Great Gathering on the Great Plains
An esteemed ornithologist reflects on the annual transformation of Nebraska's Platte River into a crane mecca
Paul A. Johnsgard
EARLY SPRING along the Platte River is sheer magic. For more than a month migratory sandhill cranes pour into central Nebraska, attracted by the shallow river's abundant roosting sites and nearby meadows and farms for feeding. Looking like legions of gray ghosts from a distance, the birds often cover wet meadows and cornfields from one end to the other. Flocks of a thousand or more fly low over the river, their voices rising and falling as they approach, pass overhead and disappear. With nearly a half-million cranes stopping here each spring, the placid Platte is transformed into the site of the greatest gathering of these birds in the world.
Not only does the Platte shelter sandhill cranes at this time of year, it also is a magnet to nearly ten million ducks and geese that sprinkle the sky with intricate patterns from horizon to horizon for hours. Add to this the occasional appearance of an endangered whooping crane or a Eurasian "common" crane that has veered off course, and you have the ingredients of a spectacle that draws more than 20,000 people to the Platte Valley each spring. This coming together of the river, the birds and bird-watchers is a true congruence—a word derived from the Latin grus, which originally meant an assemblage of cranes.
Photo: © MICHAEL FORSBERG
WILD FOR WATER: Sandbars and wetlands in and around the Platte River provide staging grounds for migrating cranes to rest, feed and court potential mates (above). But these rites of spring have been disrupted in the past century, as people have built dams along the river and drained off much of its flow for agricultural and residential use. Conservationists are attempting to increase flows in the Platte for cranes and other wild visitors.
Cranes as a group have been present on Earth for more than 50 million years, and the 16 species of these large wading birds are scattered across most of the continents. I have studied them for the past 30 years, writing three books on the group, yet I never tire of seeing the birds in person. Each year I await the cranes' return to Nebraska with breathless excitement. Indeed, I mark the start of spring not so much by the calendar as by the day these birds first appear in the Platte Valley from their winter homes in Texas and New Mexico. Then there is a unique concatenation of cool breezes out of the south, of hundreds of clarion crane calls, of blue skies and of joy in witnessing the simple act of cranes dropping into the waiting safety of the river at sunset. There is also a majesty and balletlike beauty in the synchronized movements of hundreds of birds all simultaneously setting their wings, lowering their legs and parachuting downward, as if they knew they had finally returned home. There is the slow crescendo of their calling, as flock after flock drops into the river and as the sun sinks below the horizon, slowly transforming the silvery gray birds into black silhouettes.
What is it that brings so many cranes to the Platte Valley each spring? The answer is largely geography. The Great Plains offer an unobstructed flyway between the Gulf Coast winter habitat and the arctic breeding grounds for cranes and many other long-distance avian migrants. At a convenient mid-point in this long journey, the Platte courses east from the mountains of Colorado and Wyoming, moving slowly through farms and meadows to its eventual confluence with the Missouri River. The wide, shallow channels of the Platte provide roosting sites on bare islands and sandbars that are far away from coyotes and other land-based predators. The nocturnal protection offered by the river and the presence of spring food in the form of waste corn and invertebrates (which are abundant in the nearby wet meadows) are key attractions for cranes.
Each evening near sunset, flocks of a thousand or more cranes fly low over the river, their voices rising and falling as they approach, pass overhead and disappear again in the distance. As the sun sinks toward the horizon the birds become increasingly nervous, hoping to find a safe landing place before it is wholly dark. A lone, brave crane then touches down, followed moments later by another, then dozens and finally hundreds. Eventually as many as 20,000 may occupy a single roost, stretched out along a mile or more of the river. After some initial jostling for position, and rejoining of any pairs or family members separated in the confusion of landing, darkness settles on the crane roost. But even during the darkest hours it is never completely quiet, as nighttime conversations suggest that a few birds are always awake and on the alert for danger.
As darkness gives way to dawn, the volume of crane conversation gradually builds. Typically, small groups of Canada and white-fronted geese begin to leave their river roosts before the cranes, but with the first appearance of the sun the cranes start to stir. Then, sometimes as a single amorphous mass, an entire roost of several thousand birds may take flight, their combined notes shattering the dawn like the thunder of a sudden electrical storm. The flocks head out from the river toward their favorite foraging sites. Within half an hour after sunrise, the river is usually devoid of cranes, leaving it free for the common mergansers, mallards and pintails to feed and conduct their courtship rituals. The cranes spend most of the day in the cornfields and meadows harvesting whatever grain and invertebrates they can find, building up fat stores essential for their remaining spring migration and arctic breeding.
After five or six weeks of such regular cycles of daytime foraging and nightly roosting, the pattern breaks up, almost without warning. During a sun-warmed day in mid-April, when thermals are forming under cottony white clouds and a gentle breeze comes out of the south, the birds ascend in great slow-motion whirlwinds, their wings lifted by the invisible thermals until the cranes are almost out of sight. Their excited calls waft down as they head to nesting spots along the northern rim of the world. Soon after leaving the Platte Valley, the great flocks begin to split up, some heading for Hudson Bay shorelines and islands, others for the high-arctic tundras of far-northern Canada. Still others head to the Yukon-Kuskokwim delta of Alaska, and others to Siberian tundras some 3,000 miles away. They may not arrive at these nesting grounds until the end of May or early June, just as these areas are becoming snow-free.
Not all of the birds venture to the Arctic, however. Some of the larger sandhill cranes (the so-called "greater" race of the birds) nest in the northern Rocky Mountains, as far south as Wyoming. Others breed southward into the Great Lakes region. Greater sandhill cranes once even nested as far south as the marshlands of the Nebraska Sandhills in the north-central part of the state, where long breeding seasons and abundant food must have provided an ideal combination. But hunting pressure and disturbances caused by ranching and farming in the Sandhills eventually pushed nesting cranes out of Nebraska by the late nineteenth century. There is hope that the cranes will eventually reclaim the Sandhills marshes for nesting: A few of the birds have successfully nested south of the Platte in recent years, and some pairs have been sighted lately in the Sandhills.
It is risky business for sandhill cranes to nest near humans, as the birds are highly sensitive to disturbance. Once in Grand Teton National Park, I found a pair nesting at the edge of a small beaver pond, but I knew that if I set up a blind too near, the birds were likely to desert their nest. Luckily there was an old outhouse located about 50 yards away, dating from the time before the park had been established. I found that by sitting on one of the seats and opening the door just far enough to get my telephoto lens out, I had a perfect view. During the next few weeks, I felt I used that outhouse more than anyone else in its long history.
Although I have seen millions of sandhill cranes in my years of study on the Platte, I was in my sixties before I finally saw a wild whooping crane in Nebraska. It was on a March field trip with my university ornithology class. There was a mixture of rain and snow coming down, and I was driving with special care over a muddy road. Near Grand Island, one of the students innocently asked if I had seen the white bird standing among the flock of sandhills feeding in a nearby cornfield. I assumed it was probably a lone snow goose, since sometimes snow geese feed with flocks of cranes, but in spite of the bad road I thought we should stop and check it out. I could hardly believe my eyes when we located the whooper through a veil of snowflakes.
The whooping crane is the gold standard of American birds: It is the tallest, one of the rarest, and certainly one of the most beautiful of all North American bird species. Like the sandhills, whoopers migrate from winter habitat on the Gulf Coast to breeding grounds in the north. But unlike their smaller relatives, whooping cranes move in small flocks, with family-sized units the norm. They also are more water-dependent than sandhills, preferring foraging sites in wetlands rather than uplands, and seeking out roosting sites with wider stretches of river.
Historically, perhaps the entire species' population (possibly as many as 1,000 whooping cranes) moved up the central flyway each spring, many of them probably stopping at the Platte River. A survey I once made of whooping crane sightings recorded during the early to middle 1900s indicated that the "big bend" region of the Central Platte Valley was their most important stopover point. But as the Platte and its nearby wetlands declined from human use, the whoopers stopped coming here. Their total population eventually dropped to fewer than 50 birds. In recent decades as whooping crane numbers have slowly recovered, they have increasingly used the Rainwater Basin, an area of shallow wetlands south of the Platte, and some of the rivers and wet meadows in the Nebraska Sandhills, as far north as the Niobrara River.
Photo: © MICHAEL FORSBERG
ALLURING SPREAD: Dave Brandt (left), a biologist with the U.S. Geological Survey, sets up decoys on land near Phillips, Nebraska. Brandt and his colleagues are attempting to lure sandhill cranes so they can net them and attach transmitters to the birds. These devices will provide valuable data on the cranes' movements and habitat preferences. This study is a small part of a larger effort to safeguard crucial habitat for the birds.
The changes in whooping crane distribution in Nebraska probably are the result of wholesale "dewatering" of the Platte by agricultural and residential water users during the twentieth century. The river has lost as much as 70 percent of its historic flows to irrigation, eliminating many of its myriad channels, reducing its width, drying up the grassy meadows along its shorelines and allowing woody vegetation to grow on its margins and sandbars. Sandhill cranes have adjusted to these changes fairly well, but rarer avian species breeding on the river's sandy bars and islands—such as piping plovers and least terns—have not. Recent federal mandates for minimum river flows to protect these imperiled species have slowed changes to the Platte's ecology. Yet much of the damage done will be difficult to reverse. And the river's recovery was dealt a setback last year, when the driest, hottest summer in Nebraska history and a low snowpack in the Rockies caused the Central Platte to dry out completely for more than a month—the first time I have seen this in the four decades I have lived in the state.
Despite the challenges facing the Platte, the annual avian spectacle here remains enchanting. In all my years of studying birds around the world, from the Bering Sea to southern Chile to the Tasman Sea of Australia, nothing I've witnessed compares to the return of the cranes to Nebraska. From the middle or the end of February through the end of March, my excitement gradually builds along with the number of sandhill cranes. Then, during the ides of April, I sadly bid them farewell as flock after flock lifts off and heads resolutely northward. After they have gone, the Platte reverts to an ordinary Great Plains river, waiting silently for another congruence of the cranes.
Paul A. Johnsgard is Foundation Professor Emeritus at the University of Nebraska at Lincoln. This article is adapted from part of a forthcoming book, Great Wildlife of the Great Plains (University Press of Kansas).
Protecting Whoopers and Their Kin
Standing five feet tall and resplendent in its snowy white plumage, the whooping crane is the most statuesque and striking visitor to Nebraska's Platte River each spring. It is also the rarest, with fewer than 280 of the birds surviving in the wild.
Historically, small flocks of "whoopers" (named for their trumpeting call) stopped in central Nebraska on their way from Gulf Coast winter habitat to northern breeding grounds. At the Platte, they joined legions of sandhill cranes and other birds feeding in wetlands and fields during the day, and roosting on sandbars at night.
But in the past century, as much as 70 percent of the Platte's flow has been diverted for irrigation, flood control and residential use. These diversions have caused drastic changes to the river, causing crucial roosting sites and wetlands to disappear.
The National Wildlife Federation and its affiliate, the Nebraska Wildlife Federation, are working to reverse these worrisome trends and protect endangered whoopers. A key element in that effort is Whooper Watch, a volunteer research program funded in part through a grant from the National Fish and Wildlife Foundation. Each spring and fall, volunteers monitor sites along the Central Platte River for the presence of whooping cranes. They record information about crane sightings and habitat use. This information will be used to help develop and implement a recovery plan for crane habitat along the Platte.
"More than 60 volunteers have helped us watch for whoopers or carry out habitat conservation work that will benefit cranes," says Diane Beachly, Whooper Watch coordinator.
NWF and its Nebraska affiliate are also working with state and federal officials to develop a new water management program for the Platte River Basin. The goal: to protect land and manage Platte River dam operation and water use in ways that will conserve endangered species and their habitat.
"This may be our best chance to save one of America's great wildlife treasures," says Duane Hovorka, Nebraska Wildlife Federation executive director. "We can't afford to wait until the water's all gone to take action."
A draft Environmental Impact Statement on the water management program is due this fall, and the public will be invited to comment on the plan then.
For more information, see Platte River.