Chick-a-boom-boom at the lek
For the grouse, sex is very much a one-night stand, which explains why the males gather in late winter at traditional sites to perform their mating dances. Cocks provide no assistance to hens incubating eggs, or rearing broods. All they offer is their genes.
Lek is short for the Swedish term lekstalle, or mating place. Some leks may have been used for millennia. They tend to be in open places, such as old lakebeds, ridgetops, cropland, dirt roads or burned areas - with thick sage cover close by. Leks need to offer good views, so that females can check out the males, and males can keep an eye out for predators. Historical records indicate that hundreds of male sage grouse often gathered in the pre-dawn hours at a single lek, dancing for all they were worth.
The ritual of competition for females is largely limited to showing off, with very little fighting between males. By some accounts, the mating display of male sage grouse inspired some Native American dances.
First, each cock stakes out a few yards of territory upon which to perform his dance. He fans out the spiky feathers in his tail, lifts a halo of black feathers over his head and inflates two yellow air sacs on his chest, which protrude through the white breast feathers like egg yolks. Rearing up on his legs, the bird rapidly draws his wings across his ruff and makes several loud popping sounds - called booming - through the air sacs.
Sometimes the males charge each other, defending a piece of turf. The top males tend to claim the center of the lek; the skinny teenagers lurk around the outskirts, like underage kids outside the door of a bar.
Females cruise through this popping, puffing spectacle, sizing up their choices. They may visit several leks, but when a girl grouse makes up her mind, she evidently knows what she wants: some hens have been observed returning to a previously visited lek and going straight to the cock of her choice, where she offers herself for a quick copulation.
Female grouse tend to have similar taste in mates; 80 to 90 percent of the mating done at a lek is conducted by just one lucky male. The following winter, however, that male "almost always dies," according to biologist Jessica Young. Why this happens isn't clear.
Why all the pageantry? Lekking is a very efficient way for birds that live across a large landscape to size up their potential mates.
In sage grouse country, the males' booming can be heard for several miles when conditions are right. Some studies indicate that other noises, such as those produced by natural gas compressors and other machinery, may interfere with the breeding rituals, another sign of the birds' vulnerability.
If you're interested in observing the ritual dance on one of the leks, and helping the conservation effort, you can volunteer for the National Wildlife Federation's Adopt-A-Lek program. In April, volunteers go to field camps in Wyoming, Montana, Nevada and possibly eastern Washington and Northern California, to count grouse in leks, helping track populations. Contact Ben Deeble, NWF, 240 N. Higgins Ave., Suite 6, Missoula, MT 59802, or by e-mail, email@example.com, or by phone, 406/721-6705.