Cause Of Seabird Die-off Along Coast Remains Unknown

By: Tim Wood

A dead seabird on Harding's Beach. TIM WOOD PHOTO

CHATHAM – Rebecca Catron regularly walks down Harding's Beach, past the parking lots toward the eastern tip of the beach. In July, she began noticing more and more dead birds on the beach and in the water, sometimes several within a few feet.

“I was thinking gosh, this is not normal,” she said during a walk down the beach last week. “I'm used to seeing one or two dead birds, but this is extreme.”

It turns out that she's right; there are more dead birds washing up along the shore this season than is usual. Wildlife officials are in fact investigating an apparent die-off of seabirds, including shearwaters, gannets, eiders and kittiwakes, that was first observed this spring from Cape Cod to southern Maine.

“Pathologists are working through [reports] to help identify the cause(s),” Chris Dwyer, a migratory gamebird biologist with the U.S. Fish and Wildlife Service's Northeast Region, said in an email. Similar die-offs have been reported further south, he added, but causes are as yet unknown.

Such a die-off is unusual on the Cape for species such as shearwaters, he added. Similar occurrences in the mid Atlantic states and New York were attributed to starvation.

“Until we have reports back from pathologists located at several labs in the Northeast, Southeast and Midwest, we won't know if this is related to what has been occurring further south, or some other factors that are more local,” Dwyer said.

Exact numbers are uncertain. Catron has documented dozens of dead shearwaters, terns, gannets and other species along Harding's Beach, and Kate Iaquinto, a wildlife biologist at the Monomoy National Wildlife Refuge, said 10 shearwaters washed up dead on the refuge two weeks ago.

“It's part of a larger thing that's happening, but we don't know exactly what it is,” she said. It seems to be isolated to shearwaters and other pelagic seabirds has hasn't impacted the refuge's tern colony. Last year, a bacteria infected and killed quite a few terns on Monomoy, but that didn't happen this year.

“This year we had very little deaths in the colony,” Iaquinto said.

When dead birds are found in the swimming areas along town beaches, lifeguards remove them and bury them in the dunes, said Park Director Dan Tobin. Occasionally a park department employee drives down the eastern end of the beach and removes dead birds. He added that dead birds have also showed up in Pleasant Bay and near Lighthouse Beach this summer.

Catron has also come across more dead seals along Harding's Beach this summer than in past years. Several remained on the beach for some time, resulting in a nauseating odor.

While there's a protocol for dealing with live seals stranded on the beach – Tobin said he calls the International Fund for Animal Welfare's Marine Mammal Stranding Network – the town is left to deal with dead seals on its own, as time and manpower allow. If the animal is freshly dead, they sometimes notify IFAW. But dead seals have become so commonplace that IFAW is not interested in doing as many necropsies as in the past.

“Some of them are in pretty tough shape once we get them,” Tobin said. Some have obvious injuries – deep wounds caused perhaps by sharks or boat strikes – and some have been preyed on by coyotes, something officials want to discourage near popular beaches. Tobin said when he's made aware of a dead seal, the policy is when possible to “dig them where they die,” meaning they are buried on the beach.

“We push them up (on the beach) enough so we can get them deep enough and not hit water,” Tobin said. That can be problematic on sections of Harding's Beach where erosion has carved back the dunes and left little beach area.

Catron said it's distressing to see so much dead wildlife along the beach. Other than notify authorities, there's not much she can do about it. Recently she saw a bird on the beach that was alive but appeared “almost like it had a broken wing.” By the time she called wildlife rehabilitation agency Wildcare, the bird was dead.

“It looked healthy,” she recalled, adding that it was amid a large pile of seaweed, which can sometimes be several feet thick on the beach.