Its decline was further hastened by the discovery in 1939 of the insecticide properties of a chemical called Dichloro-Diphenyl-Trichloroethane, better known as DDT. Initially thought to be the safest pesticide ever produced, it was widely used until the work of Rachel Carson and others sounded the alarm about its toxicity to aquatic organisms and its devastating impacts on bird reproduction. The latter was felt most keenly in birds of prey like pelicans, peregrine falcons, and bald eagles, because residues of DDT were stored in fat and nearly impossible to eliminate from a creature’s system, leading it to accumulate at high levels in animals high up the food chain.
After reaching a low of 417 nesting pairs within the lower 48 states in 1963, intensive recovery efforts, including a ban on most uses of DDT in 1972, helped the population rebound to 9,789 breeding pairs by 2007. At that point, the bald eagle was declared to be recovered from the threat of extinction, and “delisted” from the Endangered Species Act. While recovery has been dramatic nationwide, perhaps nowhere has the bald eagle made as spectacular a comeback as here in Virginia. Only four states in the nation have more bald eagle pairs than we have: Washington and Alaska, which have long been a population stronghold for the species (the bald eagle was never ESA-listed in AK), Minnesota, with its vast areas of sparsely-populated Northwoods and thousands of lakes and miles of streams, and Florida.
Given that our numbers are concentrated in a fairly small geographic area along the major Chesapeake tributaries of the Potomac, Rappahannock, and James rivers, we can legitimately boast of the highest concentration of bald eagles anywhere outside of Alaska.
The Center for Conservation Biology, based at The College of William and Mary, has conducted
bald eagle nest surveys since the 1950s, and their numbers tell the story: six nests in Virginia in 1956, and 34 in 1962, but with only three confirmed as successfully producing young. Fast forward to 2011, the last year that the CCB surveyed the entire state: the result was an astonishing 730 breeding pairs and 980 chicks. The Center now focuses its survey efforts mainly on the James and Rappahannock Rivers, and they report that this year the Rappahannock had 199 pairs that produced 278 chicks. With another 200+ pairs confirmed in the James Basin, the population in the state is probably now somewhere around 800-850 breeding pairs.
Given that the estimates of the “pristine Chesapeake” eagle population range from 1500-3000 pairs (split roughly evenly between Virginia and Maryland), it is not a stretch to say that we may have about as many eagles today as when John Smith explored the region in 1607. Rachel Carson, author of the seminal “Silent Spring,” who once despaired of the imminent extinction of our national symbol, would be proud.
Carson, Rachel. Silent Spring. Houghton-Mifflin, Boston: 1962.
Center for Conservation Biology at College of William and Mary:
Historic Bald Eagle Population. http://www.ccbbirds.org/what-we-do/research/species-of-concern/virginia-eagles/status-in-virginia/
Summary of Annual Survey. http://www.ccbbirds.org/what-we-do/research/species-of-concern/virginia-eagles/annual-survey/
The James River: Comeback Central for Eagles.
Active Map of Eagle Nests. http://www.ccbbirds.org/maps/#eagles
US Fish & Wildlife Service. Bald Eagle Recovery page. http://www.fws.gov/midwest///eagle/recovery/qandas.html
US Fish and Wildlife Service. DDT and Other Organochlorine Insecticides. http://www.fws.gov/contaminants/Info/DDT.html
By Aimee Delach, FOR Volunteer