Spatio-temporal patterns of landbird migration on the lower Delmarva Peninsula (Interim)
Abstract
Reported declines of neotropical migratory songbird populations have drawn the attention of the scientific community and the general public. While researchers and conservationists have focused their energies on understanding the behavioral and ecological dynamics of these populations during the breeding and wintering season, migration ecology has remained largely neglected. Migration must be endured twice annually and is a particularly stressful event for birds. Comprehensive conservation efforts on behalf of migratory birds must include this critical phase of life if they are to succeed in protecting whole populations. The two-year Northampton Migratory Bird Project (NMBP) was initiated under Northampton County's Special Area Management Plan (SAMP) to provide this rural, coastal county with sound scientific data to guide the development of enforceable policies that will protect and enhance migratory songbird habitat. Conserving migratory birds and their habitat in lower Northampton County will serve to generate the basis of a burgeoning nature tourism industry, help to protect water quality and moderate secondary impacts of coastal development. Results from the first season of the study show some strong spatial and temporal patterns. In summary, our data indicate: 1. Long-distance migrants are most abundant during the first half of the migratory period while short -distance migrants are most abundant during the last half of the season. 2. Bird activity was greater in the morning compared to the afternoon. 3 . If birds spatially redistribute during the course of a day, they do so very early in the morning. 4. Many long- and short-distance migrants concentrate along the bayside and near the tip of the peninsula. Resident species tend to be least abundant near the peninsula tip. 5. In general, there is no clear relationship between bird abundance and patch size. 6. The majority of birds from both migrant groups were more abundant close to the forest edge than in the interior. 7. Most species overutilized plots with relatively high vegetation density. 8. Individual species were associated with particular vertical strata within the forest. The vertical distribution of species is in general agreement with associations known for the breeding and wintering seasons. The results of the first year provide a critical step toward policy development and land use planning for the protection of migratory songbirds and their habitat in Northampton County, Virginia.
