In the 1930s, sandhill cranes were rare in Wisconsin. Despite the abundance of wetlands close to the Shack, the Leopold family rarely saw them, though occasionally they heard the cranes’ unmistakable, ethereal call. Sandhill populations have made a remarkable recovery, and now they can be seen through much of the United States.
A new day has begun on the crane marsh. A sense of time lies thick and heavy in such a place. ... The cranes stand, as it were, upon the sodden pages of their own history.
Aldo Leopold,“Marshland Elegy,” A Sand County Almanac
Sandhill Cranes and Wetlands
by Craig Maier
The sandhill crane takes its name from a particularly beautiful region in the broad sweep of grassland at the heart of North America. In central Nebraska, sand dunes created during the Ice Age have been stabilized by deep-rooted prairie plants including sand bluestem, evening primrose, leadplant, and hundreds of unique species of wildflowers and grasses. These Sand Hills ripple northward from the banks of the Platte River—characterized as “a mile wide and an inch deep” by settlers headed west on the Oregon trail—where shifting shallow channels, wetlands, and sandbars host the planet’s largest gathering of cranes each spring. Up to a half-million birds replenish their reserves as they pause here on their migration to wetlands further north in the Dakotas, Minnesota, and Canada.
Sandhill cranes taking off from a wetland in southern Arizona. Photo by Elaine Hyde.
Nearly 80 percent of the continent’s sandhill cranes gather along a 75-mile-long stretch of the Platte each spring, but the species actually includes several populations that follow separate migratory paths. Travel west across the continent in June, and you can find the omnivorous sandhill cranes digging for seeds and roots and hunting frogs and bugs among the Wisconsin farmscape, sheltering in an aspen copse as a summer solstice snowstorm casts a hush over the mountain headwaters of the Green River in Wyoming, and casting shadows as they glide over the sage brush flats and expansive wetlands of the basin and range country and volcanic plateaus of southeastern Oregon and northeastern California.
A smaller-bodied subspecies known as the lesser sandhill crane migrates to the high Arctic and even northeastern Siberia. Wintering grounds are found in central Florida, the Texas Gulf Coast, northern Mexico, and California’s Central Valley. Three subspecies live year-round in Mississippi, Florida, and Cuba.
Cranes may be confused with other large birds that utilize wetlands, most often the great blue heron—which is smaller, lacks the red forehead, and curls its neck against the body when it flies. Cranes fly with their necks and legs held straight out.
The other North American crane species, the whooping crane, is similar in size and build, but has stark white plumage on its body and a red head. The whooping crane is also extremely rare, with a just over 200 birds in one population that migrates from the Gulf Coast of Texas to Wood Buffalo National Park in Canada. A momentous effort is underway to re-introduce the whooping crane farther east, along a flyway between Wisconsin and Florida. The migration route is being established using ultralight aircraft to lead the cranes south. Free to return on their own, whoopers have used wetlands in downtown Chicago as a stopover!
Understanding Crane Migration
Map courtesy of the International Crane Foundation
~ Nina Leopold Bradley has been keeping three phenological entries on Sandhill cranes since 1974. She has found that they typically arrive in Wisconsin around March 5, she sees the first young crane close to May 7, and the last cranes head to their wintering grounds on about November 18 each year.
~ By November, the chicks born in May are ready to fly south on their own. Wisconsin’s cranes go to Florida for the winter, but Sandhill cranes in the western flyway winter in New Mexico and Arizona, and some travel as far as Mexico.
~ The biggest threat to Sandhills is loss of suitable wetland and riparian areas to use as stopovers during their migration. Eighty percent of all sandhills migrate through the Platte River in Nebraska, and development along the riverputs pressure on cranes.
Wetlands are vital to sandhill cranes—sedge meadows, marshes, and other wetlands are where the cranes build their nests and defend their eggs and young from predators. They are also important food sources across the full range of their migrations. The sandhill crane is not exceptional in its need for wetlands. It may be no surprise that areas with plentiful wetlands host a variety of creatures that have made themselves at home in the marshes, bogs, and fens, that cover much of the landscape, but many creatures of drier landscapes also depend on green oases in a dry land. As wetlands have been drained to make room for urban and agricultural expansion, the continued existence of their unique plant and animal communities is threatened, along with critical services—like soaking up flood waters, buffering coasts from storms, filtering water—that benefit people and land.
At the Leopold Shack today, cranes abound. Thousands fly over each summer evening to roost along the Wisconsin River. And, if you’re lucky, you might see the nesting pair with their young foraging for food in Leopold’s own marsh.
Want to know more?
Visit the International Crane Foundation for detailed information on Sandhills and other cranes. You can hear songs, view pictures, get identification tips, and discover many other details with this online guide created by the Cornell Lab of Ornithology.