Migration is a system of organized chaos. Sure, songbirds fly south for the winter. But they might fly north, west or east, or just fly around randomly before heading south. Eventually, most of them will end up on their normal wintering grounds, but getting there is half the fun.
I grew up thinking that birds flew south in prearranged fashion, following the arrows drawn on maps that depicted the Atlantic Flyway, the Mississippi Flyway, the Central Flyway and the Pacific Flyway. That’s what my books told me. I suppose most birds do behave according to such models, but there are a bunch of rogues out there that make life interesting this time of year.
In early September, our birds depart predictably, following favorable winds southbound. If our own birds wander elsewhere we wouldn’t know it — out of sight, out of mind. What we do know is that some birds departing from elsewhere end up here. By late September, anything can happen, and often does.
Many species enter a period of post-breeding dispersal. They nest in predictable places, and when those chores are over, they wander. The best example in Bangor has been teasing birders for over a month. Great egrets nest in southern Maine. This year, a bunch of them wandered up here during post-breeding dispersal and took a liking to Essex Woods. They are so conspicuous, they can be seen from the highway by passing motorists. Eventually, they’ll fly south.
Some birds deliberately wander. Ruby-throated hummingbirds are the only nesting hummingbirds east of the Mississippi, but some western hummingbirds wander east when they are done nesting. The rufous hummingbird, in particular, has a habit of drifting into Maine later in autumn. Although most of our hummingbirds are gone by mid-September, I always advise leaving feeders up until frost. You never know what might visit in October.
Some birds get blown off course in bad weather, especially those that have a habit of wandering anyway. Cave swallows nest in the Caribbean, with small colonies in Florida and Texas. They are famous for wandering after breeding, and they aren’t particularly troubled when blown north. They sometimes show up along the Maine coast in October.
Migration forces many species to fly long distances over water. They really don’t want to. It’s a big risk. But their wintering grounds are on the far side of the Caribbean and there is little choice. Songbirds from Atlantic Canada typically work their way down the coast of Nova Scotia, meandering back and forth until they get up the courage to cross the Gulf of Maine. They touch down on the first land they find, or even on boats if necessary.
Maine islands are notorious migrant traps. King of these is Monhegan, 10 miles from the midcoast mainland. While many Maine inns are reaching the end of their peak seasons, the inns on Monhegan are typically full this time of year. Birders flock from everywhere to see what rarities have fallen out there.
Although Monhegan is only a mile long, there are 17 miles of walking trails crisscrossing the island. However, many of the visiting birds merely forage around town where there are bushes, hedges and ornamental fruit trees. It can be possible to find 20 species of warbler in a morning. Generally, the birds are so tired and hungry that they ignore people. Close, easy views are the norm.
However, it is the likelihood of rare birds that attracts so many birders to Monhegan in late September. Lark sparrows nest from the Great Lakes to the west coast, nowhere near Maine. A few turn up on Monhegan every autumn. Clay-colored sparrows are expanding their breeding range eastward into Maine, but only in miniscule numbers. The ones that turn up on Monhegan in autumn have likely gotten lost and wandered from the Midwest.
Summer tanagers are a southern bird, with a nesting range north to New Jersey. Somehow, a few end up on Monhegan every autumn, and that is decidedly in the wrong direction for a bird that should be heading to the tropics.
You’d have to go to the grasslands of central states to find a nesting dickcissel. I saw my first in Tennessee on June 26, 1999. Western kingbirds reside west of the Mississippi. Both species are infamous wanderers in the fall, and Monhegan vacuums up any bird that roams into the Atlantic.
Don’t think of yourself as planning too late for Monhegan this year. Think of yourself as planning early for next year.
Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information atmainebirdingtrail.com. He can be reached at firstname.lastname@example.org.