The Chesapeake Bay is considered the nation’s largest breeding ground for osprey. Osprey chicks usually occupy just about every nest stand built by homeowners, even one at the Virginia Institute of Marine Science, and on some navigational markers.
But not this year.
There’s a growing concern among the bird’s admirers and scientists over a steep decline in chicks. Scientists have been monitoring osprey nests throughout the bay.
"We have been seeing a lot of nest failures due to starvation," says Bryan Watts.
Watts is director of the Center for Conservation Biology at the College of William & Mary. Wrapping up field work, he and Biologist Bart Paxton take their small skiff out on the Rappahannock River near Urbanna. They check on some of the 46 nests that had fledglings. Only four were successful.
It’s a snapshot of something wrong.
"So, a number of bird species move with the food. Osprey aren’t like that," Watts notes. "When an osprey pair form a territory, they will come back to that area year after year. Where there’s not enough fish to go around, then the population will come into balance with that and decline."
He’s seeing that decline in southern portions of the bay. And the average number of chicks in a nest has gone from two to one.
"We go to a nest and there may be three young chicks. We come back the next time, there may be two or one, and we come back the next time and there's none. We have seen plenty of dead chicks in the nest. When you handle these chicks, they're emaciated," Watts says.
On a steamy day on the Rappahannock this summer, the water below the boat measures 90 degrees Fahrenheit. As they motor from one nest to another, they pass a tiny school of juvenile menhaden or, as anglers say, “bait balls,” churning and flashing just below the surface.
Menhaden migrate in and out of the Chesapeake Bay. High in nutritious oil, they’re targeted by osprey to fatten chicks. And they are a mainstay of a commercial fleet of ten ships from Reedville, Virginia that catch them here and just outside the bay, and parts of the coast.
Last year, Watts took some heat for saying they were responsible for diminishing the fish stocks.
Osprey chicks have their greatest food demand from mid-May through June. But menhaden are coming into the bay later.
"Last year, the menhaden didn't come in until early June and we had a spike in laying, which is the latest we've ever recorded. They don't do well, the ones that nest late. They're vulnerable to the excessive heats that we get in July and August," according to Watts.
Two days later, in the upper part of the bay, Barnett Rattner and Dan Day, scientists with the U.S. Geological Survey, are with two undergraduate students checking osprey nests along the Chester River near Kent Island, Maryland. This is year two of a collaboration with Watts, adding 100 nests on this river. Last year, it was just the Choptank River.
"In 2024, 80% of the nests either didn't get started or had eggs or young and failed," Rattner says. "The Choptank River in 2025 is no better than it was in 2024."
Rattner’s team also is looking at the species of fish ospreys are catching. Some homeowners with osprey stands have let them put up game cameras. Fish experts will examine tens of thousands of images to pick out those with clearly distinguishable fish.
Like Watts, Rattner is seeing nest failure. But location is important.
"We have pretty fair evidence that what we're seeing at least in parts of the bay is related to food availability. In other parts of the bay, particularly up the tributaries, there really isn't evidence that is a serious problem," Rattner notes. "Depends where you are in the bay where one sees the problems and what is there for the ospreys to capture, to eat and to feed to their young."
The Chester River looks fairly successful. Osprey nests in fresher waters, where birds don’t rely on menhaden, like the upper Potomac in Washington, D.C. seem to do well.
But another osprey survey this summer in New Jersey, shows a high number of nest failures at the coast. They, too, blame the lack of menhaden.
And though more data needs to be collected, one thing scientists agree on, ospreys are telling us something is wrong.
This report, provided by Virginia Public Radio, was made possible with support from the Virginia Education Association.