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1. Energetics

2. Snow and Winter Severity

3. Digestive physiology

4. Plant Chemical Compounds and Digestion

5. Habitat and Diet

6. Sucession and Habitat Change

7. Livestock

8. Effects of Human Activities

9. Parasites

10. Population Dynamics

What is Competition?
  Competition between 2 species is a situation in which the 2 species use the same limited resource and 1 or both species suffer because of the interaction between them.  In addition, one or both species may have decreased survival or productivity leading to decreased population growth.

Potential Factors Affecting Competition:

Energetics
  Deer and elk usually select habitats and behave so that they conserve energy. They must continually make choices to maintain a positive energy balance.

Snow and Winter Severity  
   Winter weather can be very bad for mule deer.  Snow depth, cold temperatures and wind all contribute to reduced mule deer survival and productivity in following years. Elk can use areas with higher snow depths than deer.

Digestive Physiology
  Although deer and elk can and do eat the same types of food at times, there are physical differences that give elk an advantage over deer. Stomach size and body size require deer to eat higher quality foods to survive. In general, elk are able to eat prefered deer foods, but deer rarely eat common elk foods. Also, elk eat much more than deer, therefore it is more likely that foraging elk will impact deer more likely than deer will impact elk.

Plant Chemical Compounds and Digestion
  Many plants contain chemicals that affect digestion.  Because deer depend on more rapid digestion than elk, chemicals that slow digestion many be more likely to affect deer.

Habitat and Diet
  Deer tend to eat shrubs and forbs and elk eat more grasses and some forbs. Further, elk usually eat more plant species than deer and are less selective in which plant parts are eaten. Even with this natural separation, some conditions such as snow depth, can lead to greater diet similarity and competition for limited food.

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Potential Competitive Interactions Between Mule Deer and Elk in the Western United States and Canada: A Review. Lindzey, F.G., W.G. Hepworth, T.A. Mattson, and A.F. Reeves. 1997. Wyoming Cooperative Fisheries and Wildlife Research Unit, Laramie.