| The goal of my research was to identify the effects of water developments on mule deer (Odocoileus hemionus) inhabiting a Mojave Desert ecosystem. I focused my research efforts on those ungulates because many water development projects are implemented to induce changes in their spatial patterns and population performance (Broyles 1995, Krausman and Etchberger 1995, Dolan 2006, Cain et al. 2008). The results of my research could have profound implications for wildlife management in desert ecosystems, as well as for water management in the west.;Mule deer are widely distributed throughout western North America and occupy a variety of habitat types, including the Canadian boreal forest, the Great Basin Desert, the Colorado Plateau, and the Mojave Desert (Wallmo 1981). The ability to adapt to extreme temperatures and precipitation gradients distinguishes mule deer from many other species of ungulate (Wallmo 1981). In areas of low habitat productivity, such as desert ecosystems, mule deer require large areas to maintain viability of populations (Marshal et al. 2006b). Nutritional quality and availability of forage (Rautenstrauch and Krausman 1989, Marshal et al. 2005), cover (Ordway and Krausman 1986), natal sites (Fox and Krausman 1994), and availability of free-standing water (Marshal et al. 2006a) are all used to assess suitability of those large areas for long-term persistence of mule deer. During times of water scarcity, mule deer are particularly reliant on the availability of free-standing water (Rautenstrauch and Krausman 1989, Rosenstock et al. 1999). In arid regions and particularly during the hot-dry season, the availability of permanent sources of water may be the most important component of habitat for mule deer.;Spatial distributions of mule deer are intimately linked to availability of resources on the landscape. Seasonal changes in space use due to changes in resource availability have been documented in a variety of ungulate species including desert sheep (Cain et al. 2008) and desert mule deer (O.h. crooki; Relyea et al. 2000). During times of water scarcity, typically the hot-dry season, water content of forage is also limited. Mule deer have been reported to change distribution and home range to incorporate permanent sources of water during the hot-dry season (Rautenstrauch and Krausman 1989).;Conversely, when permanent water sources are unavailable, mule deer have been shown to increase daily movements and home range size to locate sources of water (Hervert and Krausman 1986), which is likely an expensive energetic allocation. Mule deer inhabiting resource-limited environments exhibit larger home ranges and increased movements to meet their energetic demands and, alternatively, they exhibit smaller home ranges and decreased movements in environments with abundant resources (Ordway and Krausman 1986, Relyea et al. 2000, Marshal et al. 2006a, Bender et al. 2007). If water is a limiting resource in desert landscapes inhabited by mule deer, then patterns of space use would be influenced by changes in the availability of that resource.;Changes in density and distribution of ungulate populations are often linked to changes to changes in body condition, productivity, and survival (McCullough 1979, Eberhardt 2002, Cook et al. 2007, Bishop et al. 2009). Moreover, populations constrained by density-dependent processes exhibit poor body condition, low productivity, and low survival when at or near ecological carrying capacity (McCullough 1979, Kie et al. 1980, Stewart et al. 2005). The underlying mechanisms of population dynamics dictating density dependence are driven primarily by the availability and quality of resources on the landscape (Kie and White 1985, Stewart et al. 2002, Bender et al. 2007, Bishop et al. 2009, Parker et al. 2009). Mule deer inhabiting desert ecosystems occur at low densities with large ranges (Marshal et al. 2006b) presumably due to limited availability of resources on the landscape (Marshal et al. 2005, Bender et al. 2007, Bleich et al. 2010). If availability of permanent sources of water is limiting in desert environments, then mule deer should reduce their effort spent acquiring free-water when sources of permanent water are provided. Mule deer could then reallocate those efforts to foraging, which could, ultimately, improve body condition, productivity, and survival.;In chapter 1, I evaluated movements, distribution, and resource selection (i.e., patterns of space use) of mule deer in response to provisioning of water developments in Mojave National Preserve, California, USA from 2008-2011. In chapter 2, I evaluated responses in body condition and traits of demography of mule deer to provisioning of water developments. (Abstract shortened by UMI.)... |
