearby 15-y-old clearcut and in open areas of a summer camp, we found no parasitized nests. Overall, the predation rate was 41%, 2.5 fledglings were produced per successful nesting attempt, and seasonal fecundity approached two female fledglings per adult female per season. Given return rates (minimum survival rates) of 52% at our study site, our measured levels of reproductive success are sufficient to classify the Blue Ridge Mountains as a potential “source” for Acadian Flycatchers. Our data contrast sharply with those collected from landscapes with high levels of forest fragmentation in the midwestern and southeastern U.S., where even relatively large patches of forest appear to host “sink” populations of Acadian Flycatchers.