Bird Watcher's General Store

Migration Part Two

I know I wrote about bird migration last week, but I was too distracted watching the Emmy Awards to finish. Here's a few things that I didn't get to and then I'm done with it for good, maybe.

In the north, creatures that don't migrate either have to endure long periods of frigid weather or hibernate like bears. The problem with hibernation is that, the ones that do it, miss out on all those great winter holidays. Migration is really the way to go. Migrants can enjoy life 365 day a year. But migration isn't an option for all creatures. And lucky for us it isn't. Florida has enough trouble right now without dealing with thousands of Grizzly Bears looking for a place to hang for the winter.

Bird migration is as diverse as it is amazing. The lazy cardinal pretty much stays in the same area year round. Birds like Snowy Owls only migrate when there is a shortage of food. While others like Bobolinks can't get far enough away from here. They fly all the way down to Argentina.

The most ambitious bird of them all is the Arctic Tern. This small tern, which mostly nests in the high Arctic, with a few nesting here on Cape Cod, likes to spend its winters way down in Antarctica. In the late summer it leaves North America for its long journey south. You would think, to save time and energy, it would head directly south. But nooo! Instead, this crazy bird flies east, way east, all the way across the ocean to Europe. Then it works its way along the coast to Africa and finally on to Antarctica. By the time the tern returns in the spring, it will have flown nearly 35,405 kilometers. I'm not really sure how far that is in miles, but I'd bet it's a lot.

Equally as diverse is the time of day that birds make their flights. There are birds that will only travel at night, some that will only fly during the daytime and others that don't seem to care when they fly. Most songbirds fly at night, which is unusual since the rest of the year they don't fly after sunset. The cover of darkness protects them from songbird loving hawks and falcons. Birds of prey, on the other hand, migrate during the day. They depend on the heat of the sun to warm up pockets of air called "thermals". Hawks can soar on thermals for miles without flapping a wing. Ducks and geese migrate either day or night, probably depending on the amount of coffee they drank at breakfast.

Night time songbird migration fooled many early scientists. Since the birds were there one day and gone the next, they figured that the birds must be hibernating nearby in some secret underground location. Other naturalists believed that birds would simply fly off to the moon for the winter. The moon? I wonder what those guys were smoking? For years many thought that hummingbirds were not strong enough to fly across the Gulf of Mexico on their own. They believed that hummingbirds rode across the gulf on the backs of larger birds like cranes or geese. Can you imagine flying across the gulf on the back of a goose. The honking alone would make the hummers wish they had taken the bus.

The combination of length of day, temperature and weather are the major factors that trigger migration. When all of the conditions line up just right, the birds make their move. Huge waves of them go for it at the same time. Radar has detected as many as fifteen million birds flying over Cape Cod on a single fall night. Can you imagine 15,000,000 birds overhead? That would be the wrong night to forget to take your laundry in off the clothesline.

For those of you who don't have your own radar, here is something fun you can try. About 11:00 PM, on a clear moonlit September night, focus your spotting scope (binos might work too) on the moon. You'll be surprised how many birds you will see blasting past the moon on their way south. (That's "past" the moon, not to it.) I tried this last year and it actually worked. I could see hundreds of silhouettes, thousands of feet up in the night sky, racing towards a very distant destination. The next full moon is this Tuesday, for anyone who actually cares. If the birds don't show up and you get bored, you can always use your spotting scope to see what your neighbor is doing after 11:00 at night.

Artwork by Catherine Clark

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