Terns difficult to identify, but abundant in Maine

Arctic terns are usually the toughest to spot from shore, although they are abundant around their nesting colonies.
Courtesy of Bob Duchesne
Arctic terns are usually the toughest to spot from shore, although they are abundant around their nesting colonies.
Posted July 20, 2012, at 11:59 a.m.

To everything there is a season, tern, tern, tern. Now is the time to look for our five breeding terns in Maine: common, arctic, roseate, least and black. Terns are similar to gulls but sleeker and more elegant. They are graceful flyers and typically dive for small fish.

Identification of terns is a challenge. Three of them are very similar in size and color, and guidebooks describe them collectively as “medium-sized terns.” Of these, the common tern is the most familiar. It’s the only species that nests on Maine’s freshwater lakes, as well as the offshore islands favored by the other species. Don’t be surprised to find common terns on Moosehead and the more remote lakes of northern Maine where they nest on small islands. There’s a good nesting colony on Long Lake near St. Agatha. Often, when I scan the lakes from the Million Dollar View in Weston, I can pick out common terns sitting on the rocks a half mile away.

Breeding grounds for arctic and roseate terns are limited to about two dozen coastal islands. Roseate terns nest on only a few of them, because they nest in thick vegetation not found on many Maine islands. Arctic and common terns nest on open scrapes in rock or short grass, barely perceptible. The eggs are colored to match the soil, so the nest and its contents are almost invisible when not occupied. When I participated in a tern restoration project about 15 years ago, it was all I could do to avoid stepping on the nests.

Maine’s population of terns is relatively healthy and perhaps growing. But it is only half the number we once had. Populations peaked in the 1930s after surviving a fashion trend that encouraged women to wear dead birds on their heads. The terns proved less able to fend off new competition from gulls, drawn to the state by the garbage feast at coastal dumps. Not only did the opportunistic gulls eat tern eggs and chicks, they vied for the same nesting space on offshore islands. Most nesting islands are now under government ownership, and wise conservation efforts have restored the balance somewhat.

Arctic terns are usually the toughest to spot from shore, although they are abundant around their nesting colonies. We have thousands of nesting pairs. They prefer sites farther from the mainland shore and are less likely to forage near land. Arctic terns are the migration champs of the world, following a circumpolar route that zigzags from Canada to the southern tip of Argentina — a round trip exceeding 44,000 miles.

There are fewer than 200 roseate terns in Maine, and they are federally endangered. Fortunately for birders, they nest in a few places convenient for mainland viewing. One of their colonies is on Stratton Island near Scarborough. With patience, it is possible to pick one out as flocks of terns come in to forage at Pine Point in Scarborough Marsh. Popham Beach State Park and nearby Fort Popham in Phippsburg are also good places to look. The puffin boat tours to Eastern Egg Rock are almost certain to provide passengers with a view of a roseate tern, since about half the population in Maine nests there.

One good tern deserves another. Least terns are beach nesters, which is why they are also endangered. They are the smallest terns in North America, a third smaller than the “medium-sized” terns. Their nests are mere depressions in sand and they are easily disturbed by people, dogs and Frisbees. They can be found on the north end of Wells Beach, Popham Beach State Park and Reid State Park. They also nest on islands near the mainland, including Stratton Island, and they are regularly seen foraging at Pine Point in Scarborough Beach. If you get a good look in the binoculars, a black-tipped yellow bill is distinctive.

The black tern is our fifth breeder. This is a bird that is at the northern edge of its range in Maine and it is a state endangered species. Unlike the others, it nests exclusively in freshwater marshes. There are several colonies in central Maine, but it is best seen from the boat launch at Messalonskee Lake in Belgrade. See it now while you can. They turn white and leave early for a winter in ocean waters off Central America.

I apologize for the puns this week. It seems my writing has taken a tern for the worse.

Bob Duchesne serves in the Maine Legislature, is president of the Penobscot Valley Chapter of Maine Audubon, created the Maine Birding Trail and is the author of the trail guidebook of the same name. He can be reached at duchesne@midmaine.com.

 

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