Odyssey of the Sandhill Cranes
Text and images copyright Michael Forsberg, all rights reserved

It is one of the wonders of the natural world: half a million sandhill cranes, more than 80 percent of the world’s population, descending on the Platte River Valley in central Nebraska every spring. It is the largest gathering of cranes anywhere, and they have been coming to this sliver of threatened habitat in North America’s Central Flyway for at least 10,000 years. On the Platte they rest and refuel for four to six weeks before flying to their breeding grounds in the upper Midwest, Canada, Alaska and Siberia.

In recent years, growing numbers of tourists from around the world also have migrated to the Platte to see and hear these grand birds crowd into river roosts at sunset and leave in massive, noisy flocks at first light. To many birdwatchers, spring migration is the sandhill crane’s defining moment. But it is only a small part of the story.

The sandhill crane (Grus canadensis) is thought to be the oldest surviving bird species in the world. A fossilized wing bone, found in 9-million-year-old, late Miocene deposits in Nebraska, is virtually identical in structure to the humerus of a modern crane.

Standing about four feet tall with six-foot wingspan, sandhill cranes inhabit open wetlands and shallow marshes. They are among the longest-lived birds, surviving 25 to 30 years in the wild. Scientists believe the species has survived because of its highly complex social behaviors, long-term care for its young, innate wariness and adaptability. Today, the sandhill crane is by far the most abundant of the world’s 15 crane species, including seven which are endangered.

The sandhill crane travels farther than any other crane species - for some individuals a roundtrip of 14,000 miles through four countries from eastern Russia to northern Mexico. Because they are so numerous, wide ranging and appealing, sandhills are the most easily identified of all the cranes. A growing number of crane watchers and local festivals celebrate the birds and their annual arrival at staging areas and wintering grounds.

According to the International Crane Foundation, the sandhill crane is the most thoroughly studied crane species and among the most studied of all North American wildlife species. Habitat restoration and conservation efforts beginning in the 1930s have brought one migratory subspecies, the greater sandhill crane, back to its vast breeding grounds in the upper Midwest. Today, most conservation work focuses on three non-migratory subspecies, the Florida, Mississippi and Cuban sandhill cranes, all either threatened or endangered by unregulated hunting in the past and, more recently, by development and habitat alteration in the South. The migratory sandhill subspecies are not considered threatened or endangered.

As some of its subspecies struggle for survival, the sandhill crane is contributing to efforts to save other crane species and other migratory birds. They have become surrogate parents in endangered crane breeding programs at the International Crane Foundation in Baraboo, Wisconsin, and contribute to research to establish new migratory corridors for whooping cranes. Outside the laboratory, the sandhill crane has become a “poster child” for public education and preservation of threatened wetland and grassland habitats, on which it and many less glamorous species depend.

Nowhere is this as evident as in Nebraska, where the sandhill crane has become a conservation symbol in the central Platte River valley. Nowhere are sandhill crane habitats more important, and 50 years of research has revealed the importance of the Platte to the well-being of the species.

The central Platte is critical to crane migration success. An often-used image depicts the region as the pinched waist of an hourglass. The top chamber covers a vast breeding range stretching from Hudson Bay to northeastern Siberia. The bottom chamber encompasses the wintering grounds extending from the Texas Gulf Coast westward through New Mexico and southward into Mexico. Every year, from late February through early April, the entire mid-continent population of sandhill cranes pours through the constricted passage between the chambers, an 80-mile-long, six-mile-wide swath of river, wetlands, forest and croplands from Grand Island to Lexington, Nebraska.

Three subspecies use the Platte: the greater sandhill crane (G.c. tabida), the Canadian sandhill crane (G.c. rowani) and the lesser sandhill crane (G.c. canadensis). The most obvious difference among the three is size. Greaters, the largest, weigh 10 pounds or more; lessers, the smallest, weigh about six pounds; Canadians average about eight pounds.

The lesser is the most populous, breeding throughout the arctic and subarctic regions of northern Canada, in coastal and interior Alaska and in northeastern Siberia. It winters primarily in the playa lakes region and riparian wetlands of eastern New Mexico, western Texas and northern Mexico.

Lesser sandhill cranes are the earliest and most numerous of the cranes using the Platte. Their largest concentrations are in the western part of the central Platte staging area. A few lessers also stage near North Platte and on the North Platte River near Ogallala.

The less studied Canadian sandhill crane is considered by some scientists to be an intergrade or transitional race. It breeds in the Canadian subarctic from Ontario to British Columbia, and winters primarily in coastal Texas. The greatest concentrations are in the central part of the Platte staging area. The greater sandhill crane breeds farther south than other migratory crane subspecies, primarily in scattered areas in Canada and from the Great Lakes states westward to the Pacific Ocean.

Five distinct geographical populations migrate along different flyways to scattered wintering grounds. The Prairie population, mostly birds from northwestern Minnesota, southwestern Ontario and southern Manitoba, passes through Nebraska and winters along the Texas Gulf Coast. It is most common in the eastern part of the Platte River staging area. Greaters often are the last to arrive on the Platte.

Recently the greater sandhill has begun to re-establish itself in parts of its former breeding range in western Iowa, Minnesota, the Dakotas and now, perhaps, Nebraska. Last summer, nesting cranes with young were observed on two Clay County wetlands south of the Platte River for the first confirmed nesting in Nebraska in more than 100 years. The birds are thought to have been greater sandhill cranes, the subspecies that nested in Nebraska until hunting and habitat destruction extirpated them by the 1930s.

Cranes come to the wide, shallow, braided channels of the Platte because it provides safe nighttime roosts, grain in crop fields and other nutrients in wet meadows along its margins. No other river system in the Central Flyway supplies their needs as fully.

Cranes prefer to roost on submerged sandbars in water about 18 inches deep in wide channels, some up to 500 yards, that provide protection from predators and people.

During the day, they spend much of their time in harvested cornfields feeding on spilled grain to build fat reserves. Grain makes up more than 90 percent of their diet. They also feed in wet meadows and low grasslands near the river. In those areas, which are fed by surface sloughs and connected to the river by groundwater, cranes forage for snails, earthworms, beetles and other invertebrates. The proteins and minerals they gain from those foods and from calcium nodules in the soil are necessary for egg and chick development.

The wet meadows and lowland grasslands also are important loafing areas; safe, secluded, sheltered spots where cranes rest, bathe and court. When storms prevent cranes from taking flight or when high water blocks their return to the river, they use wet meadows or tree-lined channels off the main branch of the Platte as alternate roosts.

Cranes gorge themselves while on the Platte, storing energy needed to complete migration and survive the early days on the northern breeding grounds. They can gain nearly a pound, about 10 percent of their body weight, during their stay. For nearly 10,000 years, the cranes returned to an undammed Platte, a braided, prairie river described by European explorers as “a mile wide and an inch deep”. The river valley was a vast complex of wetlands, shallow channels, sandbars, islands and prairie. Spring floods scoured the sandbars free of vegetation. Wet meadows and native prairie stretched across the valley.

Before Euro Americans settled on the Platte, the great crane migration is believed to have stretched 200 miles along the river. Their diet consisted primarily of roots, tubers and seeds that were abundant in the valley. Today, most cranes passing through Nebraska use only 80 river miles and fewer than 20 major roost sites, each holding 10,000 to 15,000 birds.

The long-term loss of Platte habitat is a critical threat to the species. Through the past hundred years, declining flows and the removal of sediment, which is now trapped behind dams and diversions, have altered the hydrology of the river, changed vegetation along the banks and reduced sandbar formation. The cranes are now crowded into fewer suitable stretches, increasing their risk of disease, the competition for food and vulnerability to spring storms.

The Platte, regulated by dams and pressured by politics, is narrower and deeper than it was a hundred years ago. Dams and diversions reduced flows by 70 percent, and in many places highways and suburban acreage developments crowd the river’s edge. Trees now cover banks, sandbars and islands that were open and unvegetated. Up to 75 percent of the wet meadows and native grasslands have been eliminated by agriculture, gravel mining and development. The best habitats are large wet meadows, low grasslands and wide river channels, all in close proximity. The few such places that remain are crowded with cranes.

To improve that situation, recent conservation efforts in the valley have focused on maintaining, improving and restoring habitat. Wooded islands and vegetated sandbars in the river have been cleared to increase roosting areas. Crop fields and overgrazed pastures have been replanted in native grass, and some have been landscaped to restore their natural drainage.

After 50 years of research, scientists agree there is still much left to learn about sandhill cranes. Although biologists speak in broad terms about the cranes’ migration, their needs, where they breed and how they behave at the nest, little is known about this secretive, ancient bird, whose history dates back perhaps as far as 60 million years.

What is certain is that during the past 40 years, the human population has increased from three billion to six billion and the number of endangered crane species has more than tripled. In few bird families are so many species endangered and, compared to the time that cranes have endured, it has happened in the blink of an eye. To researchers, sandhill cranes have become increasingly important - for their own sake and for the future of other species. They are a model for international conservation of migratory species and, like the bald eagle, wolf and grizzly, they are a symbol for habitat conservation.

For centuries, cranes have touched the lives of the humans in whose midst they have lived. With luck, the sandhill crane’s future will be as bright as its past.

Author's Note

Crane Continent - Sandhill Cranes in North America (a work in progress)
For a very long time, it has been a dream of mine to produce a picture book on the sandhill crane, a mystical and revered creature, the most ancient of bird species on the globe, and an ambassador for wetland habitats throughout much of North America.

Through generous private donor support, sponsorship from the International Crane Foundation, and help from a number of scientists, conservationists and friends, the book is slowly beginning to take shape and become a reality. The book will celebrate the species and the diverse wetland habitats in which it resides from as far north as Alaska to as far south as Cuba. The photographs will focus primarily on the sandhill crane's natural history and their habitats, but also will point towards the role the species plays in conservation, sometimes for it's own sake, sometimes for the sake of others.

The book's introduction will be written by a good friend, George Archibald, a world wildlife fund gold medal recipient, tireless conservationist, and the foremost crane biologist of his time. It will also feature several short "notes from the field" type essays, giving a glimpse into this several year photographic journey.

Ultimately, I hope that this book educates and inspires, relating in pictures and words the true value of these birds, and forwards the cause of crane and wetland conservation worldwide. Although a publisher has not yet been named, we plan to release in late 2004. Please stay tuned and check back from time to time as the work on the project progresses.

Michael Forsberg

Editor's Note

Nature photographer Michael Forsberg has spent the last decade photographing the wildlife and landscapes of the Great Plains. His work on sandhill cranes is recognized around the world. The Michael Forsberg Gallery is in Lincoln, Nebraska. To see more of Michael's work, please visit www.michaelforsberg.com.