For the Birds Radio Program: November Robins
As October moves into November, robins quickly disappear from the northern landscape. A few flocks are still hanging on in mountain ash, crabapple, and other fruit trees, but most have moved south, pressed on by an inner urge far more compelling than switching from Daylight Savings Time. In spring, robins fly in along the 37 or 38 degree isotherm, impelled northward the moment the weather allows. In fall, without the hormonal imperatives of breeding and territoriality, they’re not in such a rush—they wend their way south capitalizing on late summer and early fall’s abundant fruit, worms, and insects. Their haste as October draws to a close is as much from depleting fruit supplies as from cold fronts, though they do take advantage of tail winds to make their biggest flights when the wind is from the north.
Robins are such homey, common birds that we take them for granted when they’re wonderfully adaptable birds, found throughout much of North America including southwestern deserts and high mountains. To survive and even thrive at high elevations, mountain robins develop larger hearts and lungs than others of their species—robins living at 9,000 feet have lungs 41 percent larger than the lungs of those living at sea level.
Robins adapted to human habitations mainly because our lawns, at least before pesticides, were rich in earthworms. We get so accustomed to seeing robins in our backyards that we often don’t even notice them in the Boundary Waters or other forested regions. Sometimes when we do see one in a wild area, we don’t even recognize it at first glance, because robins who live in unsettled areas are wild and wary, skulking about rather than boldly running across lawns.
Although robins are still taking a few worms here and there, the bulk of their diet is within trees now, so we only notice them if we’re looking up and paying attention. More and more of the ones we see now aren’t our good old Midwestern robins—as the season progresses, ours are replaced by robins from the far north, which we can recognize by their more intense colors. In particular, I always notice the black-and-white striping of the throat in these northern robins. Males of the northern race often overwinter, and their vivid markings are especially pleasing when they fluff out in snow-covered branches. They easily get by, even in a severe winter, on a diet of berries. As long as the food holds out, they don’t have any problems with the cold, growing thick down feathers to keep them well insulated.
Some songbirds defend a winter territory as well as one on their breeding grounds, but not robins. The ones that remain here often collect in small flocks even in the dead of winter, and ones that go farther south congregate in huge ones—in the Great Dismal Swamp of Virginia, winter flocks have numbered over a million. Last week the Wisconsin bird chat on the internet reported a roost in Monroe County of up to 5300 robins, and another in La Crosse County with about 3000. These enormous groups are not nearly as welcome as the first robin of spring, consuming enormous quantities of fruit that was sometimes cultivated for humans, making the birds very unpopular with the farmers. The word “robin” originated as an affectionate nickname of the name Robert, but fruit growers in the central and southern states may well believe it comes from these avian pigs robbin’ their crops. Of course, the robins don’t see it that way—food is food, there for the taking. As with many issues between humans and wildlife, it’s all a matter of point of view.