By Don Lyman
The Boston Globe, June 15, 2020
A breeze blows across a salt marsh in Gloucester and stirs the feathers of a female osprey sitting on a large nest made of sticks atop a 10-foot-tall wooden nesting platform. Her mate is sitting on a post overlooking a salt pool not far away, feeding on a fish he’s caught.
The female, named Annie, stands up and hops onto the edge of the nest, revealing two recently hatched chicks and a large unhatched brown speckled egg. Her mate, Squam, spreads his wings and flies up to the nest, carrying a 2-foot-long striped bass in his talons, which he drops in front of Annie.
She doesn’t waste any time digging into her lunch, ripping off pieces of the fish with her sharp, curved bill, and scarfing them down. After she’s satisfied her hunger Annie begins picking tiny pieces of the fish off and feeding them to her chicks, both of whom are begging for food with their little bills open wide.
“Male ospreys do most of the hunting — catching fish for females, chicks, and themselves,” said David Rimmer, director of land stewardship and manager of the osprey program for Greenbelt, a land conservation organization that protects farmland, wildlife habitat, and scenic landscapes across Essex County.
I wasn’t watching this wildlife scene sitting in the salt marsh with a pair of binoculars. I was 30 miles away looking at my computer screen. This live view of these beautiful hawks was brought to me courtesy of Greenbelt’s OspreyCam, a video camera overlooking the osprey’s nest.
Rimmer said Greenbelt’s osprey program was established in 2010 with four main areas of focus: management, monitoring, research, and outreach/education. The OspreyCam and website, ecga.org/Osprey-Cam, help educate people and gives them a chance to be exposed to ospreys.
The first Greenbelt OspreyCam was installed in 2013, next to a nesting platform at the Cox Reservation in Essex, where Greenbelt’s headquarters is located, said Rimmer. A pair of ospreys named Allyn and Ethel built a nest there a couple years earlier, but the ospreys left the Cox Reservation in 2015. In 2019 Greenbelt moved the solar-powered OspreyCam to Annie and Squam’s nest site behind the Lobsta Land restaurant in Gloucester.
The OspreyCam has always been popular, Rimmer said, but this year even more so because of the pandemic.
“People are housebound and trying to find things to occupy their time,” said Rimmer. “It’s been a really busy year so far.”
The management component of the osprey program mainly involves installing and maintaining nesting platforms, Rimmer explained.
Osprey populations in the United States declined significantly from the 1950s to the early 1970s, said Rimmer, mainly due to heavy use of pesticides like DDT, which caused weak egg shells and subsequent nesting failures. Once DDT was banned in the United States in 1972, osprey numbers began to rebound across North America, including Massachusetts.
But osprey recovery in Essex County lagged behind other areas of the state, according to Rimmer, possibly because of coastal development and lack of large trees for nesting.
In 1985 there was only one nesting pair of ospreys in Essex County, on a man-made platform. As more nesting platforms were built, the number of ospreys gradually increased. By 2005 there were eight pairs of ospreys nesting in Essex County, said Rimmer.
Greenbelt erected its first osprey nesting platform in 2008.
“Ospreys need a lot of help,” said Rimmer. “They weren’t finding good trees to nest in. Wherever you find osprey populations there’s been a lot of assistance with nesting platforms. In 2019 there were 49 nesting pairs in Essex County, East Boston, and Revere, and this year we expect to go over 50.”
Ospreys have an affinity for nesting on man-made structures, such as utility poles and chimneys, said Rimmer. There are three nesting pairs on channel markers in Lynn Harbor, and one osprey pair is nesting on a light tower in the parking lot of the former Wonderland Dog Track in Revere.
The nesting season for ospreys in Massachusetts usually lasts from April to August, Rimmer said. They typically lay three eggs, which take about 40 days to hatch. It takes another 40 days for the chicks to fledge.
With a wingspan of about 6 feet and weighing up to 3 pounds, ospreys are one of the biggest birds of prey, Rimmer said.
Also known as fish hawks, ospreys are the only raptors that feed almost exclusively on fish. Types of fish they eat include smallmouth bass and perch in fresh water, and herring, striped bass, mackerel, menhaden, and bluefish in salt water.
Surprisingly, they even eat flounder, a bottom dwelling flatfish that would seem hard to catch.
“They catch flounder at low tide when the water is only 6 inches to a foot deep,” said Rimmer. “It’s one of their staples.”
When catching fish ospreys dive into the water feet first, with their head tucked between their feet.
“Their feet and head enter the water at the same time,” said Rimmer. “They need to be able to see where they’re going and catch fish with their feet.”
Ospreys can’t remain in Massachusetts during the winter, Rimmer said, because not as many fish are here and because the water often freezes.
Greenbelt puts leg bands on 20 to 30 osprey chicks a year to help track their migrations.
Aside from great horned owls that sometimes prey on osprey chicks or even on adult ospreys in their nests at night, ospreys have few natural predators, said Rimmer. But they do face other threats.
Ospreys live about 15 to 20 years in the wild, Rimmer said. But there’s only a 40 percent chance that a newly fledged osprey will live through its first year because they have to navigate a new migration route, which involves finding food, avoiding hurricanes, etc. They become more efficient as they get older.
“The biggest threat,” said Rimmer, “would be if we humans stopped helping them.”
Comentários