The Swirl of Species

Sometimes the best way to witness the marvel of migration is to find a national park and just stay put.

By Jeff Rennicke

We live in a world of motion. John Muir knew it: “Everything is flowing—going somewhere… pulsed on and on forever like blood… in Nature’s warm heart.” Like flowing blood, motion means survival to most creatures. To stand still is to die. Call it the dance of life, the swirl of species.

There are many variations on the dance. For some it entails small steps: Elk climb to the high country in Rocky Mountain National Park to graze on new spring growth as the quilt of winter is pulled back. Katmai grizzlies zero in on Brooks Falls just as the first sockeye begin streaking the rivers like shooting stars. Horseshoe crabs click and clatter their way ashore on moonlit nights, laying their eggs in Cape Cod National Seashore.

Birds, animals, fish, and insects are moving around us all the time. But twice a year this swirl of species reaches a crescendo. Triggered by a slant of sunlight or dips in temperature, guided by inner compass bearings we hardly understand, millions of creatures are on the move each spring and fall in the grand spectacle of seasonal migration. Arctic terns stitch together continents with their wing beats on a 22,000-mile journey, the longest on Earth; humpback whales sound their way through the blue-black ocean depths. Wildlife biologists estimate that one-third of all the birds on the planet migrate—that’s 5.7 billion birds on the wing over North America, sometimes in flocks so immense they appear on radar screens.

Witnessing one such “wild circus” of migration—28,000 birds counted in one hour over Apostle Islands National Lakeshore—writer Michael Van Stappen wrote that “the overwhelming urge is not to ponder or wonder, not to linger or go home… in your heart the singular, deeply felt sense is to follow.”

Without the gift of wings or fins, it’s nearly impossible to follow. But within our national parks, which protect some of the most vital migration routes and stopovers on the planet, there are places where we can put ourselves in the path of this seasonal outpouring of life, look skyward, peer through the ocean depths, watch the horizons, and simply marvel.

Gates of the Arctic National Park & Preserve

The ground trembles, the air fills with low grunts and clicking hooves, and your tent suddenly resembles a boulder in a flash flood, surrounded by thousands of caribou cascading down a ridgeline. Or not. The migration in Alaska’s Gates of the Arctic National Park & Preserve is one of North America’s grandest wildlife experiences, but predicting it is a wilderness shell game.

Each year, the maze of mountain passes and valleys in this 7.2-million-acre park plays host to three different herds of caribou, including the 450,000 animals of the Western Arctic Caribou Herd, the state’s largest. The movement begins as a trickle in March, as females leave the wintering grounds on the tree-speckled southern slopes of the Brooks Range and wend their way north up the river valleys of the North Fork of the Koyukuk, the Alatna, and the John. Stitching their hoofprints in the snow, they cross high passes to the Colville and Killik, the Anaktuvuk and the Chandler, toward calving grounds farther west and north. Later, the bulls and yearlings will follow. Amid the first wildflowers, the females calve and join larger groups, which by early June begin moving into the foothills again to disperse for the short grace period of the Arctic summer. In the softening light of August, the herds gather again before returning to their wintering grounds, moving south across trails carved out by caribou that trod the very same ground over thousands of years.

It would seem difficult to miss the movement of nearly a half-million large animals, but this is raw wilderness, a “black-belt park” as one ranger has called it, without a single maintained hiking trail or campground. It is a land blessed with space, horizon after horizon of nameless valleys and passes. Just which pass the main herd will choose is a guessing game. Biologists, wilderness guides, and caribou watchers use radio telemetry, track herds with satellites, search with bush planes, and play their hunches. Still it is the wind direction, snow depth, forage, the presence of predators, and perhaps several unknown factors that set the rules. The best you can do is to guess, set your camp in a likely place, and hope.

To Carol Kasza of Arctic Treks, who has guided trips into Gates for 30 years, that’s just the way it should be. “To those who look carefully, the land is always alive with the signs of the animals who live here,” Kasza says. “If the timing is right and luck is with you, you can experience the ‘lifeblood’ of the Arctic—flowing rivers of caribou. Even if you don’t see that, you might be humbled as you ponder the palm-sized birds that fly from the other end of the Earth just to nest in this rich land.” It’s all a part of the dance of migration.

Big Bend National Park

The West Texas skyline cuts a rugged profile. Naked spires of the Chisos Mountains rise like claws from arroyos armed with the spears of cactus and agave. It can seem an unlikely place for a creature weighing less than half an ounce with a wispy four-inch wingspan as fragile and beautiful as stained glass. But the skies over Texas contain 442 species of butterflies, making it the most butterfly-rich state in the country. More than 170 of those species are found in Big Bend, including seven recorded nowhere else in the United States. One of the park’s highlights is the annual monarch migration.

With its familiar orange-and-black wing pattern, the monarch is one of the best known butterflies and the only one to undertake a long-distance, multi-generational migration. Each fall, millions of adult monarchs glide over North America, bobbing like musical notes on the breeze. Those west of the Continental Divide congregate in 300 sites along the coast of California, including Muir Woods National Monument and Golden Gate National Recreation Area. Eastern populations funnel through a 300-mile-wide swath of Texas known as the Central Flyway to gather in immense clusters in fir trees high in the transvolcanic mountain ranges of Mexico, sometimes hundreds of thousands on a single branch, passing the winter in a kind of suspended animation.

As spring approaches, these same butterflies begin to stir, mate, and drop to lower elevations. In mid-March, their wings tint the spring breeze orange and black as they leave the Mexican roosts to move north in search of milkweed plants to host their eggs. Once they’ve laid their eggs, the original migrants die, leaving the rest of the 2,500-mile journey to a succession of generations, each with a brief three- to five-week lifespan in which to hatch, grow, mate, and lay eggs themselves as they move north at 30 miles an hour, up to 80 miles a day, through the lengthening summer. As fall approaches, a longer-lived (six to eight months) generation is produced to migrate south, overwinter, and begin the process all over again.

Both spring and fall are good times to see monarch butterflies in Big Bend, which lies just west of the Central Flyway. In spring, migrants waft up from Mexico following the Rio Grande into the park and moving north through side creek canyons and low valleys. Monarchs need warmth and ride the sun-stirred thermals just as many migrating birds do, meaning the best times to look for them in the park are on warm spring days between 10 a.m. and 3 p.m., when temperatures are at their highest. In autumn, the fall migration begins in even more dramatic fashion with dozens of monarchs gathering on single plants within the park before being warmed by the sun and taking flight again to move on, connecting Big Bend to places far beyond on the fierce strength of their gossamer wings.

Point Reyes National Seashore

It’s hard to believe a creature that’s 40 feet long and weighs 35 tons can move through the water as easily as curved light, but watch the annual migration of gray whales at Point Reyes National Seashore and you’ll understand why “grace” is the only word that comes close to describing it.

The action begins far to the south in the warm, clear lagoons of Mexico’s Sea of Cortez, where female gray whales give birth to their 1,500-pound young, nursing them through the winter months on milk rich with 53 percent fat. By March, the young are strong enough to travel, and the whales move north toward feeding grounds off the Alaskan coast, a two- to three-month, 7,000-mile journey that is among the longest migrations of any mammal on the planet. And Point Reyes National Seashore is right in their way.

Jutting ten miles out into the Pacific Ocean, California’s largest peninsula is the perfect stage to witness the graceful passing of the gray whales. Once hunted nearly to extinction, gray whales now number more than 20,000. A large part of that population swims right past your eyes at Point Reyes. You can sign up for whale-watching boat tours with local outfitters, but you might be able to view them from tall cliffs on the water’s edge, or hike the 54 stairs down to the Sea Lion Overlook.

One of the best places on the peninsula for whale spotting is the Point Reyes Lighthouse. The first northward-bound whales—mostly males—appear in mid-March. Mothers and calves, which leave the wintering grounds later, appear closer to shore in late April and early May. It’s a slow parade. Unlike feeding humpbacks, gray whales only occasionally breach, although they often bob up and down in the water as if to look around—a behavior known as “spy hopping.” Mostly these gray giants simply dance a slow dance with the waves and the miles, maintaining a leisurely five-mile-per-hour pace, often in pairs that swim close to the surface, making them easy to spot. With a potential lifespan of 60 to 80 years and a journey that’s undertaken twice each year, a gray whale can swim nearly a million miles during its lifetime, every sweep of its tail the very definition of grace.

Jeff Rennicke is a teacher at Conserve School in Wisconsin's North Woods.

This article appears in the Winter 2008 issue.

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