Birds
Greater Sage-grouse
Centrocercus urophasianus · also called greater sage-grouse, sage grouse, sage hen
Before dawn each spring, the sagebrush plains of the American West fill with a sound like water dripping into a giant vat — dozens of male greater sage-grouse on a traditional dancing ground, fanning spiky tails and popping the two yellow balloons on their chests. The whole species lives and dies with the sagebrush.
Overview
Greater sage-grouse are the largest grouse in North America, living in the sagebrush steppe of 11 western US states and two Canadian provinces. Adults eat sagebrush leaves for much of the year and nothing else in winter; chicks need insects at first. Males are 65–75 cm and about twice the weight of females.
The lek
Males return to the same open display grounds year after year before dawn in spring. Each defends a small patch, struts with tail fanned and chest ruff puffed, and inflates two bare yellow air sacs, snapping them against stiff feathers to make a swishing double-pop heard up to 3 km away. A few dominant males on the best central spots father most of the chicks; the female then nests and raises the brood alone.
A sagebrush obligate
The bird cannot live without large, intact sagebrush — for food, nesting, and cover. Its populations have fallen an estimated 80%+ since 1965 as sagebrush is lost to farming, energy development, wildfire, and invasive cheatgrass.
Status
The greater sage-grouse is Near Threatened and declining, with perhaps 200,000–500,000 birds left. It is treated as an umbrella species — protecting its habitat shelters hundreds of other sagebrush animals — and sits at the centre of Western land-use conflict.
Greater Sage-grouse: common questions
What happens at a sage-grouse lek?
A lek is a traditional communal display ground, an open patch of low or sparse vegetation that the same population of males uses generation after generation. In early spring, males fly in before first light and spread out across the lek, each defending a small patch. As dawn breaks they begin to strut — a male puffs out his white chest ruff, fans his stiff pointed tail feathers into a spiky halo, takes a few steps, and then inflates the two yellow air sacs on his breast and rapidly deflates them against his feathers to produce the strange swishing "pop-pop" sound, repeating the whole sequence over and over. Females walk among the displaying males, assess them, and almost all choose to mate with one or two dominant males holding the prime central spots. After mating the female leaves to nest and raise the brood entirely alone; the males play no further part.
Why does the greater sage-grouse depend so completely on sagebrush?
The bird has evolved to live off a plant most animals avoid. Sagebrush leaves are bitter, aromatic, and loaded with terpenes and other chemicals that deter herbivores, but sage-grouse have a digestive system able to process them, and for the whole winter, when snow covers everything else, sagebrush leaves are essentially their only food. Sage-grouse also nest under sagebrush canopy, shelter their chicks in it, and roost in it. Because the bird cannot substitute another habitat, it is what ecologists call a sagebrush obligate, and its fate is tied directly to the fate of the sagebrush sea. Where large, connected, healthy stands of sagebrush remain, sage-grouse persist; where sagebrush is plowed, burned, fragmented, or replaced by invasive cheatgrass, they disappear.
Is the greater sage-grouse endangered?
It is listed by the IUCN as Near Threatened and has declined severely — surveys of males at leks suggest the population has fallen by around 80 percent since 1965 and is still trending down, with tens of millions of birds historically reduced to a few hundred thousand. In the United States it has repeatedly been considered for listing under the Endangered Species Act; a 2015 decision not to list it was paired with a large multi-state federal and private conservation plan, because listing would have brought sweeping restrictions on ranching, farming, and oil and gas activity across the West. The bird has become a symbol of the tension between species conservation and land use, and its sagebrush habitat shelters hundreds of other declining species, so it is treated as an umbrella species.
What eats sage-grouse, and what are the main threats?
Natural predators include golden eagles, hawks, coyotes, badgers, and foxes, and ravens and ground squirrels take many eggs; predation is a normal pressure that healthy populations absorb. The serious threats are to habitat and are almost all human-linked — conversion of sagebrush to cropland and pasture, oil, gas, and wind energy development and the roads, fences, and power lines that come with it (power lines give raptors and ravens perches over otherwise open country), larger and more frequent wildfires, the spread of invasive cheatgrass that carries those fires and replaces sagebrush, encroachment of pinyon and juniper trees, drought, and disturbance at leks. Sage-grouse also die in collisions with fences and vehicles and are affected by West Nile virus.