Tuesday, August 4, 2009
Exhibit Hall NE & SE, Albuquerque Convention Center
Roger J. Masse and Kevina Vulinec, Agriculture and Natural Resources, Delaware State University, Dover, DE
Background/Question/Methods Declines of neotropical migrant songbirds are well documented across the United States. In the East, 45% of forest breeding neotropical migrants showed significant declines from 1978-1987; many of which continue. Consequently, the conservation value of remaining riparian forests for breeding birds needs investigation, especially in agriculturally-dominated landscapes such as Delaware. Determining the conservation value of these forests for particular species may often be a first step in preservation or restoration efforts, and measuring density and productivity of target species may be important to infer habitat quality. Our objectives were to both compare overall avian diversity and the quality of Wood Thrush habitat in riparian forest fragments in north-central Delaware. We selected three riparian forest sites of similar size and conducted five 10-minute point counts in each during June-July of 2008. We established transects in each forest and estimated Wood Thrush density and productivity using the spot-mapping procedure and a reproductive index. We analyzed point count data for species richness using the program ComDyn4 and Wood Thrush productivity using the Mann-Whitney U-test.
Results/Conclusions
An estimated 32 and 29 species occurred in the Steamboat and Finis forests, respectively, while an estimated 16 species occurred in the Upper Blackbird Creek (UBC) forest. No Wood Thrush territories were documented in the Steamboat forest. Wood Thrush density was 2.4 males per 10-ha in the UBC forest and 13.2 males per 10-ha in the Finis forest. Despite higher density, Wood Thrush productivity was not significantly greater in the Finis forest compared to the UBC forest. Species richness may be reduced by invasive plants like multiflora rose as the degree of rose invasion is greatest in the UBC forest. However, future research coinciding with rose removal and control measures is needed to infer such a relationship. Wood Thrush habitat quality appears greatest in the Finis forest. While habitat quality varied among forests, some small forest fragments likley provide higher quality habitat relative to others in the region. Identifying these areas is important for the conservation of this species of concern. Once identified, these areas can be protected or used for future research to examine the relationships between habitat structure and quality.
