April 9, 2008
By Sue Benson,
Director of Education, CNHM
Six-million-year-old fossils unearthed in Nebraska make sandhill cranes the oldest living species of bird in the world, according to the International Crane Foundation (ICF). And it’s not hard to think of these animals as living fossils. With large bodies, long necks, stilt-like legs, and wingspans that can exceed six feet, the sandhill doesn’t have a lot of avian contemporaries on the Wisconsin landscape.
To many people, the distinctive, repeated k-r-r-r-oo call of early migrating sandhills ranks with the cry of the loon or the howl of a wolf as one of the fundamental resonances of nature. Wallace Grange, the early Wisconsin wildlife biologist whose personal land restoration effort later became the state’s Sandhill Wildlife Area, understood all this when he described a flock of sandhills as “a trace of colorful arrows gliding across time.”
These surprisingly graceful birds were once nearly relegated to fossil status in the state. Sixty-five years ago, it is believed that Wisconsin’s population had fallen to perhaps only 25 breeding pairs, centered in a few south-central counties. Their population had plummeted in response to excessive hunting and the loss of the wetland habitats upon which they depend for food and nesting sites.
Fortunately, with protection from hunting, greater protection and restoration of the state’s wetlands, and perhaps some behavioral changes by the birds themselves (adapting to breed in smaller wetlands and forage in agricultural fields), this tenuous population slowly began to expand. The expansion accelerated, and in the last 25 years a substantial rebound has taken place. In 2007, the Annual Midwest Sandhill Crane Count, sponsored by the ICF, tallied 13,764 cranes in Wisconsin and a total of 14,662 in Wisconsin and neighboring states.
The Sandhill Crane does not breed until it is two to seven years old. It can live up to the age of 20. Mated pairs of cranes participate in unison calling, a complex and extended series of coordinated calls. While calling, cranes stand in an upright posture, usually with their heads thrown back and beaks skyward during the display. Mated pairs stay together year round, and migrate as a group with their offspring. In some areas, wild sandhills preen iron-rich mud into their feathers, creating a rusty brown color which lasts throughout spring and summer. During fall these colored feathers molt and the birds return to their grayish appearance.
Although still an infrequent breeder in Wisconsin’s northern counties, local observations of sandhills are not the unlikely happenstance that they were just a decade ago. Sandhills are most active at dawn and dusk. Look and listen for them in wetlands, or nearby agricultural fields where they may forage for newly sprouting corn or worms and insects in the soil. Scan fields carefully with binoculars or look for movement; despite their size they blend in remarkably into a background of recently tilled soil, especially when the light is low. In flight, cranes fly with their necks extended and their legs trailing, in what has been called a “flying cross.”
Brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. They invite you to visit their facility in Cable on 43570 Kavanaugh Street or at the website at http://www.cablemuseum.org/ to learn more about their exhibits and programs.