A pair of bald eagles was spotted recently by an Island angler as the birds were attempting to establish a nest on a vacant osprey pole in West Tisbury. The sighting could herald a new, more permanent presence of the species on Martha’s Vineyard (though not if the osprey have anything to say about it).
As an avid fisherman, Islander Stavros Viglas said he has been anxiously awaiting the arrival of striped bass, and was searching for signs of spring one day when he saw the massive birds.
“Checking the osprey poles, listening for peeper frogs, and enjoying the longer days,” Viglas said. As he was inspecting one of the poles, he noticed two very large birds. When he scoped in on his binoculars, he noticed they were bald eagles. “Having never seen a bald eagle on Martha’s Vineyard before, I was very excited, and seeing a pair nesting is rare,” Viglas said.
The next day, Viglas said, he observed them collecting debris to make a nest on a pole near the water. Viglas recalled the size and beauty of the eagles.
“It’s something I will never forget,” he said. “I hope they stay, and I am glad I can share the experience.”
MV Times “Wild Side” columnist, Island ecologist, and birder Matt Pelikan said he sees the eagles attempting to nest as a promising sign, but it takes a lot for a species to get established in a new locale.
Last year, there was a pair of bald eagles spotted on Cape Cod that fledged young — but the birds had taken up residence in an old osprey pole, and the osprey weren’t happy about it, Pelikan said. “I’m not entirely sure they are the same birds, but they set up shop, and then got roasted by the osprey that had presumably been the original owners of that pole,” Pelikan said. “That could happen in this case this year.”
Earlier this year, a documented sighting was reported at Great Pond in Falmouth by the Falmouth Enterprise. Since then, there have been numerous social media reports of several bald eagles on Sider’s Pond, in the vicinity of Falmouth Town Hall.
With both bald eagles and osprey able to live to around 20 years old, Pelikan explained, the birds get better and better at nesting, reproducing, and fledging young as they mature. “If these eagles were breeding for the first time last year, they were susceptible to being chased off by osprey,” Pelikan said. “They would disturb the eagles so much that they ended up breaking their own eggs and abandoning the nest — but they may be smarter than that this year; they may have learned from that experience.”
In 2018, Pelikan wrote in his column that it would be unlikely to see bald eagles nesting here anytime soon, “but I’m happy my assumption was wrong.”
Now, he thinks it’s inevitable that the Island will have a successfully nesting pair, then multiple pairs down the line.
Although eagles have bigger nests and aren’t as tolerant of human activity, Pelikan said, they like to nest in similar locations as osprey, with a good sightline and easy access to food.
“I don’t think you are going to see a pair of bald eagles nesting in the smokestack top down at the [Tisbury] Waterworks, but some of those osprey poles down along the great ponds, if I was a third-, fourth-, or fifth-year bald eagle, they would be looking pretty good to me at this point,” Pelikan said.
Around 10 or 15 years ago, Pelikan said, seeing even a single bald eagle on the Island was rare, but sightings have grown year by year as the population has continued to rebound.
In a 2018 population count conducted by the Massachusetts Division of Fisheries and Wildlife, 76 territorial pairs of bald eagles were identified in the state. A similar number of osprey are counted nesting on Vineyard poles each year.
The number of eagles that visit the Island annually is difficult to determine, Pelikan said, because of their transient nature. “Unless you had a really coordinated effort with people spaced out all across the Island, you would never be able to get an accurate, fixed count,” he said.
For the first time in the 23 years Pelikan has lived on the Island, he saw a bald eagle fly over his yard a few weeks ago.
Although bald eagles and osprey both eat fish, Pelikan explained that osprey eat almost exclusively fish, and are much more adept at catching them.
While osprey hunt fish in the water, “eagles are much more generalist,” Pelikan said. “They scavenge a lot more. They’ll take mammalian prey — they’ll even take other birds. Bald eagles can take pretty large prey. If they find a sickly fawn or something, they can probably kill it and eat it.”
He added that although he isn’t sure of the historical tally of bald eagles on Martha’s Vineyard, the pair spotted on the Cape last year was the first to settle in that area in over a century.
The population was previously in decline because of pesticide use.
“They were persecuted by people who thought they were preying on livestock, clobbered by DDT, of course, and once DDT was banned in 1972, the turnaround started almost immediately, and has steadily progressed since then,” Pelikan said.
An eagle takes about five years to reach its full, mature plumage, and by that time, Pelikan said, an eagle has plenty of experience finding food, and more importantly, reproducing.
Pelikan said that although eagles compete with osprey for food, he believes having their lasting presence on the Island would bolster the rebound of the species, and would make for some very exciting birding.
Because the birds need vast territories to hunt and spawn, Pelikan said, it is unlikely that the numbers we would see on Martha’s Vineyard would have any major impacts on local ecology.
Bald eagles are listed as a species of special concern in Massachusetts, so Pelikan said that, just as with any other large raptor species, it’s important to not disturb their nest, and foster the growth and presence of this beautiful and patriotic bird here on Martha’s Vineyard. “It will be clear they are here to stay when little eagle chick heads pop up above the edge of the nest,” Pelikan said.
To read more about bald eagles, visit the Division of Fisheries and Wildlife website.