Male sage grouse display each spring to attract females. Photo: Robert Griffith by Matt Miller, senior science writer They appear like ghosts before light: small groups of plump birds standing amongst the sagebrush. They puff up, tail feathers erect, chest extended. Large air sacs are inflated on their breasts, making a distinct plop.

I'm on the spring display grounds of the greater sage grouse, one of the arid West's most iconic birds. Each spring males gather on these grounds, known as leks, to impress females with their display.

You have to get up early in the morning and sit motionless in the high desert. But you'll be rewarded in the soft light of dawn, as sage grouse begin their show. It's not unusual 15 males vying for the attention of female grouse on a lek, a site that grouse use year after year. (I've seen more than 50 on a lek at The Nature Conservancy's Crooked Creek Preserve).

It's one of the world's most memorable wildlife spectacles. But finding it has grown increasingly difficult, as sage grouse continue to decline across their range.

Why are sage grouse on the decline? And is there anything we can do about it?

Sage Grouse, Sagebrush and science example

The Not-So-Endless Sage

Sage grouse hen nests in native bunchgrass habitat. Photo: Ken Miracle

The story of sage grouse is the story of sagebrush, a shrub that at one point covered much of the arid western United States.

When European settlers traveled the Oregon Trail, the sagebrush deserts seemed endless and unforgiving. And indeed, sagebrush covered 150 million acres. Today, driving the interstate in the arid west, it still appears that this habitat stretches to the horizon.

A closer examination reveals much has changed.

Healthy sagebrush habitat is actually not just sagebrush but a rich mosaic of other shrubs, grasses and wildflowers. It is common to hear people to refer to sagebrush as "barren" or "empty," this is simply not the case. In fact, a wide variety of creatures rely on sagebrush to survive.

It's a very nutritious plant for mule deer and pronghorn. Many bird species survive only in sagebrush, including the aptly named sage sparrow and sage thrasher. There are even spiders found only in sagebrush.

And then there's the sage grouse. Nearly every phase of the grouse's life relies on sagebrush. They eat it, they nest in it, hide in it, seek cover during the winter under big sagebrush's branches.

Lose the sagebrush, and you lose the sage grouse.

It's that simple. For years, sagebrush was considered a nuisance plant, and range managers burned it, sprayed it and knocked it over by dragging chains across the desert.

Ecologists today estimate that only 10 percent of remaining sagebrush habitat is pristine. The threats come from a variety of perhaps-predictable sources: development, overgrazing, energy development, too-frequent fire, invasive weeds.

All this has caused a tremendous loss for sage grouse.

And as if that weren't enough, the grouse face another, unusual threat: native trees.