Did You Know? Unsung Masters of Flight

by Jim Northrop, GSWA Volunteer

Geese in flight over NJ. Credit: Ann Campbell.

The other day I was walking in a local parking lot, when I heard a persistent honking in the sky. It was getting louder and louder. When I looked skyward, I saw a flight of large birds ---- perhaps 50 or 75 of them, passing overhead. What was most striking was not their quantity, but that they were arranged in a loose “V” formation. “Ah, Canada geese,” I said to myself.

Later, I was thinking about the beauty of that formation of Canada geese. I wondered why we normally see them flying in a “V” formation, so I decided to do a little research. Let me share with you what I learned.

The Canada goose (Branta canadensis) species is native to North America. It breeds in Canada and in the northern United States in a variety of habitats. Annually, the geese migrate south from Canada and the Great Lakes region, for the winter. In the spring, they return north. These annual migrations require them to be able to fly great distances.

The flight in “V” formation has been studied by various researchers. It appears that birds take turns in the lead position of the “V,” since flying in front consumes the most energy. Meanwhile, all the other birds in formation will position themselves in spots that are aerodynamically optimal ---- spots where they can take advantage of the swirls of upward moving air generated by the wing beats of the bird ahead.

Those swirls are very important. As each goose flaps to generate lift, small “whirlpools” of air rise to the right and to the left of the animal. By following one another the right way and timing their wing beats perfectly, each goose can ride the “whirlpools” created by the animal immediately in front of it. The result is a reduction in the amount of energy each bird must expend to gain lift in flight. Unfortunately, the lead bird gets no such lift advantage! And, if one bird happens to get a little too close or a little too far from the bird it is following, it instantly adjusts its wing beats to compensate. The same re-adjustment occurs when a goose chooses to change its position within the “V.”

Formation of Canada Geese.
Credit: flickr.com/donjd2 (Don DeBold)

How do the birds know to fly in these optimal spots? Researchers say that geese may have evolved “rules of thumb” for flying, or that they have “good sensors” and merely adjust to find spots that feel good. The up-wash of air that helps each bird support its own weight in flight, follows the same principles glider aircraft use to climb or maintain height indefinitely in rising air. Whenever a goose falls out of formation, it suddenly feels the drag and resistance of trying to go it alone. Very quickly, it returns to the formation to take advantage of the lifting power supplied by the other birds.

Anecdotally, it is said that when a goose gets sick, or is wounded by gunshot, two other geese will fall out of the “V” formation, follow the injured bird to the ground, and protect it from further harm. The guardians stay put until the ailing bird is able to fly again, or until their compatriot is dead. Eventually, if the trio returns to the air, they launch out in their own formation or join another flock until they catch up with their own group. This entire scenario may be a myth, but it is a lovely thought.

Researchers apparently have not attempted to calculate the energy a bird might save by flying in a “V” formation, but estimates range from a 30% energy savings to a savings of more than 70%. On long migration flights, Canada geese typically fly at about 40 mph. These noisy groups honk their way along established paths that include designated “rest stops.” Being social birds, they remain in flocks year round, except while nesting.

Scientists do not know how geese in flight find the aerodynamic sweet spot, but they suspect that the birds align themselves either by sight or by sensing air currents through their feathers. Alternatively, they may move around until they find the location with the least resistance. Other questions wait for future research. For instance, how do the geese decide who sets the course and the pace? Can a mistake made by the lead goose ripple through the rest of the flock and cause traffic jams? Whatever future research may tell us, we know already that Canada geese are very effective, amazing birds.

Did You Know? About Canada Geese

by Jim Northrop, GSWA Volunteer

Sometimes, fall walks with my dog surprise me. Last October, we walked along the edge of a local golf course. It was a beautiful, sunny day, but there were few golfers about. At a turn in the path, my dog saw something interesting and tried to take me to it. After a few steps, I saw that she had found a Canada goose resting in the long grass ----- the golf course “rough.” I stopped the dog, but the goose looked at us and did not move. Then, I swear, the goose spoke to me!

“I have been in flight for days, coming from mid-Ontario. I am not so young any more, and I don’t seem to have the energy of my youth. My mate was killed by a hunter last year, my goslings (her babies) are grown and doing their own thing, so here I am all alone.”

Who would not feel some pity at this story? The goose explained that she was part of a flight of 30 or 40 birds whose destination was Chesapeake Bay. She was glad they were not aiming to spend the winter in Mexico, as she was sure she did not have that distance in her.

“Why did you stop here?” I asked. They liked the available long grass in the rough, and the nearby water trap which were nicely placed within an easy walk. She felt safe, she said, because the only predators were occasional dogs, but she noted that even my dog was on a leash, as most “golf course dogs” seemed to be. This is a beautiful and peaceful place, she told me, except for the day when I was nearly hit by a golf ball, which brought several old men on golf carts to chase me from my nest. She said she realized they were looking for their golf ball, not for her. They had soon found the ball and moved on to complete their game.

I asked my new friend about her family.  Her male goose had been a wonderful father, she said. He would stand tall and guard her while she sat on a nest of eggs. What I would call the incubation period, in which the female sits on and warms the eggs while the male stands guard, lasts for 24 to 28 days after laying, she told me. She remembered how, after the eggs hatched, she and her mate would lead their goslings in a line, usually with one parent in front, and the other at the back. While protecting their goslings, she recalled, they often had to violently chase away threatening nearby creatures ---- anything from small blackbirds to large humans, who might approach. She and her mate would warn intruders by giving off a hissing sound and then attack with bites and slaps of their wings, if the threat did not retreat or actually seized a gosling. “Happily, that never happened to us,” she said.

She continued, “The goslings enter a ‘fledging’ stage any time from six to nine weeks of age. They do not leave their parents until after the spring migration, when they return to their birth place. Once they reach adulthood, she told me, Canada geese are rarely preyed upon (aside from the threat of humans). But the geese must be on the watch for coyotes, gray wolves, snowy owls, the golden eagle and the bald eagle.”

She surprised me by noting that goslings are able to swim immediately. The male and female geese both accompany their babies during their swims. She was proud to report that goslings can dive and swim for 30 or 40 feet underwater, and they eat almost continuously to attain growth for their first migration flight. The mature goslings, now ready for migration, learn the migration routes from their parents and follow the same route in subsequent years.

My friend stopped talking for a moment, and reflected that she had not heard of predators attacking her goose friends in New Jersey ---- except for the humans!  I had to tell my feathered friend that not all humans are a threat ----- many are friends, and keenly anticipate searching the sky in the spring or autumn at the first sound of honking Canada geese, flying by in their V-shaped formations. She said that was encouraging, and did I know that the front position is rotated among several birds since flying at the front consumes the most energy?

The sun was setting, and my dog and I were ready to return to our “nest” for dinner. We were sorry to leave our new goose friend, but she advised us she would be OK, and probably would resume flying south at sun rise.  We wished her safe travel.

Although often disparaged as a nuisance, we gained from this Canadian goose a new respect for these hearty birds, hoping that as long as they would stay away from airplanes in flight, they would continue to grace our open spaces.