Virginia Ospreys in Trouble?

Nesting pairs of Osprey in 1987 and 2025

Chesapeake Bay Mag, Osprey Pairs Down to Single Digits on Ocean Side of ESVA

Dr. Bryan Watts, Director of the Center for Conservation Biology (CCB) at William & Mary, has released an inventory of active osprey nests along Virginia’s Eastern Shore Seaside. His report’s title tells the ugly story: “Osprey Population along the Seaside of the Delmarva Peninsula has Collapsed.” Where a CCB survey in 1987 recorded 83 pairs, this year’s survey recorded only nine pairs between Fisherman Island and the Chincoteague Causeway.

 

“We’ve been watching them since the 1990s,” Dr. Watts tells us, “ and the loss rate has really ratcheted up in the last few years.” This population collapse is a concern not only for the loss of an iconic, well-loved bird but also for what it says about the condition of this coastal environment that appears otherwise pristine.

Why the failure? Dr. Watts’s careful summary says: “The underlying causes of this population decline are unclear. Although there have been changes in nesting substrates (like duck blinds, dead trees, navigational aids, or nesting platforms) over time, the availability of nesting substrate does not appear to be a primary factor. Suitable structures remain widely available and many substrates that were used for extended periods are now vacant.

“It is possible that bald eagles may have impacted osprey along the seaside. The bald eagle population within the area has more than tripled since the 1980s. However, the density of eagles continues to be a small fraction of that found within the upper tributaries of the Chesapeake Bay where ospreys continue to thrive.”

That's interesting, I was just speculating about that a few days ago. Bald Eagle commonly rob Ospreys of their prey. Ospreys are great fisherman, but at some point, that has to impact the amount of food they can bring home to feed their chicks. And Bald Eagles seem even more efficient at stealing food from Ospreys than Ospreys are at fishing. I don't think I've ever seen an eagle fail to force an Osprey to drop it's fish.

He goes on to report, “The most likely cause of the decline is prey availability. However, no osprey diet studies have ever been conducted within this site, and we know very little about trends in fish availability. During the 1970s and 1980s, the highest density of nesting pairs was skewed to the southern portion of the area around Fisherman and Mockhorn Islands. These birds could be observed flying out to the mouth of the Chesapeake to forage. Pairs have declined by more than 90% within this portion of the study area.”

When looking for causes, questions arise about the availability of menhaden for ospreys to eat in the “southern portion of the area around Fisherman and Mockhorn Islands.” Some believe menhaden industry giant Omega Protein is competing with the ospreys for their food.

I'm beginning to believe the Osprey population in our Mid Bay region is following the same trajectory, just a few years later.  Our local Osprey population seems to have thinned. I only saw a single Osprey plying the waters off our beach today. There were plenty of peanut sized (2-3 inch) Menhaden dead on the beach, it doesn't seem like lack of them is the problem. 

So, Stripped Bass are in trouble, crabs are in trouble, and the Ospreys are in trouble. I'm sure satisfied the with $25 billion or so we've dumped into the Bay's bureaucracy in the last 30 years.