When a bird flaps its wings it disturbs the air, leaving behind eddies that move invisibly in the air like the waves from a motor boat spreading out in the water in a big V.
Some gregarious species, such as the Canada goose, have learned to take advantage of the upward disturbed air created off the wings of the flock by flying in a wedge or V formation. Each bird thus adds the lift lost by the bird ahead to its own.
This drafting allows the geese to fly at an easier pace. Researchers have found that geese flying in Vs can journey as much as 70 percent farther than they would otherwise.
When traveling long distances, tundra swans fly in the same V-shaped formation as geese and for the same reason. The air resistance is less as each bird flies in the widening wake of its predecessor.
The leader has the hardest work, blazing the trail. Much like a pack of cyclists, the flock will fracture its formation over time and reassemble a short distance beyond with a different individual at the head of the flock.
Canada geese and tundra swans are not the only birds observed traveling in V or wedge-shaped patterns. Other species of swans and geese — plus ducks, cormorants, shorebirds and gulls — also arrange in that model.
During October and throughout most of November, I enjoy watching at sunset as one V formation after another of Franklin's gulls makes its way to Lake Waconia, where these social birds will spend the night as a giant surface water flock.
Jim Gilbert's Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. His observations have been part of the Minnesota Weatherguide Environment Calendars since 1977, and he is the author of five books on nature in Minnesota. He taught and worked as a naturalist for 50 years.
