forests prevail in the southern and central interior parts of the state.
Boreal forests take over in parts of Baxter State Park and at the North
Maine Woods. Maritime forests and cedar swamps along the northern coast
provide similar habitat for boreal species. These forest types mix at
transition points, and birds of the different habitats can be found close
The coast, too, is in transition. The extensive sand beaches of southern Maine give way to the "rocky coast of Maine" just north of Portland. But there are enough rocky capes along the coast of southern Maine that species overlap and it is possible to find a sand-loving Sanderling with rock-loving Purple Sandpipers. And though the salt marshes and estuaries of southern Maine are extraordinary for shorebirds in late summer, the mudflats uncovered by the huge tides of northern Maine are their equals.
Glaciers produced much of the diversity. Where the weight of miles-thick ice depressed the earth, the sea advanced temporarily as the glaciers retreated, depositing marine clay into areas that would eventually lift and become peat bogs. Yet alluvial deposits of sand from the same retreating glaciers formed gravel eskers. Thus, systems of well-drained and poorly-drained soils exist right next to each other.
Salt marshes and freshwater marshes coexist along the entire coast and many species are equally at home in both. Saltmarsh Sharp-tailed Sparrows and Nelson's Sharp-tailed Sparrows both breed in the state. They overlap, and even hybridize, in places like Scarborough Marsh and Weskeag Marsh. In fact, Maine is the northern limit of many southern species and the southern limit of many northern species. Some offshore islands, and even a few mainland parks, are notorious migrant traps. For instance, Monhegan Island is the destination of choice for many international bird tour groups because of its propensity for attracting a staggering diversity of off-course migrants.
Maine deserves its reputation for seabirds. The warm waters of the Gulf Stream bypass the icy waters of the Gulf of Maine, making it a natural factory for producing sea life. Maine's lobster industry is world-famous and these same cold conditions produce abundant food for whales and birds. Offshore islands are ideal for nesting where Atlantic Puffins raise their young under the protection of Common, Arctic, and Roseate Terns. Colonies of Common Murres, Razorbills, and Black Guillemots dot the islands. Leach's Storm-petrels nest offshore and post-breeding Wilson's Storm-petrels move into the same waters each season, along with at least three species of shearwaters, Northern Fulmars, Northern Gannets, migrating jaegers, and rare skuas.
In breeding season, warblers are everywhere. Two dozen species are possible. Yellow-rumped, Black-throated Green, Northern Parula, Black-and-white, and Magnolia warblers are all so common it's hard to imagine a day in the field without encountering them. So are American Redstarts, Common Yellowthroats, and Ovenbirds. Yellow Warblers dominate city parks and the brushy open areas of the coast, river bottoms, and logging cuts. Chestnut-sided Warblers favor secondary growth areas. Large stands of Maine's famous White Pine, especially near lakes and rivers, are bound to contain a few Pine Warblers. Black-throated Blue and Nashville Warblers are relatively common in mixed forests, just as Blackburnian Warblers are likely to be present in the canopies of more mature forests.
Other warblers share a more limited range or season. You may have to chase Canada Warblers deeper into wet, tangled thickets. Wilson's Warblers favor the live alders around wet areas of small ponds and streams, especially in the northern forest, while the Northern Waterthrush prefers the upright dead trees of beaver flowages. Blackpolls are relatively late migrants, most heading for the alpine/spruce forests of Atlantic Canada, but findable in our own boreal forests in the mountains of Western Maine, Baxter State Park, and spruce forest tracts far up the coast. Palm Warblers are one of the earliest migrants, often arriving in the state in April. By mid-May, they've already begun to disappear into their boggy breeding grounds where Tennessee Warblers are also infrequent breeders. Cape May Warblers prefer the tall conifer forests and edges more common to northern Maine, while Bay-breasted Warblers tolerate hardwoods in boreal areas. Mourning Warblers are present in the deciduous ravines and tangled undergrowth of northern Maine but challenge even the best local birders to find them. In contrast, the range of Prairie Warblers barely extends into southern Maine and they are seldom encountered north of Augusta. Blue-winged Warblers are occasional in some well-known locations in southern Maine. Sightings of Orange-crowned, Hooded, Worm-eating, Golden-winged, and Kentucky Warblers are rare but recurring events in migration.
Red-eyed Vireos are present in all mature woods. Where woods are not fully mature, Blue-headed Vireos predominate. In a day of spring birding, you can't miss either one. Warbling Vireos are present in open deciduous areas, especially bordering on farm and pastureland, as well as wetland areas. Philadelphia Vireos may be encountered in migration, but seemingly disappear into their forested breeding grounds, breeding in Maine primarily in the Baxter State Park area. Yellow-throated Vireos breed in a few areas of southwestern Maine, especially Brownfield Bog.
You can't miss Herring, Ring-billed, and Great Black-backed Gulls. There are plenty of Laughing Gulls, limited to salt water. Bonaparte's Gulls are locally common, usually after breeding. Black-legged Kittiwakes nest between the US and Canada along the downeast coast, and they can roost by the hundreds within easy view..There are several very good spots for locating Iceland and Glaucous Gulls in winter. The culprits that get the notice of local Rare Bird Alerts are the Common Black-headed Gull, Lesser Black-backed Gull, and Little Gull. Don't get your hopes up, but don't rule them out either.
One caution: In northern areas and on logging roads throughout Maine's forests, never trust a cell phone or GPS. Roads and conditions are subject to change. Cell phone signals are sporadic at best.