I see frost on my neighbor’s roof and a skim of ice in the birdbath. We are hovering on the edge of winter. My local birds are hoovering up suet as quickly as I refill the feeder, fueling up to withstand the cold. I keep an eye on the hummingbird feeder too as the liquid in it disappears in a wink.
Will the hummers stay for winter? Who stays and who heads out for warmer climes? I ask myself this question every year at this time so I’ve turned to my bookshelf for some guidance. I’ve been reading a thick and every-page fascinating book on migration by Scott Weidensaul, Living on the Wind: Across the Hemisphere with Migratory Birds. The book opens with him staring out to sea—the Bering Sea—from a piece of shore he describes as: “this tendril of land is a global crossroads…a port of entry between Asia and America.” It is a place of arrival and leave-taking for thousands of migrating birds, a seasonal high drama that stars some of the most spectacular travelers of the bird world. He describes some of the birds that fly almost pole to pole, but Weidensaul also notes that some birds hardly bother. Even birds of the same species, take Dunlins for example, don’t all undertake similar journeys. He tells us that there are three different populations of Dunlins, each with a different strategy for coping with winter. It turns out, migration is not a simple all-up-and-out movement but involves a lot of back and forth and odd variations and choices.
Before I follow Weidensaul along all the possible lines of his map, I will just give you this point that he says underlies all the patterns birds follow: “Migration is, fundamentally, about food, not temperature; those birds that can continue to find enough to eat during the winter rarely migrate—why bother?—while those whose food supplies are seasonal must flee.” So, no pressure! Keep those feeders topped up!
Part of my interest in this question of migration centers on one of our most common birds, the American robin. As a child growing up in Alberta where winter is a long and serious affair, seeing the first robin every spring was an annual quest and a triumph of hope over dreariness. But here in the Pacific Northwest, do robins migrate? Is theirs a case of “Why bother?” On a walk the other day, the air was full of robins, whizzing back and forth, calling, landing and taking off, clattering and nervous-seeming. They gathered, as if readying for a journey, but just as quickly dispersed as if on private business separate from their flock. What was going on?
Robins, in my experience, don’t eat from feeders. My interest that day was from long affection for these handsome birds with their storybook bright red bellies and contrasting gray-black over-coats. And there was no ignoring their frantic movements and their piping voices. But the next day on my walk I didn’t see a single robin. Where had they gone? Did they finally make a group decision and fly away? Back home, I turned to my trusted source for all bird questions, the Cornell Lab for Ornithology website for answers to my query about robin migration behavior. They had this to say:
“One reason why they seem to disappear every winter is that their behavior changes. In winter robins form nomadic flocks, which can consist of hundreds to thousands of birds. Usually these flocks appear where there are plentiful fruits on trees and shrubs, such as crabapples, hawthorns, holly, juniper, and others.
When spring rolls around, these flocks split up. Suddenly we start seeing American Robins yanking worms out of our yards again, and it’s easy to assume they’ve “returned” from migration. But what we’re seeing is the switch from being nonterritorial in the winter time to aggressively defending a territory in advance of courting and raising chicks.”
The clue to the robins’ behavior was right in front of me: my neighbor’s venerable holly tree. Covered with delicious—I suppose—red berries. They had crowded along its branches, gorging and perhaps getting a little tipsy if any of the berries were fermenting as sometimes happens. It was a grand party! No worries about social distancing. Maybe they were off to find another smorgasbord somewhere else in the neighborhood the next day, but there are still berries for the taking so I imagine they will be back. Still a cheerful sight!