Vees in the sky

Those vees of migrating birds are a lovely sight as they slide across the pale blue sky in these crisp, crystal-clear days of early fall. Sometimes they fly in perfect lines, straight as an arrow. Other formations are still shaping up, the lines a bit wobbly, with maybe a lone straggler frantically flapping its wings as it tries to catch up.

These days we watch in wonder at one of the miracles of nature. The vees are an inspiring sight, but they raise questions, too.

Q. Why the vee?

A. The lead bird, a powerful individual, cuts the wind and makes flying easier for the two on each side. The same thing works back along both sides of the vee.

Q. Which species fly in the vees we see here in Eastern and Downeast Maine?

A. Mostly waterfowl, ducks and two kinds of geese, Canadas and brant (as with sheep, the plural of brant has no “s”). Shore birds, such as plovers and sandpipers, are smaller and fly at lower altitudes, so they don’t need a windbreaker ahead of them. They don’t form vees.

Q. Where did they come from, and where are they going?

A. Many of them summer in the arctic and subarctic and fly to the southern states, Mexico and South America. Brant with light-colored bellies pass through Maine, while those with black bellies often winter on the West Coast.

Q. How do they know where to go, and how do they find their way back in the spring?

A. Just like Columbus, they rely primarily on the North Star, the only star that that stays in place all night. They fly away from the North Star in the fall and toward it in the spring. A back-up system seems to be a concentation of magnetite, an iron ore, in their brains, so that they can detect the strength and direction of earth magnetism. (Columbus used magnetite, too, in the form of a lodestone compass. 4/5

Q. How do we know about magnetite in birds?

A. Biologists have found it in the brains of pigeons, explaining the directional skill of carrier pigeons. Also in the bobolink, known as a long-distance flyer. A British researcher maintains that humans carry magnetite and can detect earth magnetism, possibly explaining long-distance migrations of primitive peoples in prehistoric times.

Q. Do migrating birds ever make a mistake and fly the wrong way?

A. Absolutely. A stormy fall in the 1940s caused a European robin-like bird called the fieldfare to wind up in Greenland, where it established a permanent colony. And milder winters and a wrong turn in the 1940s and 1950s caused a little warbler called the blackcap to settle in England instead of migrating to Africa.

Q. How long does it take the birds to make the trip?

A. Days or in some cases weeks.

Q. Do they stop en route to eat and sleep?

A. Generally yes, so stopover areas in wetlands and shorelands are essential. But plovers and sandpipers must fly nonstop to Africa. A little warbler called the blackpoll (which weighs only 12 grams – about as much as two nickels) flies four or five days nonstop to South America. In preparation, it eats a lot and triples its weight in two or three days. It starts out as just a little ball of fat. Unlike airline pilots, some birds can “sleep” while they are flying at night, by shutting down about half of their brain activity and flying on a sort of automatic pilot system. Scientists don’t yet know how this works.

Next time you see one of those vees, you can thank Dr. Rebecca Holberton, an assistant professor of biology at the University of Maine, for the above information. She is an endocrinologist specializing in bird migration.