The circle of life may be at work at Vermont's Lake Arrowhead, where ospreys failed this summer to produce fledglings for the first time in more than a decade, most likely due to a fisher or other predator.
Despite a record-setting six nests at Lake Arrowhead, ospreys failed to produce any fledglings at the manmade lake for the first time since 1998.
Five pairs of ospreys were sitting on eggs early this spring, but one nest was abandoned after a few weeks. A sixth nest appeared a short time later, presumably built by the pair that abandoned their initial nest, but none of the birds have been successful.
A lone egg, covered in debris, remained in the abandoned nest weeks after the ospreys moved on. The nest was close to the lake's boat access and a train trestle that skirts the eastern end of the lake.
"My guess is that these were young birds building their first nest, so this is a learning process," Vermont Fish and Wildlife biologist John Gobeille said. "I don't know why they chose this site, because there are plenty of better nest sites nearby. It is probably due to the birds' preference to nest over water."
Many of the other nest failures were at locations that have previously produced chicks that grew into fledglings.
"Given that virtually all of the other nests in the region were successful, I think a predator is probably is to blame for most of the failures at Lake Arrowhead," Gobeille said. "A fisher or a great horned owl may have found this to be a perfect place to hunt this summer."
Lake Arrowhead became famous for its ospreys thanks to Meeri Zetterstrom, a wildlife advocate who convinced the state and Central Vermont Public Service to put up nesting platforms for the birds in the late 1980s. After a decade of work to provide suitable sites and educate Vermonters about the birds, the first chick hatched and fledged in 1998. At least once osprey chick has been successfully fledged at the lake every year since, until this year.
CVPS spokesman Steve Costello, who worked with Zetterstrom, Gobeille and other state officials over the years, said the failed nests provided a reminder of how the natural world is filled with interdependancies.
Gobeille and Costello plan to add a new platform at Lake Arrowhead this fall, and will look at ways to install new predator shields on existing nest platforms in case a fisher is responsible for the failures.
"Given their rebound from near extinction, we do want to provide the ospreys an opportunity to thrive at the lake," Costello said. "It was a disappointing season, but if predation was the cause of most of the failures, as it appears to be, it's important to remember that every species has got to eat - even species that see ospreys as a meal ticket."