Conserve Wildlife Foundation sees unusual year for osprey breeding
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Conserve Wildlife Foundation sees unusual year for osprey breeding

‘TRIPPED’: The Conserve Wildlife Foundation isn’t sure why only 16 of 29 occupied osprey nests surveyed at the Barnegat Bay colony produced young or pairs, while the remaining nest sites produced no eggs or young. (Photos courtesy of Ben Wurst/CWFNJ Senior Wildlife Biologist)

It’s been a strange year for osprey breeding across the state. Ben Wurst, senior wildlife biologist for the Conserve Wildlife Foundation of New Jersey, began noticing this spring that many healthy pairs in our area weren’t breeding — including a pair seen on the organization’s popular osprey camera at Barnegat Light, as well as a familiar pair on the southern tip of Long Beach Island and another on the Mullica River southwest of LBI. Wurst decided to see if this was a more widespread problem.

“We put out a call on social media for osprey nest watchers to report anything strange to us, and we also reported osprey nest activity online through osprey-watch.org,” Wurst explained. “Some people reported seeing the same behavior.

“After hearing similar reports from nest observers, we embarked on an early-season survey of osprey nests in the first week of June to see how widespread this might be,” he added.

CWF examined 29 occupied nests in a colony located in Barnegat Bay, between Barnegat Light and Holgate. Of those 29 nests, 16 were still incubating eggs or had hatched at 2 to 5 days old. The remaining nests contained pairs but no eggs or young. According to Wurst, “Most of these nests in previous years, except for the last two, usually produced at least one or two young, with the occasional nest that failed (meaning no young). It is rare to see so many nests without eggs or young.”

Then he received an email from Bryan Watts, director of the Center for Conservation Biology at the College of William and Mary in Williamsburg, Va. In his message, Watts wrote, “Our season here is unusual, with an unusually high number of pairs not laying at all, those that are doing so are very late compared to previous years, and (there has been) a shift to smaller eggs. The arrival of pairs has been normal, but some did not lay eggs until two to two and a half months after arrival. We have had several eggs laid in the last two weeks, which is very late for us.”

For now, Wurst said, biologists are “puzzled and searching for answers to our questions about why healthy, reproductive ospreys are not reproducing. Is some kind of pollution affecting their reproduction? Is it some unknown pathogen?”

Ospreys, also known as fish hawks, are typically found along the coastline, where they hunt fish from marshes, streams, and bayous. While a lack of food may be a likely cause for the decreased reproduction, there was no shortage of Atlantic menhaden as observed in 2022 and 2023. Daisy and Duke, a pair located at the Barnegat Light osprey camera site, showed no shortage of menhaden, with both catching a good number of them.

“A local bait fisherman has also reported plenty of adult menhaden offshore this year,” Wurst noted. And so scientists remain baffled.

Volunteers conducted additional research to try to figure out why ospreys are not breeding in the expected season after years of steady population growth that began in the mid-1970s, when the New Jersey Department of Fish, Game and Wildlife listed the species as endangered.

Decades ago, before the synthetic insecticide DDT decimated the population, more than 500 osprey nests could be found along the New Jersey coast. By the early 1970s, only about 50 nests remained. DDT in the food chain “caused reproductive failure, and habitat was lost along with an expanding shoreline population that eliminated many trees and increased ground predators,” Conserve Wildlife explained.

In 1968, New Jersey banned the use of DDT, and in 1974, ospreys were listed as endangered. In the meantime, biologists have worked to protect and expand the remaining population.

“By 1986, the osprey population exceeded 100 pairs, prompting the decision to upgrade their status to threatened,” CWF noted. “Since then, Endangered and Nongame Species Program staff have worked to monitor and manage the population, tracking nesting success each year with a core group of volunteers and conducting a population census every three years.

“In 2006, the New Jersey osprey population reached a new post-DDT high of just over 400 active nests, slightly below the estimated historical population of 450 to 500 nests. In 2009, 486 nesting pairs were found,” and last year biologists documented a record 800 occupied nests. The Conserve Wildlife Foundation, along with NJ Fish and Wildlife and volunteers from the NJ Osprey Project, helps manage and protect the species in the state, with most of its work focused on Barnegat Bay, Little Egg Harbor and Great Bay.

Last month, the Murphy administration proposed removing ospreys from the state’s endangered species list, based on findings that populations have recovered to the point that the species’ survival in the state is no longer threatened. As Shawn M. LaTourette, commissioner of the New Jersey Department of Environmental Protection, noted at the time of the announcement, the proposed delisting is contained in a DEP rule proposal published in the New Jersey Register.

The proposed rule makes additions, deletions, and updates to the conservation status of the state’s endangered species list and nongame wildlife list. It also restructures the state’s endangered species list to be consistent with the intent of the legislature.

Under the proposed regulation, ospreys, currently listed as a threatened species in New Jersey, would be reclassified as a stable species. (The DEP will accept public comments on the proposed regulation through Aug. 2. More information is available at dep.nj.gov/rules/notice-of-rule-proposals.)

Given this pending status change, ospreys, Wurst said, will continue to require management — since most of the population nests on artificial nesting platforms — as well as monitoring to see changes in productivity from year to year. The Conserve Wildlife Foundation, he emphasized, “is committed to continuing our grassroots efforts to protect ospreys to ensure their sustainability into the future.”

Learn more about ospreys at conservewildlifenj.org.

— Juliet Kaszas-Hoch

[email protected]