Over the weekend, we traveled to southern Maine to see if we could observe the drama of heavy surf expected from the passing of Hurricane Erin far offshore. We spent a half hour or so at Fortune’s Rocks Beach in Biddeford Pool, where the water churned foamy white as the storm waves came thundering in. It was late in the day, under beautiful sunny blue skies with light winds that gave no indication that a massive hurricane was passing hundreds of miles to the East.

Just a hundred yards offshore, behind where the waves were breaking, a group of about 30 common terns, adults and juveniles, flew in a loose line, scanning the water for prey. When they reached the end of the beach, they would turn and zoom back up the other way to repeat their route. It was especially great to see the juvenile birds, distinctive with their dark bar across the front of the wing, knowing that they had been hatched this summer and would be back to nest themselves in a couple of years.

We scanned through the terns, enjoying the sight as we listened to the roar of the surf and  breathed in the salt-laden air. Then we noticed a different tern among the commons—a tern with a black mask contrasting with a white head and nape and only a little black on the outer part of the gray upperwing. It was a Forster’s tern. As we continued watching we realized that there were two more traveling with it—three Forster’s terns!

Forster’s  terns don’t nest in Maine, but a few show up on the Maine coast (especially the southern Maine coast) in late summer and early fall every year. This year, there seems to be a good number of them around the coast south of Portland, with a few scattered north of there including in Thomaston Harbor and off Eastport.

Forster’s terns have a very interesting breeding distribution, with populations nesting inland from south-central Canada into the Great Plains, western Great Lakes, and western U.S. Birds also nest along the coast in California, the mid-Atlantic states, and the Gulf Coast into northern Mexico. Unlike many of our other breeding terns that go much farther south, Forster’s terns winter from the southern U.S. south to Costa Rica and Panama and to Bermuda.

Where the Forster’s terns come from that make their way to Maine in late summer is a mystery. Are they coming north from the mid-Atlantic? Or do they originate in inland breeding colonies far to the West? Forster’s terns even show up with regularity in the British Isles in late fall and winter. Do some of the birds we see in Maine just keep going east until they cross the Atlantic?

Just to be clear, Forster’s terns are not a species we expect to be swept up in hurricanes and taken far off course like tropical terns sometimes are. The Forster’s terns that are being seen this summer are part of a normal but interesting pattern that delights birders even if we don’t understand exactly what it’s all about.

Incidentally, we just discovered that the so-called type specimen (the specimen from which the species was first described to Western Science), was procured from one of the world’s largest inland freshwater deltas, the Saskatchewan River Delta that stretches across the Saskatchewan-Manitoba border and is a hugely important place for birds.

Now it will be interesting to see if Hurricane Erin has brought and left behind some especially rare-to-Maine birds!

Jeffrey V. Wells, Ph.D., is a Fellow of the Cornell Lab of Ornithology and Vice President of Boreal Conservation for National Audubon. Dr. Wells is one of the nation's leading bird experts and conservation biologists. He is a coauthor of the seminal “Birds of Maine” book and author of the “Birder’s Conservation Handbook.” His grandfather, the late John Chase, was a columnist for the Boothbay Register for many years. Allison Childs Wells, formerly of the Cornell Lab of Ornithology, is a senior director at the Natural Resources Council of Maine, a nonprofit membership organization working statewide to protect the nature of Maine. Both are widely published natural history writers and are the authors of the popular books, “Maine’s Favorite Birds” (Down East Books) and “Birds of Aruba, Bonaire, and Curaçao: A Site and Field Guide,” (Cornell University Press).