Photograph by Peter McGowan, USFWS

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Since the mid-1970's the population of Chesapeake Bay ospreys (Pandion haliaetus) has more than doubled (>3000 nesting pairs). However, a survey in 1995-1996 found very few nesting pairs in Regions of Concern in the Chesapeake Bay (2 in the Anacostia River, 16 in Baltimore Harbor, and 5 in the Elizabeth River), and their breeding success is unknown. Because of the contaminant concerns identified in the Regions of Concern, and the small amount of data regarding exposure to these contaminants by Chesapeake fish-eating birds, the Chesapeake Bya Filed Office is conducting the first large-scale ecotoxicological evaluation of ospreys nesting in the Chesapeake Bay in more than 15 years.

This study will is assess contaminant exposure and potential effects on ospreys nesting on navigation markers and other fixed structures within two Regions of Concern (Anacostia River and Baltimore Harbor), and at a reference location (including the South, West and Rhode Rivers). During the spring and summer of 2000, a single egg was collected from each nest and analyzed for organochlorine pesticides, total PCBs and PCB congeners. Blood and feather samples from near fledging young were collected and analyzed for heavy metals, metalloids and trace elements. Nest success (hatching of eggs and fledging of young) and growth rate of nestlings were monitored weekly to determine any relationships between contaminant exposure and reproductive success.

Egg and blood samples have not been analyzed yet, however, preliminary results show that reproductive success within the Anacostia/Potomac River and Baltimore Harbor is lower than the reference site.