May is bird heaven in our region. All the species that headed south the previous year are back: the flycatchers, vireos and thrushes; the warblers, wrens and swallows; even the ruby-throated hummingbirds and scarlet tanagers are in full force. But May and its riches of bird seems distant in early March – too far into the future to even contemplate.
The first day of spring, on the other hand, is just around the corner. And while the Adirondack air may still be frigid and the ground often snow-covered, bird populations are nonetheless on the move. By St. Patrick’s Day or shortly thereafter, killdeer, tree swallows, eastern meadowlarks, phoebes and robins will be flitting through our woods and fields again. Red-winged blackbirds sometimes show up as early as late February.
Why do these birds return when winter can still pack a punch? The short answer is competition, explained Steve Hagenbuch, a conservation biologist with the Vermont Audubon Society. “The birds are coming back here with one purpose in mind – to raise the next generation of their species.” The sooner they arrive, the better positioned they are to claim quality nesting habitat and find a mate. “If you arrive late to the party, you may be relegated to suboptimal habitat and be quite lonely.”
The early arrivers are the short- and medium-distance migrants. For example, that tree swallow checking out bird boxes in your field may have wintered in Florida; the Eastern phoebes in your hedges may have spent the cold months in the Carolinas. As for that red-winged blackbird perched among the cattails, it may have ventured no farther than the marshes of Long Island.
While weather conditions can influence a bird’s decision of what day to start its journey north, it is the increasing number of daylight hours that triggers the impulse to migrate. The lengthening days stimulate a bird’s pituitary glands, which drive the urge to mate, said John Buck, a wildlife biologist with the Vermont Fish and Wildlife Department. Which explains why I have heard male red-winged blackbirds singing away on bitterly cold, snowy March days. “Their hormones are telling them what to do,” said Buck.
It’s not just songbirds returning during the waning weeks of winter. Wood ducks are also among the first to arrive. These short-distance migrants start showing up from late February to mid-March. Unlike other birds, wood ducks don’t have to spend any time upon their return looking for a mate: pairs are formed prior to migration and the trip back is made together. For those of us eager to see some flashy spring plumage, there are few birds as stunning as male wood ducks during breeding season. With their teal heads, spotted cinnamon breasts, orange eyes and beaks, they are the perfect antidote to the dreary late-winter landscape.
Though there are advantages to early arrival, there are risks too. Late winter and early spring storms take their toll, including toppling trees with nests in them. But the balance of risks and opportunity has, overall, favored the bold. “A few birds might die,” said Buck, “but it doesn’t kill the species.”
As March progresses, I find myself listening more carefully, rejoicing in the first trills of red- winged blackbirds. Nothing heralds spring – if not the arrival than at least the promise of it – more than that beckoning call. Soon other travelers will arrive, adding their voices to the warming air. It’s an amazing feat that these tiny creatures cross hundreds, sometimes thousands of miles. The scope of what is about to unfold, said Buck, is breathtaking. “One day [a bird] gets up and flies, not to the next tree, but to the next latitude. It’s one of the marvels of evolution and of bird life.”
Carolyn Lorié lives in Post Mills. The illustration for this column was drawn by Adelaide Tyrol. Photo of mated wood ducks on the Ompompanoosuc River courtesy Tig Tillinghast. The Outside Story is assigned and edited by Northern Woodlands magazine, and sponsored by the Wellborn Ecology Fund of New Hampshire Charitable Foundation.