Meeting Abstract

24.3  Monday, Jan. 4  When is Success not Success? When it’s Songbird Nesting Success STREBY, Henry/M*; ANDERSEN, David/E; Minnesota Cooperative Fish and Wildlife Research Unit; Minnesota Cooperative Fish and Wildlife Research Unit streb006@umn.edu

Estimates of nesting success have long been used as a proxy for reproductive success in songbird populations. These estimates have been used to monitor populations across multiple temporal and spatial scales, index habitat quality, and model source-sink population dynamics. Despite a growing body of evidence that the post-fledging period is a time of high mortality for many songbird species, this period is usually unstudied and often included in population models as an ambiguous constant. During 2007 and 2008 we studied reproductive success of a population of Ovenbirds in the Chippewa National Forest in north-central Minnesota. We monitored 234 active Ovenbird nests and tracked 110 fledglings from successful nests using radio telemetry. Although nesting success was twice as high in 2008 as in 2007, the opposite was true for post-fledging survival, resulting in nearly identical estimates of full season reproductive success. Our results suggest that survival may be highly variable during the dependent post-fledging period, which has implications for using nesting success as a proxy for reproductive success in a variety of contexts.