Sharp-tailed Grouse - Habitat Fragmentation

Habitat Fragmentation

Habitat fragmentation has been one of the driving factors of sharp-tailed grouse decline across its entire range for all subspecies throughout North America (Silvy and Hagen 2004). The type of habitat fragmentation varies from ecological succession, as shrub/grassland areas transition into forested areas. Also fire suppression, tree plantings, limiting logging practices, and an increase of invasive woody species have also led to sharp-tailed grouse habitat fragmentation. The largest contributor to habitat fragmentation of sharp-tailed grouse has been the agriculture industry. The Homestead Act of 1862 opened up great expanses of virgin prairie in the west to early settlers. By 1905 about 41 million hectares of the west had been homesteaded (Olsen 1997). Much of this land was in semi-arid rangelands with sub-marginal precipitation to support crop production (Olsen 1997). Once this land was plowed, a change in the land characteristic occurred forever. Another aspect of agriculture that affects habitat fragmentation for grouse is unmonitored and excessive cattle grazing (Kirsch et al. 1973; Giesen and Connelly 1993; Kirby and Grosz 1995; Reece et al. 2001; Sidle 2005). Cattle can be an important tool to manage habitat structure for sharp-tailed grouse when managed properly (Evens 1968; Kirby and Grosz 1995; Sidle 2005). Habitat of sharp-tailed grouse was severely affected by early settlers before cattle grazers understood the impact to the environment from over grazing. A secondary affect that early agriculture had during the years of the Dust Bowl and Great Depression in the late 1920s and early 1930s was when homesteaders abandoned the unproductive land (Olsen 1997). The United States government bought up much of this land through the Land Utilization Program, with management eventually controlled by the United States Forest service and the Bureau of Land Management (Wooten 1965; Olsen 1997). During the drought years of the 1930s, these agencies re-vegetated some of these areas with non-native highly competitive vegetation such as smooth brome (Bromus inermis) and crested wheatgrass (Agropyron cristatum) (USDA- US Forest service 2001). These plants served their purpose by re-vegetating and protecting the soil. But, these invaders became great competitors and directly affected native vegetation. In some instances crested wheatgrass and smooth brome have forced out native vegetation, creating monoculture habitats. Monoculture habitats are not favored by sharp-tailed grouse, as they prefer sites with high heterogeneity. Hamerstrom (1939) was quoted as saying "More important than the individual cover plants is the fact that most of the nests of all species were in cover mixtures rather than pure stands."