During these still-cold days of March, we celebrate any of the earliest returning birds of spring—red-winged blackbirds, American woodcock, turkey vultures, perhaps robins in your neighborhood (though there are some around various parts of the state all winter). Once we see any one of these species, we can usually expect that they’ll be part of our daily lives for many months until late fall when they head south again for the coldest months.

Then there are the birds that spend the winter with us and that one day suddenly are no longer in their familiar places—the rusty-headed American tree sparrow at the backyard feeder, the rough-legged hawk in the farm fields, the purple sandpiper on the rocky offshore island, the bufflehead in the bay. All of these species will leave us soon for breeding grounds far to the north. We won’t seen them again until late fall.

But most fleeting are the birds that pass through our state only during a brief window of time each spring and fall. These are species that winter largely to our south and that have most of their breeding population well to our north.

From March through mid-April they quickly slide through like some kind of mysterious itinerant travel, perhaps only stopping for a day or two here and there along the way. Some lucky birder may get a glimpse of them; others will have to wait until next fall to try.

One of the most fleeting early pass-through migrants is the fox sparrow. A few fox sparrows do sometimes winter in the state (one was on Matinicus Island this year for the Christmas Bird Count) and a few now nest in northern Maine. But fox sparrow sightings peak in Maine from mid-March to early April, and most of these are headed north into Canada. If you don’t catch a glimpse of one of these big, rusty-colored sparrows now, you may be out of luck until next fall.

A whole host of waterfowl are in the category of these migrants that pass through quickly in spring—snow goose, gadwall, American wigeon, northern pintail. Watch for them in the muddy melting marsh and pond edges where they may stop for a day or just a few hours before moving on. The newly ice-free Merrymeeting Bay marshes at the mouth of the Abagadasset River in Bowdoinham is one of the few spots in the region that can sometimes host many of these species and more, along with hundreds (or occasionally thousands) of mallards and American black ducks.

We’ve written also about the spring concentrations of what we sometimes like to call the “ice ducks,” officially known as common mergansers. Beginning when larger areas of water open up within the still ice-locked Kennebec River and other large rivers, one begins to see groups of the long, dark-headed and gleaming white-bodied male mergansers. As the season progresses and the river eventually flows dark and open with only scattered ice flows along its banks, the flocks grow bigger, looking at a distance like small, white floating ice chunks themselves. Soon the numbers may grow into the hundreds within a small stretch of the river, and if you look closer you will see more and more of the females, better camouflaged and equally beautiful with subtle gray bodies and chocolate brown heads. Common mergansers do breed in Maine and winter here as well, but it is only in early spring when these impressive numbers of them build up in rivers like the Kennebec as they funnel farther north to nest.

One final species we will mention that makes a quick migration through Maine in March and early April is one that many of you may find surprising—the lesser black-backed gull. This species, once an extreme rarity in the eastern U.S. and Canada, now is an uncommon but regular species here in Maine. A population of the species has expanded in Greenland, with many or most of them now migrating south to the Mid-Atlantic region of the U.S. to winter. Those birds move quickly through Maine in late March and early April as they head back to Greenland to nest. Look for a dark-backed gull with yellow legs instead of the pink legs of great black-backed or herring gulls.

Enjoy them all while you can!

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 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” (Tilbury House) and “Birds of Aruba, Bonaire, and Curaçao: A Site and Field Guide,” (Cornell University Press).