Here in Maine we are in the midst of the fall migration of birds. Waves of warblers, sparrows, thrushes, and other species are passing through daily—and nightly, as most birds migrate at night. We are all familiar with this ebb and flow of birds that leave the north as it gets colder and return again in the spring after a winter in warmer southern climes.

But have you ever thought about how migration might work in the southern hemisphere? In southernmost South America during our summer birds are enduring the cold of winter; in our winter they are basking in the southern summer. So some birds that breed in southern South America during that southern summer (our winter) migrate north to northern South America to escape the cold conditions of the southern winter (our summer). This is called austral migration.

One of the species that makes that epic South American migration is the fork-tailed flycatcher. Typically during our spring, fork-tailed flycatchers from southern South America migrate north to northern South America where they stay until our fall, when they fly south to greet the onset of the southern summer.

Fork-tailed flycatchers are well-named. They are part of the flycatcher family, as are our familiar eastern phoebe and eastern kingbird. In fact they look quite similar in size, shape, posture, and activity to an eastern kingbird except for one dramatic difference: they have an incredibly long and deeply forked tail. Some young or molting fork-tailed flycatchers have much shorter tails and could conceivably be confused with a kingbird. But if the bird is carrying its dramatic tail, there is little else that looks remotely similar.

So when someone spotted one at Gilsland Farm Sanctuary in Falmouth last week, there was little doubt that the observer had made a spot-on identification. The only other flycatcher that has a tremendously long tail like this and that has been recorded in Maine is the aptly named scissor-tailed flycatcher, a bird that nests in parts of Texas and Oklahoma but that is much lighter overall and lacks the black head of the fork-tailed flycatcher.

It didn’t take long for the news of the fork-tailed flycatcher sighting to spread through the birding community. Over the weekend and continuing as we write this, large numbers of birders from Maine and throughout New England were making the trek to see the bird.

This was not Maine’s first fork-tailed flycatcher. We remember searching without success for one that had briefly appeared in Brunswick in 2012. One was photographed out on Stratton Island near Scarborough in 2011. It turns out, there have been perhaps 8-10 sightings of fork-tailed flycatchers in Maine stretching at least as far back as the 1970s and perhaps earlier. Across the U.S. there are nearly 200 records of wayward individuals of the species.

While there is a subspecies of fork-tailed flycatcher whose range extends from southern Mexico south into Central America, virtually all the fork-tails that have been found in the U.S. are known or thought to be of the migratory South American subspecies. What is thought to happen to these birds is that when they are ready to migrate south from northern South America to southern South America during our fall, something causes their brains to mix up their north-south directionality. So instead of heading south, they go in the opposite direction and make a 2,000 mile trip north to arrive in a place like Falmouth, Maine, instead of a place like Puerto Madryn, Argentina!

It’s a heck of a wrong turn to make, and we hope that our Maine fork-tailed flycatcher will stock up on food and figure out soon that he needs to head back south to find summer again.

Jeffrey V. Wells, Ph.D., is a Fellow of the Cornell Lab of Ornithology. Dr. Wells is one of the nation's leading bird experts and conservation biologists 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 book, “Maine’s Favorite Birds” and the just-released, from Cornell Press, “Birds of Aruba, Bonaire, and Curaçao.”