Background
Bald Eagles (Haliaeetus leucocephalus) were once fairly common breeders across North America. The Chesapeake Bay watershed has long been a major breeding area for Bald Eagles, and it is estimated that about 3,000 pairs once bred there. However, due to poaching, habitat destruction and the use of DDT and other pesticides, Bald Eagle populations declined drastically throughout their range, including in the Chesapeake Bay. By 1977, there were only 72 breeding pairs in the entire Chesapeake Bay watershed. With the banning of DDT in 1972, and the listing of Bald Eagles as an endangered species under the Endangered Species Act in 1976, the number of nesting pairs in the Chesapeake Bay has steadily increased. By 2001, there were 618 breeding pairs in the Maryland, Virginia, Pennsylvania, and Washington DC portions of the Chesapeake Bay watershed, and the species has been downlisted to "threatened". However, the long-term success of Bald Eagles in the Chesapeake Bay depends on the protection of mature forested coastal areas, which eagles need for nesting, perching and roosting. Coastal areas are undergoing rapid development, and if large blocks of forested areas along the coast are not protected, the Bald Eagles will once again begin to decline in the Chesapeake Bay.

Juvenile Bald Eagles wander over relatively large distances during their first few years, and little is known about their habitat use patterns in the Chesapeake Bay watershed. As Bald Eagle populations in the watershed are increasing, and the amount of mature coastal forest is decreasing, it is important for scientists to understand which habitats young eagles are using so that they may develop management plans to protect these areas. Through satellite telemetry, scientists can gather detailed, long-term data on the habitat use patterns of juvenile Bald Eagles in the Chesapeake Bay watershed.

Methods
Five Bald Eagles, one adult and four juveniles, were rescued from a silt pit near the Potomac River in Charles County, Maryland in early May 2002. After being treated at the Baltimore Zoo, Earthspan scientists placed satellite transmitters on the four juveniles, in cooperation with the Maryland Department of Natural Resources. The transmitters included one solar-powered transmitter, which can last indefinitely, and three battery-powered transmitters, which last about 2 years. The solar powered transmitter has an on/off cycle of 6 hours on and 14 hours off, and the other transmitters have a cycle of 8 hours on and 44 hours off. The birds were released on May 27, 2002 at Sandy Point State Park on the Chesapeake Bay. To see an updated map showing the movements of the four juvenile Bald Eagles, click here.