Predation of Songbird Nests Differs by Predator and between Field and Forest Habitats

Abstract

Our understanding of factors affecting nest predation and ability to mitigate high nest predation rates is hampered by a lack of information on the importance of various nest predator species in different habitats and landscapes. We identified predators of songbird nests in old-field and forest habitats in central Missouri, USA, with miniature video cameras. We used an information-theoretic approach to evaluate support for hypotheses that the importance of predator species varied among habitats and nest stage. We monitored 165 nests with cameras and 272 nests without cameras during 1997-1999, and identified predators at 61 of 74 depredated nests monitored by cameras. Model selection indicated the most support for a model with seperate rates for predation by birds, mammels, and snakes in field and forest habitats. Predation by snakes was greater than predation by mammels and birds in old fields; predation by mammels (mostly rccoons [Procyon lotor]) was greater than by snakes and birds in forest. We found little support for the hypothesis that monitoring nests with cameras effects predation. Nests could not be assigned reliably to a predator group based on condition of the nest. We believe that knowledge of the identity and abundance of dominant predators in a habitat or landscape is neccessary to target conservation efforts to reduce nest predation or to interpret results of research on factors affecting nest success.