A flight of cranes rising from a bog at daybreak makes a strong case for the theory that birds descended from reptiles. Stilt-legged and snake-necked, cranes seem to have evolved very little since the first ones appeared over 40 million years ago in the Eocene Period. In Japan, where crane mythology abounds, the large wading birds symbolized longevity; they were once thought to live for a thousand years. Cranes in captivity have been known to live to the age of 60, but their look and bearing suggest an ancientness immeasurable in years.
The greater sandhill crane is often called the world's oldest species of bird. Nine-million-year-old fossil remains of Grus canadensis reveal the same gaunt figure and stiletto beak. Standing four feet in height, the sandhill is slate gray except for a blood-red patch of bare skin on its forehead. This reminded colonial Americans of the bog berry, which they subsequently named the crane-berry, or cranberry. In the spring, great flocks of sandhills migrate to nesting grounds in the sandy counties of Wisconsin as they have annually since the Ice Age. Bugling their deep, sonorous calls, the cranes slowly descend upon their ancestral marshes as if gliding down from the misty plateau of some lost world.
One April day last year, well before daylight, I stood in a marsh in central Wisconsin waiting to see sandhills or, perhaps, to hear them. The marsh was bordered by tag alder and dogwood and neatly split by a gravel road. Karen Voss, an ornithologist experienced in early morning vigils, had parked her van beside an iron bridge that the road crossed before entering a birch wood. Then Karen, her husband, Martin, and I stood in the middle of the road in the dark, drinking coffee from a thermos and taking some comfort in the notion that we weren't alone.
This was the morning of the ninth annual Wisconsin sandhill crane count, and we were among two thousand volunteers in designated marshes throughout the state. The count had begun in the mid-'70s as a high school science project and, sponsored for the past several years by the International Crane Foundation, has become a yearly rite of spring for Wisconsin's bird watchers.
The clangor of cranes traditionally ushers in the spring, signaling the farmer it's time to sow his seeds. But the temperature in our marsh this morning was 22°, and patches of snow still lay among the brown reeds. Karen worried that the cold weather had delayed the cranes' migration.
The Great Lakes population of greater sandhill cranes winters in the pine flats and prairies of Florida, feeding on sorghum and winter wheat, tubers and insects, and the occasional frog. (The Western population winters in Arizona, California, New Mexico and Mexico, while those of western Minnesota and Manitoba winter in Texas.) By late February and early March, the cranes begin their northward migration, spiraling up into the sky in corkscrew formations. The cranes then fly in V's or in lines as high as 13,000 feet. After a stopover at the Jasper-Pulaski Fish and Wildlife Area in northern Indiana, the cranes regroup and head for nesting grounds in the Great Lakes region. Our count had been scheduled to take place just after the cranes' arrival and just before the secretive business of incubating eggs. During this time, the sandhills would be at their most vociferous and visible, trumpeting and dancing as pairs choose and then defend nesting territories.
So far that morning, all I'd heard was the distant wash of trucks on the interstate a few miles to the east of our site. But the sky was starting to lighten. The road and woods took on shape in the silvery light. Sunrise is the cue. It is the reason the cock crows and, it seemed that morning, why the marsh suddenly overflowed with birdsong.
"I depend more on my ears than my eyes when I'm bird-watching," Karen said, and then proceeded to pick out of the cacophony the singers and their songs: snipe huhuhu-ing over here, woodcocks beezp-beezp-ingover there, a ruffed grouse drumming in the woods, red-winged blackbirds gurgling from swaying cattails and a single barred owl voicing a plaintive who...who...who cooks for you?
But no cranes trumpeting.
"I've spent so many mornings like this," Karen said, "standing in a marsh, dressed to the teeth, just waiting."