A pair of bald eagles rest after eating a fish. Photo by Bill Mish, submitted for the 2024 Maryland DNR Photo Contest
For 18 years, Glenn Therres watched the recovery of Maryland’s bald eagles from the window of a four-seater plane.
The long-time bald eagle biologist for the Maryland Department of Natural Resources, Therres had counted nests for the department’s annual bald eagle survey since 1985, when there were only 62 breeding pairs in the state. Every year, he would cross the watery parts of Maryland from 200 feet above in a Cessna, scanning the treetops for bald eagle nests. A few months later, he would come back to count the nestlings.
“Every year we would find additional nests and map the new locations,” said Therres, who retired from DNR in 2021.
For a while, a few more active nests would appear each year, but by 1990 they found 123 breeding pairs, and 200 only six years later.
“In the early days, we flew three days, then another three [for the young eagles],” he said. “By the end, we were flying nine or 10 days each survey period just to cover all the nests.”
By 2004, DNR found 390 breeding pairs of bald eagles in Maryland. Therres ended the department’s survey after that—the species had well surpassed its recovery goals in the Chesapeake Bay region. In 2025, the Maryland Bird Conservation Partnership estimates there are over 1,400 breeding pairs in Maryland.
It was a long way to come for a bird of prey that had struggled for decades in the state and throughout the country. Across much of their range, bald eagles had fallen to near-extinction levels due to the effects of pesticides, as well as other factors like habitat loss and illegal shooting. In 1963, only 417 nesting pairs had been documented in the lower 48 states.
A pair lives near my house… they often perch in our trees… very cool!
We have a pair here in ocean pines – wonderful to see.