Nature Notes: The Behavior of Birds
The great American winter pastime for those of us who live not too far from the Arctic Circle: feeding and watching birds. Each bird species has its own unique way of staying active when the windchills are in the single digits and the sun is covered up by a pale gray sky for most of the day.
If you’re a bird, in order to generate body heat when there is no external source of heat to draw from, you have to stay active. Fly back and forth with a great flurry of extra wing movements, move over the terrain hither and yon, never stand still for more than a few seconds at a time (except at night in some protected niche), and one more thing: feed, feed, feed. Eat all you can. The more grist for the mill, the more heat for the body, the better the chances of survival in a winter such as this one.
The behavior of birds, more than that of any other kind of animal save humans and livestock, is responsible for the rise in the scientific discipline ethology — to some of us, wildlife behavior, to others, animal psychology. Its origin is European. Aristotle in the early B.C. years observed bird behavior, as did a host of early naturalists, but before it became a true science it needed some help from the likes of Niko Tinbergen and Konrad Lorenz of the old continent.
American naturalists were particularly interested in bird behavior early on. In the early 1900s in this country, a group of birders studied this and that bird species and charted their collective observations in a series of monographs. Hunters were also keen on bird behavior. How does the flush of a quail differ from that of a pheasant or a ruffed grouse? What ducks approach decoys low over the water, what ones come in high over your shoulder, then descend rapidly? How different birds fly was part of the general hunting lore. How much do you lead the fast-flying canvasback duck or the laggardly, lumbering Canada goose?
Snakes move by sinusoidal movements of the body, reptiles and salamanders by putting one foot after the other, frogs and toads swim, or jump and hop, turtles plod. Bird locomotion is highly specialized, just as mammalian locomotion is, and differs dramatically from one bird group to another. Since almost all birds flock at one time or another in their lifetime, a species has to know its own flight pattern; otherwise it is liable to wander off with the wrong group.
Roger Tory Peterson was very keen on bird flight types; his bird silhouettes on the inside covers of his bird field guides reflected that interest.
Woodpeckers, including flickers, move up with each sweep of the wings, down with each glide. Thus they are one of the very distinct up-and-down fliers that can be recognized from a long way off. Goldfinches fly similarly, while mourning doves fly in a beeline with rapid wing movements, such that they whistle when taking off or in straight-line flight, perhaps a warning signal with respect to predators. Herons have very large wings and oscillate them very slowly and glide a lot between strokes, with their long necks in a tight S shape, the long spear-like beak projecting forward only slightly beyond the bend of the neck.
Other long-necked birds like cranes and bitterns extend their heads and necks fully forward in flight. The brown pelican flies in small family groups of five or six, one after another in a straight line. When the leader stops flapping, the followers also cease in precise succession, and the group glides for a spell. When the leader decides to stop gliding and start flying, the followers pick up the beat one after the other with the same synchronicity.
Some hunting birds such as kingfishers, rough-legged hawks, kestrels, and kites are capable of hovering in place for minutes at a time as they try to get a precise fix on their prey below. They beat their wings rapidly and curl them accordingly while doing so. Some birds, such as vultures, ravens, and gulls, are capable of long flights while barely beating their wings at all. Thus they conserve energy for other uses. Some hummingbirds common in the Northeast beat their wings more than 50 times per second in order to keep in place while sucking up nectar from a tubular flower.
Some birds use flight for dual purposes — getting around and courting. The American woodcock male makes circles over the female hiding in the bush, then drops down with a bunch of piped notes to where she sits for mating. The European skylark, as in Shelley’s poem, does its territorial singing and courting from above, not from aside. Our local swan, the mute swan, is not much of a vocalist, but when it flies overhead it sounds like a World War II bomber, whomp, whomp, whomp, whomp, and so on. The American goldeneye duck sings with it wings. As a group of them fly over the water, they beat their wings in synchronicity, producing a monotonal chord that is both melodic and comforting to the listener on the shore.
“Birds of a feather flock together.” That old saw clearly plays homage to the importance of the uniqueness of bird flight and species recognition.
The shape of birds in flight as seen from the ground by other birds is important, as well. Hawks have a longish tail and shortish head and neck. The falcon silhouette, as seen from below, is rather typical of most hawks. Geese and ducks, on the other hand, have long protruding necks and short tails in flight. When Lorenz, using two-dimensional goose silhouettes, moved them forward on guide strings over baby chicks, the chicks were not alarmed and went on feeding. When he moved them tail first, they appeared hawk-like, and the same chicks scattered.
You may have noticed, also, that the way birds move over the ground is somewhat species-specific. Robins hop, two feet side-by-side at a time, for short distances, then stop, motionless. Mourning doves walk one foot after the other, rapidly. Quails scurry, with bodies almost hugging the ground. Roadrunners, which are perfectly capable of strong flight, run with quick long strides, in the manner of the ratites, the ostriches, emus, and rheas, which are flightless. Sparrows both hop and walk. Almost all shorebirds walk, or run, one foot after another, as they descend and rise with the coming and going of each wave swash. Crows, wild turkeys, and pheasants are also walkers, not hoppers.
The way birds feed can differ according to species. Starlings peck ravenously. Titmice pick up a large seeds and fly off with them, land on a branch, then work them over with their beaks while holding them in place securely with their feet. On Saturday, the winter robins, not those back from the south yet, were on the top of the cab of my black pickup parked at the end of the driveway next to the leafless hedges on either side. They were working away at something. When I went to look later on, the top of the cab was covered with half-eaten black privet berries, seeds partially exposed, not the robins’ favorite food stock by any means, but the only berries left in the vicinity at this time of year.
Larry Penny can be reached via email at [email protected].