They’ve been observed eating Canada geese
on highway medians, soaring over shopping center parking lots, perched in trees
in bustling Providence, and hunting for fish at nearly every large unfrozen lake
in the state. All of which suggests that sightings of bald eagles in the Ocean
State are no longer the rare occurrence that they used to be. In winter, they
have become almost commonplace.
Last
January alone, bird watchers reported seeing bald eagles at Brickyard Pond in
Barrington, Watchaug Pond in Charlestown, Tiogue Lake in Coventry, Stump Pond
in Smithfield, Trustom Pond and the Great Swamp in South Kingstown, the
Pawcatuck River in Westerly, and flying over numerous other locations. As many as nine bald eagles were sighted
together on the Seekonk River, which is now considered the most reliable place
to find the birds in Rhode Island.
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| Bald eagle photo by Peter Green/Providence Raptors |
And
experts say that eagle numbers are expected to climb even higher.
According
to Tom French, the assistant director of the Natural Heritage and Endangered Species Program for the Massachusetts Division of Fisheries and Wildlife, who
has been monitoring bald eagle numbers in New England for more than two
decades, many of the eagles sighted in Rhode Island in winter are year-round
residents, but they are less noticeable during the breeding season.
He
said that Rhode Island has four nesting pairs of eagles, and most of their
young probably stick around the area for a few years before dispersing to find
breeding territories of their own.
“At
our latitude, most adult eagles don’t migrate,” French said. “Rhode Island also
gets some spillover in the winter of eagles from Massachusetts and Connecticut.
“Plus
we have a contingent of eagles from Maine and southern Canada that migrate. How
far they go is questionable – some definitely go as far as Chesapeake Bay – but
many of them only go as far as they have to to find open water,” he added. “So
some of them probably stop along the Rhode Island coast.”
How
many bald eagles spend the winter in Rhode Island is difficult to say, since
some of the birds move around when ponds and lakes freeze.
“The
number you have in winter is not only based on increases from breeding, but
also based on the weather,” French said. “A good winter for eagles in Rhode
Island means it’s probably been a bad winter weather-wise elsewhere. The colder
the winter in the north, the more eagles you’ll have in Rhode Island.”
That’s
what may account for the dearth of bald eagle observations in Rhode Island so
far this winter. Rachel Farrell, a member of the Rhode Island Avian Records Committee, said that reported eagle observations in December have been about
half of what they were last year.
“Perhaps
the eagles have stayed to the north so far this winter,” she said. “We may see
a huge number of reports in January, which is often the case.”
Rhode
Island hasn’t always had significant numbers of eagles in winter, however. Farrell
said that bald eagles were fairly common winter residents in Rhode Island up
until the 1960s, after which they nearly disappeared from the state for 30
years. Only two bald eagles were observed during the annual Christmas Bird Counts between 1962 and 1988.
The
decline, according to both Farrell and French, was caused by the use of the
pesticide DDT, which made its way into lakes and ponds and accumulated in the
tissues of fish. When eagles ate the fish, the toxin caused reproductive
failure, resulting in a precipitous decline of bald eagle populations
throughout the Lower 48 states.
DDT was banned in 1972, but it has
taken a surprisingly long time for the birds to rebound. Ospreys, the
fish-eating hawks that are now common throughout the region, were similarly
affected by DDT, but they recovered their populations much more quickly than
have bald eagles. It took many years of work by wildlife officials, including
Tom French, to relocate eagle chicks from other parts of the country and place
them with “foster parents” at the Quabbin Reservoir in Massachusetts before the
New England eagle population began to grow on its own.
French said that bald eagles have
now recovered in the region and are still experiencing exponential growth.
Eventually that population growth will level off, when the birds are so
abundant that there is no longer enough nesting habitat or food resources to
sustain them.
“But they haven’t even begun to
level off yet,” he said.
Is there a downside to having so
many eagles in the region? That’s a question that Peter Paton has pondered. An
ornithologist and professor at the University of Rhode Island, Paton said that
researchers have found that the approximately 900 pairs of bald eagles breeding
in Maine are eating so many gulls, eiders and great cormorants that populations
of those birds are declining. And many of the eiders and cormorants that summer
in Maine spend their winter in coastal southern New England. Which means that
eagle predation in Maine may be causing a decline in winter eider and cormorant
numbers in Rhode Island.
French, who assesses eagle prey
whenever he visits a nest to band young eaglets, said that the most common food
items he observes in nests are fish, primarily brown bullhead and chain
pickerel. But he also commonly finds the remains of Canada geese, wild turkeys,
gray squirrels and other prey.
“Most of what they eat aren’t things
we really need to worry about,” he said. “Sure, they’ll take a few things that
you wish they hadn’t, like common loons and osprey chicks, but they won’t
impact other species at the population level.
“For
all practical purposes in Rhode Island,” French concluded, “there’s no such
thing as too many eagles.”
This article first appeared in EcoRI.org on December 29, 2016.
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