Winging South

October-November 2006

This is an article from WaveLength Magazine, available in print in North America and globally on the web.
To download a pdf copy of the magazine click here: > DOWNLOAD

by Neil Schulman

It’s a cold, wet, dreary winter. So you head for a week of paddling in sunny Belize or Baja. You’re on the plane, half dozing, half watching the in-flight movie, when something taps on your window.

You look out and see a brown, mid-sized bird with long legs and a long, curved bill. It’s a Long-billed Curlew, and it’s tapping on the window because it wants in. It’s going to the same place you are.

Every year, paddlers spend big bucks to fly to more hospitable waters. So do millions of birds, but they do it without jet planes, aviation fuel, maps, or weather forecasts. The idea of seeing a curlew from a 727 is not entirely crazy—many birds migrate at the cruising altitude of jetliners. While we think it’s novel to head for the tropics in winter, we’re really just following wingbeats that have gone before for millions of years.

WHY MIGRATE?
For anyone who endures northern winters, this seems like a dumb question—it gets downright cold and dark up here. But bird migration is more complicated than just craving sunshine and a warm beach. In fact, migration isn’t always a question of north to breed, south to winter. Varied Thrushes (a relative of the robin) are vertical migrants. They winter on the coast, and in summer move up the slopes of the Cascades and Coast mountains to breed. Spectacled Eiders—migrate north in winter. (More about them later.) Migration is a careful balancing of delicate evolutionary factors—food, predators and the risks of the journey.

THE COSTS
When you look at what birds do, it’s hard to understand why migration could be worth it. Curlews fly from the prairies of Alberta, Montana, Washington and Oregon to Central America. Hummingbirds smaller than ping-pong balls brave the wide-open Gulf of Mexico. Godwits leave the Aleutian Islands and fly—in one single, 7,000 mile continuous flight—to Fiji or New Zealand. Bar-headed geese cross Everest twice a year. Grouse migrate up and down mountains—by walking. Swainson’s Hawks fly the length of two continents to the Pampas in Argentina.

It’s all phenomenally risky. One spring storm over the Gulf of Mexico will drown hundreds of thousands of northbound birds. Missing a key stopover for food will cost a bird its life. Millions succumb to weather, predators, get lost or simply run out of steam.
Metabolically, migration is also one of the most expensive things a bird can do. The energy output is astronomical. Migrating birds routinely burn 55% of their body weight. By the time they finish long crossings they’re literally starving—metabolizing the muscles they use for flight—in a last attempt to make it. Then they undertake the other metabolically expensive activity: breeding and raising young. Why not just stay put in the tropics?

WHY IT’S WORTH IT
In my entire North American bird guide, there are 44 species of warblers listed. There are more than that on the seven islands of Puerto Rico and the Virgin Islands alone. That’s part of the answer.

The tropics have the greatest assemblage of diversity on earth—everyone’s competing for food and space. During breeding season, the competition for food is even more intense, because eking out a living is tougher when everyone has kids to feed. In contrast, take the Canadian arctic. There the sun shines all summer long, 24 hours a day—sparking intense growth of vegetation that creates seeds and berries cramming all their productivity into a few short months. The melting permafrost creates ponds, which breed insects by the million. If you can manage the trip, it’s an all-you-can eat buffet for both hungry migrants and hungry kids.

And the arctic tundra is largely devoid of nest predators—a major risk of raising kids in the tropics. Sure, there are some arctic foxes and ravens, but nothing near the number of climbing and crawling nest predators in the Amazon. Lack of nest predation is a major incentive to migrate.

BROTHER, CAN YOU SPARE A STORM? A MAP? SOME EXTRA FAT?
Unlike kayakers, migrating birds aren’t afraid of strong winds. In fact, they need them. Shorebirds heading south from Alaska will become more active when the wind starts to blow—they look for the first storms of winter to give them a solid push south, sometimes at amazingly high altitudes. They’ll fly as high as they can—high enough to tap on the window of your airplane. The north winds from the first winter storms make the giant single flights over the sea possible.

But what’s truly astounding is that most birds do their first migration entirely on their own. The exceptions are ducks and geese, which travel in family groups. Shorebirds first put all the kids in giant, multi-species ‘day care areas’ where a few adults can watch for predators while the rest start gorging. Then the adults take off, leaving a few weeks before the kids can fly. The kids—navigating thousands of unseen miles based on a secret genetic map—still somehow make it on their own.

To fly those miles, amazing changes must first kick in. Neural patterns change to increase appetite so birds can put on as much fat as possible. Feathers lengthen, and the intestinal tract atrophies to lighten its weight. Small changes, but heck, if I were a hummingbird flying across the Gulf of Mexico, I’d want them too.

FORGET THE FLYWAY
In middle school, I learned about flyways: migratory highways heading up both coasts of North America, one up the western states and provinces, and one up the Mississippi River and the prairie provinces. This concept works for predicting the movements of ducks, geese and a few other species, but is otherwise a gross oversimplification. Birds are really zipping around every which way, both horizontally and vertically. Godwits fly southwest from Alaska to New Zealand across the wide Pacific. Arctic Terns are famous for going pole to pole—but they do it by zigzagging across the Atlantic to Europe, down the coast to Africa, and then back southwest across the Atlantic to South Georgia and Antarctica. Blackpoll warblers fly east from western Canada across the boreal forest to the Maritimes, and then arc south over the entire open Atlantic to Venezuela. An American golden plover will fly from Nova Scotia to South America via 2,400 ocean miles instead of following the coast. And he’ll be there in 48 hours.

MELDING WITH MIGRATION
If you want to get the feel of migration, here are a few birding experiences that will knock your socks off.

Feel the Spray
Between March and May, go to a jetty that sticks out in the open sea. A stormy day with a south or southwest wind is best. Dress warmly. Walk out to the end and sit still for a while. Watch birds zipping by, heading one way—north. Even better, get on a boat that’s going well offshore—Shearwaters, Sabine’s gulls, and others migrate far offshore where we can’t usually see them.

Follow the Funnel
Raptor migration is best on sunny fall afternoons. Raptors migrate by finding tall ridges where the warm air rises. They soar as high as they can, then glide to the next ridge, all the way to South America. Where the ridges funnel to a narrow point, astounding numbers of birds go by every day. HawkWatch International monitors trends in hawk populations at key spots like Chelan Ridge, Washington, the Goshute Mountains in Nevada, and Bonny Butte near Portland, Oregon. Many are open to visitors (bring treats for the bird counters and banders). The best funnel point is where Mexico reaches its narrowest point near the town of Veracruz. The entire world population of Swainson’s Hawks and Mississippi Kites are counted from the roof of the tallest hotel in town.

Fallout
Tiny birds crossing the great, wide ocean is the most daring feat on the planet. The feeding frenzy that follows is one of the most spectacular. Flocks of warblers hit land and begin eating like fiends. The most famous fallout spots are the Gulf Coast of the US and the area around Point Pelee, Ontario, on the Great Lakes. Fallout is exactly what it sounds like—massive flocks of warblers and other small birds dropping out of the sky, devouring everything they can find with no regard to humans. If you want a mosquito plucked right off your nose, this is the place to be when the timing is right.

Mystery and Awe
We’re still learning huge amounts about migration. Until the mid-1990s, nobody knew where Spectacled Eiders (an arctic sea duck) went in the winter. Nobody had ever seen one in winter, until GPS became available. A signal came from a tagged eider, far north in the frozen Arctic Ocean. From a plane, researchers saw more than 150,000 eiders in a hole in the sea ice, happily swimming around in minus-30 degree weather.

When you’re paddling in Baja and spot some Brown Pelicans diving for fish, don’t be surprised if one of them looks at you like he recognizes you. He probably does—from summer on either the Northwest or Northeast coasts. Just remember, he got here without a plane or a map.

GOOD READING:
Living On The Wind: Across the Hemisphere With Migrating Birds by Scott Weidensaul, North Point Press, 1999

GOOD VIEWING:
Winged Migration by Sony Pictures, 2003

GOOD FOLKS:
HawkWatch International www.hawkwatch.org

© Neil Schulman doesn’t migrate south very often. But he’s envious of his friends, human and avian, who do.