The life of the plucky tern is one beset on all sides by danger. They face a staggering array of threats from above and below as they eke out an existence hurling their angular, streamlined bodies toward the sea in search of sand eels and lance. For The Trustees of Reservations, protecting the diminutive shorebirds is a constant effort, one that begins in the spring before the terns arrive and ends long after the last bird has left.
In recent decades terns have staged a spectacular comeback, having faced near extinction at the turn of the 19th century at the hands of the feathery fashion whims of high-society milliners and again after World War II as recreational beach use exploded.
At the height of this summer a colony of nearly 1,400 pairs of least terns, 200 common tern pairs and 26 pairs of the state and federally endangered roseate tern made a home on the Edgartown side of Norton Point. In a recent trip to the barrier beach, Trustees of the Reservations acting coastal ecologist James Brady said the colony at Norton Point may represent up to a third of the total population in Massachusetts
“It was pretty impressive when there were 1,400 pairs here,” he said. “If something spooked them it was a cloud of white.”
Now though, as the dog days slip away, the colony is a shade of its midsummer multitude and the scene at Norton Point more closely resembles a winged cadre of party stragglers who have overstayed last call.
It was a long summer for the terns and the Trustees staff who witnessed both the triumph of productivity among its least terns as well as a slow-motion massacre among the roseates and common terns.
One of the most pernicious threats any shorebird encounters is mammals. At the beginning of the summer the territorial least terns established a colony on one end of the beach and the commons and roseates established their own colony on the other. But before they had even arrived, Trustees staff laid thousands of feet of skunk fencing around the historical nesting sites. Despite the efforts, an unwelcome intruder began to make his presence dreadfully felt by midsummer. Every morning Trustees rangers observed a trail of tracks over the ineffective barriers and into the roseate and common colony, as well as an increasing shortage of eggs. Mr. Brady even procured electric fencing from the Trustees Ipswich office to supplement the skunk fencing, but it was too late.
“At that point he had a taste for the eggs and there was essentially an unlimited supply of food. We even had a local trapper come in, but he couldn’t get him. The skunk would walk right next to the trap; it was unreal,” he said.
“It was kind of just waiting and waiting, and every night it was more nests and more nests.
“Then they were gone,” he said with a sickening finality. “All the eggs and fledglings were wiped out in the roseate and common tern colony.”
Eventually, desperate and forlorn, the commons and roseates made their way over to the least tern colony which compassionately adopted them and provided protection, fearlessly attacking their outsized gull and skunk predators in coordinated dive bombings. Mr. Brady said at least a few refugee roseates and commons were able to fledge this season after the exodus.
“Initially they established separate colonies because they can be aggressive toward each other, but by the end of the summer these guys had nowhere else to go.”
While the Trustees work tirelessly to protect them, the terns do not always appreciate the ministrations of their human guardians.
“They can defecate with incredible aim,” said Mr. Brady, with the authority of someone who had endured one such barrage.
“I’m talking behind the sunglasses aim.”
Despite the affront, Mr. Brady finds the little guys endearing. One reason is their mating ritual, which is among the more bizarre spectacles of nature encountered in his daily patrol.
First the male must prove his fishing mettle to the female tern who watches with feigned disinterest as he doggedly retrieves fish for her consumption. Once he has established himself a worthy suitor the male is then allowed to consummate his relationship with the female.
“He gets on her back and swings a fish in front of her face and copulates at the same time,” Mr. Brady said. “Then he feeds it to her when he’s done.” What a gentleman.
Now the fish-swinging and mating is over and the colony has all but disappeared, bound for South America, with likely stopovers in the Gulf of Mexico.
“It’s scary to think about. There will be biologists studying the effects of the spill on shorebirds for the majority of their careers,” Mr. Brady said.
And once their summer residents are gone, the Trustees turn their attention toward roping off and protecting the terns’ beloved dune grass from oversand vehicles and curious beachcombers, making sure that their return next year is as comfortable as possible.
“It’s a labor of love,” said Mr. Brady.
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