Wednesday, January 25, 2012

Greater Sage-Grouse

Sage hen on the Yakima Training Center
Imagine.  An open grassy field surrounded by the sweet-smelling aroma of sagebrush in spring.  There is a strange sound in the silence, like a hooting whistle and a pop as the male greater sage-grouse puffs and struts to attract a female in his courtship dance.  The yellowish sacs on his neck fill with air as he postures, hoping for his lucky chance to attract the smaller, mottled brown hens.  His wings are splayed low to the ground and his tail is fanned out and straight up behind him in a fanciful display.  This is the famous courtship display of the Greater sage grouse that makes them unique.  They can live only in these sagebrush communities and display their courtship rituals in open areas surrounded by the large woody shrub.  It is essential for their existence.  It is food and shelter.  It is also a plant community at risk as a variety of anthropogenic disturbances are fragmenting and destroying it.  Without the sagebrush-steppe, the greater sage grouse will disappear.

The greater sage-grouse (Centrocercus urophasianus) are a large ground dwelling bird, in fact the largest of the grouse species, that were once prolific through regions where sagebrush (Artemisia tridentata) was the dominant vegetation.  They depend on these large woody sagebrushes during all parts of the year for survival.  Because of this, they are considered a sagebrush obligate species.  However, this is an ecosystem at risk due to many anthropogenic disturbances.  Much of the sagebrush has been removed, plowed under, and converted to agricultural lands suited for crops and livestock.  Expanding urban populations are also decimating and fragmenting the sagebrush habitat. Changes from frequent, low intensity fires to less frequent, but high intensity fires that remove all vegetation have also contributed to the loss of sage grouse habitat.  Overgrazing of livestock may also be a factor that has contributed to the decline of sage grouse in the last century.  

The greater sage grouse is largely dependent on sagebrush and accompanying herbaceous cover.  Unless action is taken to conserve and preserve this vast, injured ecosystem, the sage grouse will be extirpated from North America.  Recently, this unique species of grouse has become a species of concern for land management agencies such as the Bureau of Land Management, Fish and Wildlife, and Department of Natural Resources.

In March 2010, the United States Fish and Wildlife Service declared that federal listing of sage-grouse under the Endangered Species Act (ESA) is warranted, however there are other species facing a greater threat of extinction.  Therefore, sage-grouse are on the long list of potential candidates, waiting for their ESA bodyguard.  Despite this, management practices are being implemented nationwide to protect them and their declining habitat.  This is a critical step to prevent further population declines.  The focus of this thesis will study how local grazing regimes and coordinated management are being used to protect sage grouse habitat on the Wild Horse Wind Farm in Ellensburg, Washington.

Habitat: A Story Of Decline
As mentioned, sage grouse are a sagebrush obligate species.  They need this woody shrub most importantly to survive.  It is essential to their diet during all parts of the year, especially winter and early spring when grasses and forbs are unavailable (Connelly, Rinkes, and Braun 2011).  It is also used during nesting to conceal their eggs and young from predators.  Components of the sagebrush plant community are also very important to this ground-dwelling bird.  They use the grasses to stay hidden from those who might prey upon them.  The high protein forbs that grow under the sage and are intermixed with grasses are used to sustain them during brood-rearing.  Many anthropogenic disturbances have caused less and less of this habitat to be available to sage grouse.  It has been plowed under, burned, and removed.  It has been overgrazed.  It has been replaced with homes, towns, and roads.  Being known to have large home ranges, sage grouse need expanses of continuous shrub steppe habitat.  Therefore, not only is this species in trouble, so is the ecosystem.  By taking steps to ensure the survival of the greater sage grouse, sagebrush steppe habitats will be preserved for the grouse and the other wildlife that depend on it.  In this way, sage grouse are an umbrella species for the shrub-steppe ecosystem and other vertebrates that depend upon it (Rowland, Wisdom, Suring, Meinke 2006).

Historically, sage-grouse covered much of sage-brush land in Eastern Washington. Since the 1800's, their populations have declined due to loss of habitat, as mentioned, and also unrestricted hunting (Hays et al, 1998). As a result, they are now limited to two populations in what was once an extensive range (Figure 1). One is on the Yakima Training Center (YTC) and the other is on sections of private property in Douglas County where Conservation Reserve Programs (CRP) have allowed habitat to remain intact. The study area, located on the Wild Horse Wind Facility east of Ellensburg, Washington and between these two geographic locations, is at the western edge of the Colockum Wildlife Area. It is needed to provide connectivity between these two isolated populations of sage-grouse.  This study will help with these efforts to provide sage-grouse habitat between these two populations.

Figure 1

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