Mule Deer Case Study

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Coevolutionary divergence among sympatric species, such as elk and mule deer, created the idea of resource partitioning resulting from interspecific competition. Traditionally, resource partitioning was evaluated by species temporal avoidance, spatial separation and dietary differences (Stewart et al. 2010). Six different outputs influence mule deer behavior; density of roads, quality of forage, quantity of forage, quality of cover, quantity of cover and interactions between livestock, elk and mule deer (Edge et al. 1990). Habitat choice by mule deer can be a result of direct and indirect competition with elk and livestock, influencing their distribution and population (Edge et al, 1990, Long et al. 2008). Another form of competition is interference …show more content…

In midsummer, elk begin to use of forest with greater canopy cover on more easterly and northly aspects. This pattern is correlated with seasonal progression of forage abundance and quality (Ager et al. 2003). Effects of seasonality on elk and mule deer were prevalent in all seasons except spring. Summer through winter, forage availability often lead to dietary overlap creating spatial overlap, possibly resulting in exploitive competition (Stewart et al. 2002). Since mule deer are smaller bodied (mean body weight 35kg), absolute availability of food did not become an issue until selected biomass dipped below 50-100 kg/ha, while elk (mean body weight 160kg) were limited once selected biomass dipped below 1,500 kg/ha (Wickstrom et al. 1984). Wickstrom found that velocity of travel decreased in both species as selected biomass increased. It was determined that mule deer walked faster in understory habitats compared to grasslands, while elk moved at a similar rate for both habitat types. It is also believed that if an area is being heavily used by elk, deer will avoid or leave the area even if forage is abundant and their dietary overlap is low (Nelson …show more content…

Although cattle primarily influence the behavior of elk via strong dietary overlap (consuming mostly graminoids), they can affect mule deer behavior by reducing vegetative cover in essential fawning habitat and over grazing in essential foraging habitats (Stewart et al. 2002, Torstenson et al. 2006). Habitats that were previously grazed can have improved forage palatability, nutritional value, increased abundance and diversity of palatable perennial species, preferred my mule deer and elk, but if the habitat was grazed excessive and extant, these sites will be avoided (Taylor et al. 2004, Torstenson et al. 2006). When cattle grazing is presence, deer respond by decreasing the length of resting bouts and increasing the lengths of feeding bouts throughout the day. As cattle stocking rate increased, mule deer seemed to increase their home-range size including steep slopes, increasing their energetic costs (Kie et al. 1991).
It is important to understand the behavior of mule deer when coexisting with other ungulates such as elk and cattle where interspecies and interference competition is occurring. Studying competition through experimental approaches has been problematic due to the need for addition or removal of herbivores (Stewart et al. 2002). But understanding how behavioral avoidance between these species influences foraging habits, assumptions can be

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