Forbs and Sage Grouse

The sagebrush steppe dominates the drier parts of the West, including parts of Southeast Oregon, much of Nevada, southern Idaho, western Wyoming, western Colorado, western Utah, and parts of New Mexico.

Sagebrush steppe covers 165 million acres of the West. Due to many factors, including farming, ranching, subdivisions, and, most importantly, range fires, sagebrush vegetation is disappearing from many parts of the West.

Sage grouse, one of the iconic birds of the sagebrush country.

One of the iconic birds of the sagebrush country is the aptly named sage grouse. As one might conclude, sage grouses rely on sagebrushes for a large proportion of their diet in autumn and winter. Sage grouse do not have a stony gizzard, so they can’t eat hard seeds, hence their reliance on sagebrush leaves.

The decline of sagebrush has led to a significant reduction in sagebrush-dependent species, including the pygmy rabbit, sage sparrow, and sage grouse. Other species, such as mule deer and pronghorn, which rely on sagebrush, are similarly affected.

Sagebrush species contain chemical compounds that make it difficult for most species to consume, but sage grouse have adapted to this abundant food source.

 One of the contributing factors in sagebrush decline is livestock grazing. Livestock impacts sagebrush habitat in several ways.

Livestock can trample biocrusts (lichens, mosses, and bacteria) that cover the soil surface between sagebrush plants. Loss of biocrusts promotes colonization of the site by cheatgrass, a highly flammable annual grass. As cheatgrass has come to dominate the sagebrush steppe, the acreage burnt by wildfire has increased dramatically.

Livestock grazing promotes cheatgrass which in turn enhances wildfire in sage brush.

Livestock also impacts sage grouse by consuming grasses that provide hiding cover for nests and birds.

Fences are oubiquitous on public lands to manage livestock movements, but harm many wildlife species including sage grouse. Photo George Wuerthner

Fences that crisscross much of the private and public lands to manage livestock are also a source of mortality for the grouse. Grouse frequently collide with the fences strewn across much of the sagebrush steppe and is a significant source of mortality in some areas.

Fences also offer perches for avian predators like ravens and hawks.

Livestock also damage riparian areas, such as green patches of vegetation along streams and wetlands. Sage grouse chicks, in particular, utilize this habitat early in their lives, feeding upon insects. Livestock trample streambanks and consume the riparian vegetation, depleting this critical habitat.

Forbs are wildflowers. Sage grouse depend on forbs for a critical part of their diet. Photo George Wuerthner

However, until recently, one of the least appreciated impacts of livestock grazing upon sage grouse was the consumption of forbs. Forbs are more commonly known as wildflowers. Sage grouse chicks eat forbs early in their life cycle.

Livestock grazing, mainly by domestic sheep which favor consumption of forbs, has depleted the seed bank of sagebrush steppe forb communities. Nevertheless, cattle also consume forbs when available.

One of the more recent discoveries is that not just any forb is suitable as sage grouse chick feed. While there may be an abundance of wildflowers among the sagebrush, they may not support sage grouse chicks if they are the wrong species.

Forbs like biscuit root and balsam root are consumed by sage grouse. Photo George Wuerthner

Sage grouse chicks consume the stamens and tender young leaves of some forbs. Forbs are high in protein and are easy to digest plants. Females also consume forbs to help in egg production. Forbs also attract insects that grouse consume.

Sage grouse will feed on the leaves of blazing star. Photo George Wuerthner

Among the most favored plants are yellow composites with milky sap like dandelion, crepis, legumes, tender legumes (milk vetch), and tender forbs like blazing star and globe mallow. Some lilies, like sego lily and camas lily, are used early in the season. Buckwheat is eaten early in the year, mostly the stamens.

The location of the forbs is essential. If chicks must travel far to get adequate forbs, they are more vulnerable to predators. Thus, livestock degradation of sage habitat can indirectly harm sage grouse.

All this suggests that Pie in the Sky comments that grazing can benefit sage grouse, ignore the cumulative impacts. Sure, one can reduce or mitigate one or two of the issues by fencing riparian areas or removing fences, but how can you prevent the trampling of biocrusts or cattle consumption of forbs?

Given the continued decline of sage grouse across the West, not to mention the role livestock grazing plays in the spread of cheatgrass and, thus, range wildfires, it’s time to retire grazing allotments on public lands. The best way to achieve this is through the Voluntary Grazing Permit Retirement program.