Today, these fish-eating raptors are considered to be one of the Chesapeake Bay’s most iconic creatures, easily spotted between March and August nesting on channel markers, highway overpass signs, dead trees and artificial nesting platforms.
“They’re part of our Chesapeake Bay heritage. It’s a rite of spring to see them return to the Bay,” Jack Cover, National Aquarium General Curator.
Locals hold a special place in their hearts for this species for good reason: They nearly lost it. Osprey numbers crashed from the 1950s through the 1970s, wiping out 90 percent of the New England population.
It’s a comeback story. And it all started with one man: Dr. Paul Muller.
Muller changed the world—for good and for bad—in 1939 when he discovered that dichlorodiphenyltrichloroethane, or DDT, was surprisingly effective in killing mosquitoes and other injurious insects.
DDT was the best solution anyone could have hoped for. It could wipe out nearly every type of harmful insect without hurting humans or other mammals, and one spray lasted a long time. The best part: It was cheap.
As humans reaped the benefits of DDT, something sinister was happening in the food chain. DDT was being absorbed deep into the ground, and stormwater runoff was delivering it straight into waterways. Worms were consuming the chemical as they fed on nutrients in the soil, and small animals were absorbing it from lakes and streams. These creatures were then eaten by larger animals, which were eaten by even larger animals and so on.
The problem here lies in the fact that DDT doesn’t naturally pass through the bodies of fish, birds and mammals. It remains in their fatty tissue. Thus, the more these animals consume, the more DDT builds up in their bodies.
Numbers of various bird species seemed to be dropping, including the osprey. Also known as a fish hawk, the osprey is one of the most wide-ranging species of bird, inhabiting every continent except Antarctica. The best place to find one, however, is the Chesapeake Bay, which hosts the world’s largest-known concentration of nesting ospreys—nearly 2,000 pairs.
“To survive, [the osprey] has to have an abundance of fish near the surface. And when you think of the Chesapeake Bay, it’s really the nursery area for a lot of fish species,” Cover explains. “It’s like the Grand Central Station for fish coming in from the ocean, fish leaving the Bay for the ocean, and a lot of it happens near the surface.”
Because of its widespread distribution, its position at the top of the food chain (it practically has no predators) and its ability to bioaccumulate contaminants, the osprey is an indicator species—meaning, if something fishy is going on with our fish or the ecosystem in general, ospreys will clue us in.
The U.S. osprey was eventually listed in the Redbook “Rare and Endangered Fish and Wildlife of the United States,” and the U.S. Fish and Wildlife Service classified it as “status undetermined.” Canada listed the species as “endangered.”
In the mid-1970s, close to a decade after the publication of Rachel Carson’s “Silent Spring,” the EPA banned the use of DDT in the United States, and other countries followed suit.
To boost the osprey’s recovery, individuals coordinated efforts to build artificial nesting platforms for them. These structures provided ideal replacements for the trees lost through shoreline development, and ospreys quickly adapted to them.
By 1973, nearly two-thirds of Chesapeake Bay ospreys were nesting on artificial structures like duck blinds, channel markers and manmade nesting platforms.
The rest is history. Osprey populations slowly began their recovery, growing by about 2.5 percent each year. The number of breeding pairs in the United States rose from 8,000 in 1981 to 14,246 in 1994. Other species previously threatened by DDT, such as the bald eagle and peregrine falcon, experienced similar growth.
Today, ospreys boast a global breeding population of around 500,000. Their story is proof that people can make a difference.