500,000 Cranes Are Headed for Nebraska in One of Earth’s Greatest Migrations- page 2 | Science | Smithsonian
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500,000 Cranes Are Headed for Nebraska in One of Earth’s Greatest Migrations

At the end of March, 80 percent of the world’s cranes will converge upon one 80-mile stretch of land

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(Continued from page 1)

Traveling west from Lincoln on I-80, we begin to see masses of the stately birds in the rows of corn stubble flickering by. Ranging in height from three to four feet, they are moving on black stiltlike legs (their “knees” are modified heels, so they actually walk on their toes), with their necks bent down, stabbing at the stubble with long daggerlike beaks, flipping cow pies, crunching up insects, snails, frogs and snakes. The adults have bare red foreheads that expand when they are worked up and compact feathers covering their ovoid torsos—except for their bustles, the loosely stacked tips of their wing feathers that extend past the short tail and flare up when they are agitated.

Not only the cranes, but some 20 million other migrating birds belonging to 300 or so species stop over on the Platte, including 280 of the remaining whooping cranes, 90 percent of the white-fronted geese that ply the midcontinent, thousands of endangered piping plovers, 30 percent of the northern pintails, 50 percent of the mallards, as well as bald eagles and some two million snow geese. Soon after we travel under Kearney’s Gateway (to the Great Plains) Arch, we pass a depression—an old borrow pit—smothered with maybe 20,000 milling snow geese, like a blanket of snow. The geese come earlier than the cranes and clean out many of the cornfields near the river, but there is plenty of waste grain in the central Platte valley to go around. Michael Forsberg, a Lincoln-based wildlife photographer, calls this stretch of the Platte “the pinch in the hourglass” for all these converging northbound migrants.

To Forsberg, the sandhill crane is the ambassador of the plains. Some 70,000 crane watchers flock to the Platte annually, last year from every state in the union and 47 foreign countries, injecting $11 million into the local economy. People tend to think of Nebraska as a fly-over or drive-through state, he says, but there is incredible beauty, only it’s subtle—except when the cranes are here.

Crane-watching consists mainly of taking in three activities: when they wake up and take off from the sandbars on the rivers, when they come back to them to roost, and during the day when they are out foraging in the cornfields and doing their dances. The most popular place to see the sandhills on the river is the National Audubon Society’s Rowe Sanctuary in Gibbon, just outside Fort Kearney. One morning at 5, I tiptoe into a viewers’ blind at Rowe with a score of other tourists and we station ourselves and our cameras at its little windows. No flash or LED lights are allowed. It is bitter cold, ten degrees with the windchill. As day begins to break, we see that a 100-foot channel of the river, with shards of ice on its surface, is gliding silently by right below us. Its pebbly bottom is only a foot or two down. Across the channel is a sandbar on which the faint gray forms of several thousand lesser sandhills, still sleeping on their feet with heads tucked under a wing, become increasingly apparent. They are headed to the Kuskokwim Delta in the Yukon and western Alaska, some all the way to Chukotka, in eastern Siberia. The smaller the crane, the farther it flies to its nesting grounds, and the shorter and more needle-line its beak.

The midcontinental sandhill population has four “breeding affiliations,” two of which overlap. This was discovered by Gary Krapu, a wildlife biologist with the United States Geological Survey, who netted and tagged 153 sandhills on different stretches of the Platte and satellite-tracked them from l998 to 2003. Most cranes take over the same section of river each year. This is not unique to cranes. We have a yellow-bellied sapsucker that returns to our cabin in the Adirondacks each spring from wherever in Central America or the Caribbean it wintered and drives us crazy drilling on the roof to attract a mate. The bigger cranes, from the other affiliations, have staked out the sandbars downstream, all the way to Wood River. Some are headed to Hudson Bay and the Canadian boreal, with its mazes of bogs and muskeg to nest in.

George Archibald, the co-founder of the International Crane Foundation, thinks the first ancestral cranes were likely from the New World. The crane’s closest relative is the limpkin, a New World tropical wading bird. Crowned cranes, the oldest lineage of Gruidae, radiated to Africa, where the only two species survive. Fifteen-million-year-old crowned crane eggs and a skeleton have been found in northeastern Nebraska. According to the fossil record, the sandhill migration has been going on for millions of years. “During the ice ages their range was constricted, and as the ice retreated to the north they developed these long migrations,” explains Archibald. “They followed the ice north. Nebraska is at the southern edge of the last glaciation. What they may have been doing during previous interglacials there is no way of knowing.” To this day, cranes are often described as birds that “follow the edge of winter.”

The cranes on the sandbar begin to stir and purr contentedly. They sound like a chorus of drawn-out rolled French r’s, like their French name, grue, and their English one, “crane,” from the Proto-Indo-European gerh, meaning to cry hoarsely. Some of the cranes step out into the water.

Margery Nicolson, an elderly woman who is volunteering as a docent, whispers to me, “Around the bend, it’s packed solid with cranes for a mile upriver. The white-cheeks are the adults.” Nicolson comes every year from Pacific Palisades in Los Angeles to be with the cranes. The visitor center is named for her late husband. Another docent, volunteering from Tucson, whispers to a couple taking in their first cranes, “They start coming on Valentine’s Day and leave in time to pay their taxes.”

The murmur of contentment, the fricative purr, spreads among the cranes and grows louder. Some of them begin to flap their wings, whose underside tips are black, and a contagious frisson of flapping and rolled r’s ripples through the flock, particularly along its edges, where the hormonally pumped adolescent colts are. (For some reason crane nomenclature is borrowed from horse terms. A mother crane is called a mare, the dads are roans. The terminology sounds like it was created out West.) A male starts braying, likely calling for its mate. The collective purr is punctuated by unison calls between bonded pairs, during which the male points his bill straight up to the sky and the usually shorter female points hers at a 45-degree angle and gets in twice as many (and higher-pitched) calls as he does.

When the sun hits the flock and turns it gold, they all take off, peeling out in extended-family groups of 15 to 40, fanning out in every direction—except for scattered maverick late risers and one that Nicolson picks up in her binoculars that is lying down. “It must be injured,” she whispers. “That guy’s a goner, I’m afraid.” Two bald eagles are perched in a cottonwood tree a few hundred yards upstream. They will not fail to spot the injured bird and make quick work of him.

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About Alex Shoumatoff
Alex Shoumatoff

Alex Shoumatoff is working on his eleventh book, about Borneo, and is launching a documentary series titled Suitcase on the Loose. Like his website, the series is dedicated to making people aware of and care about our rapidly disappearing natural and cultural diversity. He last wrote for Smithsonian in 1978, about the reintroduction of peregrine falcons.

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