“V’s” of migrating Canada Geese are a common sight and sound in the Northeast during October. The inevitable question arises: why fly in a V formation? In part, because it conserves energy. But exactly how does it do this?
As the lead goose flaps, it creates tiny vortexes (circular patterns of rotating air) swirling off its wings as well as into the space behind it. The vortex behind a goose goes downward, while the vortexes on either side of its wings go up. If a goose flies directly behind the goose in front of it, air will be pushing it down. If it flies off to the outer side of the goose in front of it, air is pushing upward and the goose will get a slight lift, making flying easier.
Picture two geese flying behind and to the outer sides of the lead goose. Additional geese, in order to avoid the vortex behind the lead goose as well as the vortexes directly behind the next two geese, will fly behind and to the outside of the wings of the two birds in front of them, getting a lift and forming a “V.”
Because the lead goose has no vortex to get a lift from, it tires more easily than the other geese. It periodically falls back and is replaced by another goose in the formation. This cooperative process of taking turns leading the flock minimizes the need for the birds to stop and rest.
My apologies to the 50+/- NC readers who responded with great creativity to the latest Mystery Photo! The photographer and I had a miscommunication, and I misdirected readers about the actual mystery you were to solve! I thought the photographer had observed a goose making the two parallel lines in the ice with their feet (nails) as they landed. However, these two lines are actually just cracks in the ice, as many readers guessed (Susan Cloutier was the first to correctly identify them). While Canada Geese do use their feet as well as their wings as brakes to slow themselves down before they land and they do have a hind toe which conceivably could scratch the ice, the landing imprints of the geese (and what I should have asked readers to identify) are actually in the upper half of the photo (see red circle) where the snow has been plowed aside, revealing the darker ice underneath. The presence of a considerable amount of goose droppings confirms the identity of the birds landing on the ice.
Observers often ask how Canada Geese or other waterfowl can stand for long periods of time on frozen lakes and ponds.The legs and feet of waterfowl play an important part in maintaining their body temperature. In the summer, their large, flat feet cool their body by releasing a good deal of heat. In winter, the heat exchange system (counter-current circulation) in a bird’s legs prevents a great deal of body heat loss due to the fact that the warm arterial blood going into the bird’s feet is cooled by the colder blood traveling back to the body in adjacent veins. Constricted blood vessels in their legs further conserves heat. (Photo by Mike Hebb)
It’s common knowledge that birds periodically turn their eggs when they are incubating them, but have you ever stopped to ask why they do this. One assumes that if this action weren’t critical to the incubation process, it wouldn’t be practiced, and science bears this out. According to Audubon, birds turn their eggs to make sure the embryo gets enough albumen – the white part of the egg that contains water and protein and provides essential nutrients to the developing embryo. Too little albumen leads to an underdeveloped and often sickly chick. (Photo: Canada Goose turning eggs)
If you are fortunate enough to have a beaver pond near you, you should give the lodge more than a cursory glance this time of year. It is common to find Canada Geese nesting on beaver lodges, for obvious reasons – safety from most land predators. While Common ravens have been known to raid Canada Goose nests for eggs and goslings, the overall rate of survival of the goslings of lodge-nesting geese is very high.
A Canadian study showed that ponds with beaver lodges (and therefore Beaver activity which warms the water and thaws the ice) thaw at least 11 days sooner than ponds without Beavers, allowing early access to water for Canada Geese returning for the spring nesting season. Battles between pairs of geese vying for these coveted nesting sites are not uncommon.
Canada Geese have much to thank Beavers for. Not only can geese get an early nesting start on beaver lodges, they have a relatively safe spot to incubate their eggs and raise their young.
Within 24 hours of hatching, downy Canada Goose goslings leave their nest and are capable of walking, swimming, diving and feeding themselves. Like many species of waterfowl, their growth is rapid. Contour feathers on their wings and tail begin to emerge in about three weeks (note wing feathers of gosling in photo). Feathers on a gosling’s head, neck and back are the last to appear. Just before a gosling develops the ability to fly, the last fluff of down, which is on top of its head, disappears.
During migration and throughout the winter, Canada Geese are highly gregarious, often gathering and feeding in flocks that consist of over a thousand geese. Almost exclusively herbivorous, they are efficient grazers, having serrations on their stout, flat bills. During summer they feed primarily on grasses and sedges. Considered a nuisance by many people with large lawns Canada Geese are attracted to these lawns not only because they can digest grass, but also because they have an unobstructed view that allows them to detect approaching predators. During and following migration, berries (especially blueberries) and agricultural grains including sorghum, corn and winter wheat make up most of their diet. When you see them in cornfields, they are feeding on fallen kernels as well as corn still on dry cobs — they are very good at removing the kernels.