College study claims high osprey chick death rate related to menhaden harvesting

A female osprey attempts to feed a dead chick in an Eastern Shore nest. It was the last of three chicks to die after more than 38 hours without food.

By Linda Cicoira

The number of osprey chicks recorded recently in the Chesapeake Bay area by researchers at William & Mary’s Center for Conservation Biology is lower than in the 1970s at the height of the DDT era when the widely-used pesticides suppressed hatching.

The cause for the low rates now is starvation.

In the 1970s, osprey’s eggs were affected, said Director Bryan Watts. “Now, chicks are being hatched but often starve. Osprey eat a range of fish including anchovies, sardines, and herring. But their biggest source of food is the tiny but nutrient-dense menhaden,” Watts said.

The researchers believe the decline is due to the increasing scarcity of menhaden tied to overharvesting.

Watts said the decrease has occurred “for at least 15 years or so. But it does seem to be getting worse in that more and more nests are failing.” Only about one in 10 osprey pairs are successful in producing offspring, a number that won’t sustain birds.

Watts acknowledged that the findings open a “political minefield” of regulating the menhaden harvest in Virginia.

Watts wants a policy that “protects the ecosystem first and industry second. Osprey don’t have a political or economic agenda here. They’re just trying to do their thing,” he said. “They’re sort of the collateral damage to the politics.”

Other factors can affect osprey numbers, such as predators and weather, he said. But the researchers believe the connection they make is well-documented. In 2021, the group experimented with supplementing some nests with more menhaden and found that it lowered starving rates.