By TODD McLEISH/ecoRI
News contributor
Walking on the beach at
the north end of Block Island last month, Matt Schenck stumbled upon two dead
and decomposing seabirds, which the avid birdwatcher identified as great shearwaters.
While gulls of various species are commonly found dead on local beaches,
shearwaters are an extreme rarity.
Except this year.
Hundreds of great
shearwaters have turned up dead on beaches on Long Island and southern New
England this summer, and no one seems to know why. In addition to the birds on
Block Island, birders and biologists have reported dead shearwaters on Rhode
Island beaches in Tiverton and Charlestown.
Shearwaters spend most
of their lives far out to sea, where they soar just above the waves as they
forage on small fish and other marine creatures near the surface of the water.
Four species of shearwater — great, sooty, Cory’s and Manx — are typically seen
in Rhode Island waters, though they seldom travel within sight of land. Most breed
on remote islands in the South Atlantic.
“There has been an
abundance of sand eels in our local waters, which are a forage fish for
shearwaters,” Beuth said. “As a result of them being closer to shore than
usual, it would be more likely that they’d wash up on shore if they died.”
While prey may be
abundant, some biologists, including Linda Welch, a U.S. Fish & Wildlife
Service biologist who studies great shearwaters off Cape Cod, have noted that
many of the dead birds are juveniles that have been thin or emaciated,
suggesting that the birds have starved.
The dead birds began to
show up on beaches in late June, which is about when they should have arrived
along the East Coast after their long migration from their breeding grounds in
the South Atlantic. By then, they were likely stressed and tired and hungry,
which may have made them susceptible to any number of potential sources of
mortality.
Wildlife pathologist Joe
Okoniewski examined some of the dead shearwaters found on Long Island beaches,
and he told The New York Times that the birds were not only thin but anemic.
“The big mystery is: Why are they thin? On the surface, it looks like you know
what happened — they starved,” he said. “But when you ask why, it becomes much more
of a mystery.”
It is especially
mysterious if prey is seemingly abundant, as it has been this summer in Rhode
Island waters.
Robert Kenney, an
oceanographer at the University of Rhode Island’s Graduate School of
Oceanography, speculates that toxic algae from red tides may be playing a role
in the bird deaths. He said a number of northern gannets, another species of
seabird, have been found dead on Cape Cod beaches this summer. The only
difference, he said, is that they are “in good condition, except for being
dead.”
He noted that toxic
algae may have also contributed to the deaths of some of the numerous whales
that have been found dead along the East Coast and in the Gulf of Saint
Lawrence this year.
Among those trying to
find an answer is Julie Ellis, director of the Seabird
Ecological Assessment Network at the Tufts University
Veterinary Medical Center, which uses volunteers throughout the Northeast to
regularly walk beaches to collect dead birds for study. She is reaching out to
a number of animal diagnosticians throughout the region in hopes that together
they can come up with a consensus of what is causing the shearwater deaths. She
hopes they will have an answer next month.
Rhode Island resident
and author Todd McLeish runs a wildlife blog.