Sherry Pettyjohn, program chair, introduced Kevin Goff, a graduate of William and Mary with a master’s degree from the Virginia Institute of Marine Science (VIMS). He taught at Essex High School for several years and then taught at the Chesapeake Bay Governor’s School for Marine Science. He is currently on sabbatical finishing a marine science curriculum and textbook for high school students.

His presentation at the February 27 general meeting was entitled “Bald Eagles and Osprey of the Lower Chesapeake Bay, or Perils of Feeding High on the Food Chain.”

The osprey, Pandion haliaetus, whose scientific name means, “salt eagle,” is the only bird to feed exclusively on live fish. It does not eat carrion or other prey. The osprey is a raptor that is found throughout the world; however, the Chesapeake Bay hosts the largest known breeding concentration.

Large birds with five-foot wingspans, they mate for life. They leave the Chesapeake Bay area in the fall and return in the spring to nest.

The bald eagle, Haliaetus leucocophalus, whose Latin name means, “white-headed salt eagle” is a huge bird with a wingspan of seven feet. Unlike osprey, bald eagles will eat carrion and other prey in addition to fish. There are about 400 pairs that make up the resident breeding population in the Chesapeake Bay. There are also two migrant populations in the Chesapeake Bay area, one of which migrates to Canada in winter and the other which migrates to Florida in summer.

Bald eagles also mate for life. They breed in late winter in huge nests. Unlike the osprey, they do not tolerate human activity well.

It is relatively easy to tell the two species apart. Eagles have straight broad wings. An osprey’s wings crook at the “wrist” and have a dark spot.

Bald eagles need large hunting grounds to provide enough food. They defend their territories through fighting, using their talons.

Mr. Goff described the food chain relative to these raptors: phytoplankton are eaten by zooplankton, which are eaten by fish, which are consumed by eagles and osprey. He discussed mechanisms whereby substances such as DDT are concentrated as a species is higher on the food chain.

Ospreys and eagles are somewhat competitive for the same resources. There is also competition between people and these birds for similar resources. The Rappahannock River, where so many eagles make their home, is relatively pristine but is threatened by development. -