Description: Includes the southern portions of California, Arizona, New Mexico and west Texas, extending into northern Mexico.

Climate: This region is arid to semi-arid, and has extreme temperatures, high evaporation rates, low rainfall that varies greatly from year to year, periodic droughts and poor soils. Precipitation ranges from 5 to 20 inches annually.

The deer: Deer are nonmigratory and greatly affected by droughts. Fawn recruitment is variable depending on amount and timing of rainfall. During dry years, fawn recruitment is typically below what is needed to maintain the population.

Limiting factors: Rainfall and competition with livestock. Winter rainfall affects the diversity, quality and quantity of next years' spring forbs, which directly affects the number of young deer that are born and survive to adulthood. Winter precipitation stimulates plant growth in the spring. Forbs are critical to the survival of deer in this ecoregion because browse plants don't contain adequate amounts of nutrients. Competition with other forb and grass-eating species such as livestock can have a great effect on mule deer, especially during years when rainfall is limited and range resources are scarce. Overgrazing in drought years can have long-lasting effects.

Recommendations:

1. Create sources of water in areas where water is limiting and where other potentially limiting factors are being addressed.

2. Monitor grazing so that livestock do not remove large amount of plants, particularly in years where drought or other climatic conditions stress deer.

3. Work with landowners to provide hunter access to public land.

4. Monitor human sprawl.