Each spring people
from across the country and around the globe flock to Nebraska's
Platte River to marvel at one of the bird world's most spectacular
phenomena. As half a million sandhill cranes converge during their
northward migration, they overcome staggering human challenges while
reminding us of nature's resilience.
Frank Graham Jr.
As the March day drew to a close, two dozen watchers peered through small openings in a long wooden bird blind on the shore of Nebraska's Platte River. “They're coming in bigger flocks now,” a man said softly, but with a hint of rising excitement. The long-necked cranes sailed on broad wings against a sky whose gathering darkness was slashed in the west by a garish wedge of sunset. Slowing and descending now on wings arced tentlike over their bodies—dumping the wind from their wings, as it were—the cranes wobbled in the air once or twice and, in a volley of piercing, rattling calls, dropped into a wet meadow within sight of the blind. One of the grandest cyclic phenomena on our continent was at full tide.
Waves of wood warblers make their way north through hardwood forests in May. Bursts of wildflowers ignite western mountain meadows with color in summer. Each recurring natural event marks our personal calendars. But the concentration for a few weeks in late winter and early spring of vast numbers of what is perhaps the world's most ancient avian group, along a river's 80-mile stretch, is unique. As half a million sandhill cranes funnel in spring migration through the central Platte, their human admirers come to gaze and almost babble. Hushed expressions of awe are common at the spectacle of massed but graceful flight and the resonant calls that may have been sounded in this part of the planet 9 million years ago.
“When we hear his call we hear no mere bird,” Aldo Leopold wrote of the sandhill crane in A Sand County Almanac. “We hear the trumpet in the orchestra of evolution.”
Some 14,000 visitors from across the United States and from as far away as Japan, England, and Germany visit the Platte each year. Many of them come in March for the three-day Rivers and Wildlife Celebration, which has been sponsored annually for 35 years by Audubon's Lillian Annette Rowe Bird Sanctuary, near Gibbon, Nebraska. Field trips, lectures, workshops, and close observation from blinds all emphasize the cranes' use of this small stretch of the river between Kearney and Grand Island—there's another section from North Platte to Sutherland—as a vital staging area for their migration to their nesting grounds in the far north. After leaving their winter quarters in Texas or New Mexico, sandhills may fly a thousand miles out of their way to rest and fatten up for several weeks before resuming their arduous flight to the tundra of Alaska, Canada, and northeastern Siberia. Why this age-old link between a bird whose population is stable or increasing and a river that is under siege?
Fossils from birds akin to sandhill cranes have been found in California and dated to 9 million or 10 million years ago. Taxonomists now distinguish five or six subspecies of sandhills, including endangered nonmigratory populations in Mississippi and Cuba, among the total subspecies population of 650,000 to 715,000 individuals. At present most of the migratory subspecies are doing well, including the lesser sandhill cranes, which account for 90 percent of the cranes migrating along the Platte. These lesser sandhills weigh a little more than six pounds, which is, on average, about four pounds less than their close cousins, the greater sandhill cranes.
“We like to think this part of the Platte is the largest singles bar in the world for cranes,” says Paul Tebbel, manager of the Rowe Sanctuary. “More pair bonds are formed here than at any other place in their annual life cycle.” Normally sandhill cranes are monogamous. But young cranes may make a few false starts along the Platte before sealing the relationship, while birds already mated strengthen the pair bond by repeatedly calling in unison. At times several cranes will break into spirited dances—leaping, lunging, bowing, and wing beating—prompted perhaps by the simple urge to relieve stress accumulated during the long migration. On rare occasions the dance touches off an unseemly brawl.
As cranes often arrive at their far-north breeding grounds before the local food supply becomes adequate, their success depends on the extra weight they pack on at staging areas along their migration routes. The Platte River remains a vital artery for millions of birds that migrate through or stay to mate in the valley. In spring vast flocks of geese, even a few migrant whooping cranes, appear. Endangered least terns and piping plovers come here to nest. Since long before humans arrived in the region, the Platte supplied the food, rest, and security these birds needed to sustain them during the hazardous flight or exhausting mating season that lay ahead. But the Platte is now an embattled river.
It has twin sources high in the snowy mountains of the Colorado Rockies. To the north of Steamboat Springs, dripping water forms a network of rivulets that rush down high peaks, mingle in streams winding north into Wyoming, and eventually come together to form the North Platte River. This branch flows southeast into Nebraska. South of Denver another mesh of streams coalesce in the South Platte, which turns northeast into Nebraska. There the two rivers meet to create the Platte's main stem and roll on for some 300 additional miles across the southern part of the state to join the Missouri River south of Omaha.
In presettlement Nebraska the Platte was a broad, shallow body of water (“a mile wide and an inch deep,” the settlers said, though in places the river was actually as much as three miles across). Geologists call it a braided river. Its course is broken and interlaced among numberless channels as the water searches for openings between the sandbars created by sand and silt it has carried on earlier trips from the Rockies and deposited in the riverbed. Here was nature's grand gesture toward the cranes. As the great flocks moved north, they encountered the river in a sea of prairie lands, bordered by wet meadows—land along the river flooded only seasonally, when both the Platte and groundwater levels rose. Each promised food in abundance: Prairie plants supplied seeds, and buffalo pies, which littered the drier grasslands, could be turned over and picked apart for grubs and other insects. The wetlands, meanwhile, harbored a cornucopia of worms, snails, frogs, and other small animals.
The Platte itself offered security. Eternally wary, the cranes typically advance to their roosting places in stages as dusk comes on. They stop short of the river, settling initially in the wet meadows. “We call this the parlor,” Tebbel says. “Just a handful may land at first. When the rest see that their colleagues aren't being eaten, they figure it's okay to come. Around sunset the first birds from the fields begin to land in the river. More and more birds come to the water as dusk arrives. It looks as if someone is chasing them. The whole process takes about an hour.”
There, in times past, the cranes found unobstructed views across the water and sandbars, a precaution against coyotes, foxes, and other predators catching them unawares. Frequent lightning-set fires removed dense vegetation along the shore. The river itself manipulated the landscape, as the rush of water from the late-spring snowmelt scoured sandbars of the high grasses, shrubs, and trees in which enemies might hide. By the time the vanguard of cranes arrived late the following February, water levels were again the proverbial “inch deep,” providing shallow resting places and open vistas for the massed thousands.
In 1905, in Wyoming, the federal government began building the Pathfinder Dam to hold water for irrigation on the North Platte's upper reaches. The project was a forerunner of the intricate system of dams, reservoirs, and canals that was soon under construction and continued steadily for much of the 20th century. Eventually 70 percent of the water in the Platte's upper reaches was diverted for irrigation, power, and flood control.
As flows to the river's Big Bend region diminished and the river channels shrank, the Platte's scouring force faded. Willows and cottonwoods took root, choking the channels and covering the sandbars. Today, in many places, the river is only one-tenth its presettlement width, and a hundred miles of the central Platte is no longer usable by the wary cranes.
Dean Plautz, who grew up along the Platte and raises corn, alfalfa, and soybeans on 80 acres within the Rowe Sanctuary, is dismayed by the changes he has witnessed since the 1970s. “My brothers and I played along the river in summer,” Plautz says. “If a duck hunter wanted to put up a blind on a sandbar, he'd have to bring out his own willows and stick them in the sand. Now it's all grown up in vegetation along here.”
Confronted in the early 1970s by a parched river that threatened disastrous consequences for cranes and other wildlife, environmentalists rushed to set things right. National Audubon bought the wet meadows and river channels that now make up the 1,248-acre Rowe Sanctuary. At the time water developers seemed to believe that no drop of the Platte should be left unappropriated. (A decade later the river was being shackled by upwards of 250 water-diversion projects.) Audubon led a coalition of environmental groups in fighting, often successfully, proposals for major dams and reservoirs.
Local animosity festered. When the postwar agricultural boom faltered, farmers, ranchers, and municipal leaders blamed “those outsiders.” But as Suzanne Winckler wrote in Audubon (“The Platte Pretzel,” May 1989), “While the OPEC oil cartel, Japanese grain importers, and policy makers at international meetings of GATT—the General Agreement on Tariffs and Trade—are among the mammoth forces that make or break American farmers, environmentalists are much more convenient scapegoats.”
Oblivious to the fuss, the cranes have so far found the adaptability and toughness to survive. They thrive in any climate, hot or cold, wet or dry, from Mexico to Alaska and Siberia. They'll stand for hours in blistering sun or icy rivers. They'll eat whatever looks edible—animal or vegetable. And so they have managed to adjust pretty well to changing food sources during more than a century of human development. Today they tear open cow pies rather than those of buffalo to feed on half-digested corn and newly hatched grubs. The corn left behind in fields by harvesting machines is also a major source of nutrition during the spring migration. “Cranes are beautiful birds, but they aren't ‘cute,' ” says Paul Tebbel. “They are lean, mean machines. They don't do well in captivity, and in fact they are hard to rescue when they get into trouble. Try to handle them and they will slash you with their claws.”
Still, their migration is fraught with danger. There are predators to escape and powerlines to avoid. Storms take a heavy toll. “It rained hard one spring night a few years ago,” Tebbel remembers. “Then the temperature dropped sharply, and in the morning the cranes were covered in ice. They were disoriented, slamming into walls and trees, and some were trampled by frightened cattle. In the morning we estimated anywhere from 3,000 to 10,000 dead cranes.”
The stakes continue to climb along the Platte, although the era of big dams is gone. Humans remain the biggest part of the equation. As people appropriate the dwindling water for agriculture, cities, and recreation, there have been attempts to develop more efficient farming techniques. Center-pivot irrigation is big in Nebraska. Originally this practice was designed to sprinkle water steadily on fields; it was then refined to deliver a fine spray. A further improvement, called drip-water irrigation, in which the nozzles dole out moisture thriftily, is available. But many farmers, saddled with hefty debt for lands and equipment, understandably feel that without added income, they are unable to upgrade their irrigation techniques. The farming community, however, seems ripe for the message that water resources are finite.
“If there's no water in the Platte for cranes, there's none for us either,” says Nebraska photographer and writer Michael Forsberg, who has documented the life cycle of sandhill cranes in his new book, On Ancient Wings (see “Art of the Wild,” Reviews, January-February). “The river's limited bounty has to be impressed on the public's consciousness. We must bring people to the table to talk about the issues and the concerns that are all around us. It will take tough leadership and great vision.”
Tebbel agrees that outreach to the community, rather than confrontation, offers the river's best hope. “Yes, habitat restoration is a part of the mix, too,” he says. “We do some clearing of the shoreline and sandbars to make the landscape inviting to cranes. But I think right now what Audubon does best are education, shaping public policy, building community relationships.”
Raising public consciousness about cranes requires changing public attitudes. The new Iain Nicolson Audubon Center on the Rowe Sanctuary is a magnet for local families, providing nature education for both adults and children (see “House of Straw, House of Hope"). Tebbel works with community leaders through the Kearney Visitors Bureau to assure that the river, cranes, and sanctuary increase income for local businesses. He estimates that 4,000 visitors during the crane migration contribute more than $1 million to the local economy.
“I've also made it my mission to expand ecotourism and an appreciation for Nebraska's wildlife in other areas of the state,” Tebbel says. “Crane watchers used to be thought of here as out-of-town folks who did stupid and inappropriate things. So I try to improve birding etiquette. We stress that both the farmers and the cranes belong here, while visitors ought to stay off private property and park their vehicles in safe places.”
Tebbel's effort to get farmers to understand the sanctuary's role in the community is paying dividends. More local people join in the crane watching. Farmers and their families look forward to the picnic he arranges for them at the sanctuary every year. Dean Plautz, who has come to look differently at the sanctuary's work, now serves on its stewardship board. “I've seen the drought here in recent years cut my corn harvest from 250 bushels an acre down to 30 bushels,” he says.
“Some local people still don't like environmental groups,” he continues, “but I think they are looking at things with their eyes wide shut. There are a lot more waterfowl around now—when I was a kid, if someone shot a goose, it seemed like it was news for the local paper. We can all work together to improve the river.”
Last summer the central Platte suffered through a 75-day stretch without rain. One afternoon Forsberg was walking west on the dry riverbed near the Rowe Sanctuary when he detected a peculiar glint in the sand ahead. “I saw a long tongue of water, less than a foot wide, a couple of inches deep, coming toward me,” he recalls. “The leading edge would seep into the sand and gravel, then bubble up. Right behind it there would be another surge forward. Seep in, bubble up. And there, in the trickle of water near the tip of this wisp of a stream, were little fish! It was as if the fish were pushing the stream onward. A small bird came out into the open to drink from it. Several geese circled overhead. At first, backlit by the sun, the scene seemed to be a mirage. But as I ran toward it, everything became plain. No matter how much we beat up on nature, there is still hope.”
© 2005 National Audubon Society