500,000 Cranes Are Headed for Nebraska in One of Earth’s Greatest Migrations- page 4 | Science | Smithsonian
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(Melissa Groo)

500,000 Cranes Are Headed for Nebraska in One of Earth’s Greatest Migrations

At the end of March, 80 percent of the world’s cranes will converge upon one 80-mile stretch of land

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(Continued from page 3)

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Melissa and I drive into an area of nothing but cornfields. The gently rolling landscape is, as Melissa puts it, “lousy with cranes”—flocks of 50 to 200 or more variously known as creches, survival groups and extended families. These birds are skittish. The moment we pull up to one group, however slowly and quietly, they all take off. Sandhills are protected in Nebraska, but hunted in the majority of the U.S. and Mexican states and Canadian provinces they fly in. An estimated 33,000 a year are shot by hunters, who extol the cranes as “the rib-eye of the sky.” The birds seem to have a warning call that says, as one cranewatcher parses it, “Humans! Let’s get out of here!” Some of the groups just become agitated, and a few cranes start dancing. This is what Archibald calls “ambivalent behavior. They’re nervous, but not enough to fly, so they do something, anything.”

“I wish they knew they were safe,” Melissa moans. As in, Whew. I crossed the state line. No one can shoot us.

In the Nicolson Center at the Rowe Sanctuary, I had picked up the pocket-size Sandhill Crane Display Dictionary, by George Happ and Christy Yuncker-Happ, a must-have craniac resource on the basic moves of crane ballet. We tick them off as we see them performed by the birds that settle down and more or less accept our presence. Object-tossing, usually a corncob or a stick, is common. There’s the tall-investigative stance, when there is no threat but the bird is vigilant. Within a group of foraging cranes several usually assume it. They are the sentinels. If there is a visible threat, the bird goes into tall-alert, staring intently. Then intent-to-fly, leaning like pointers. We see 20 of them doing this, following a large bird that is moving through the rest of the pack.

Behind a scrim of cedar on a rocky point jutting into one field, serious dancing is going on. Dancing facilitates pair-bonding and ritually confirms decades-old bonds, allows rivals to assess each other and to ritually dissipate aggression. Pre-adult cranes practice dancing for three years before they mate. Parents educate their chicks by dancing with them. The bow is done after mating and as a threat when landing in a crowd of cranes. I wonder if the Japanese got their custom of bowing to each other from the cranes.

We don’t see the cloacal kiss, the actual deed, which takes only a few seconds, but we do see precopulatory behavior, a female facing away from the male and flattening her back and fanning out her wings to form a slanting ramp that he can mount, and the male approaching her in parade march. But they don’t do it. Maybe this is practice. Mating does happen on the Platte, and at the wintering grounds, Archibald says, though most of the courtship and copulation happen in the summer breeding grounds.

We see a confrontational crouch-threat, a ground-stab, which means look at me and let’s dance. And at afternoon’s end, 20 or 30 birds dance up a storm on a ridge against the sky.

I asked Archibald why the whooper has to be danced into egg production, and he said the presence of the mate you are paired to is very important. The two of you have to dance for a month or two, two, three times a day as reinforcement, before anything happens.

“The chemistry of attraction is as mysterious with cranes as it is with humans,” Brad Mellema told me. “Size doesn’t seem to matter. A pint-size male can yank a big female’s chain.” Leading scientists think the female has a gland on her back that emits seductive pheromones if she is receptive to a male’s advances.

Karine Gil-Weir, who was the Crane Trust’s population ecologist for five years, tells me from her home in Texas that she once saw a bonded pair of sandhills touching bills, kissing, which “has never been reported, and I never saw it again, but I saw a painting of two doing it at the Stuhr Museum in Grand Island,” she says. “The rituals are symbols of how to keep a family strong.”

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About Alex Shoumatoff
Alex Shoumatoff

Alex Shoumatoff is working on his eleventh book, about Borneo, and is launching a documentary series titled Suitcase on the Loose. Like his website, the series is dedicated to making people aware of and care about our rapidly disappearing natural and cultural diversity. He last wrote for Smithsonian in 1978, about the reintroduction of peregrine falcons.

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