Raptor trapping at Wise Point Station: Year 2003 report
Large numbers of diurnal raptors from breeding populations across northern latitudes migrate south along the Atlantic flyway to reach winter destinations from southeastern North America to southern South America. Many of these birds become concentrated within geographic bottlenecks where they rest and forage. Each fall since 1978, staff, students, and associates of the Center for Conservation Biology at the College of William and Mary have trapped diurnal raptors near the tip of the Lower Delmarva Peninsula. The research objectives of this project continue to be 1) to monitor trends in the migration of several raptor species, 2) to learn more about the natural history of migratory raptors, and 3) to add to our understanding of migratory movements and pathways. During the fall of 2003, the Wise Point Station was operated on 52 days between 9 September and 23 November for a total of 359 hours. A combination of mist nets, bow nets, and dho-gaza nets were used in conjunction with lure birds to trap migrating raptors. A total of 516 raptors of seven species was banded resulting in an overall capture rate of 1.4 birds/operation hr. The project has recorded lower overall capture rates in only 2 of the previous 15 years. The 2003 season continued a downward trend in overall capture rate. Since 1989, capture rate has declined significantly at an average rate of approximately 6%/year. A decline in the capture rate of Sharp-shinned Hawks appears to be solely responsible for the decline in overall rate. The proportion of total captures accounted for by Sharp-shins has declined from more than 60% of total captures in the early 1990’s to less than 30% in recent years. The population-level implications of continued declines in capture rates for Sharp-shinned Hawks within the mid-Atlantic remain unclear. Six birds that were banded at Wise Point during the 2003 season have been recovered elsewhere. This includes 2 Sharp-shinned Hawks, 3 Cooper’s Hawks, and 1 Merlin. Recoveries ranged from Dover Delaware to Marathon Florida. The Merlin was banded on the 8th of October and recovered in Marathon, FL just 6 days later. A total of 19 birds were captured that had been banded previously elsewhere. These included a young, male Peregrine that was color banded in Canada.