Factors influencing survival of desert mule deer in the greater San Andres Mountains, New Mexico

Abstract

Mule deer numbers have declined precipitously in the San Andres Mountains of southcentral New Mexico. To assess reasons for population declines, we monitored condition, survival, and causes of mortality for a range of 37 to 64 radio-collared, >1.5-year-old female mule deer annually, and a range of 14 to 31 radio-collared, >1.5-year-old male mule deer annually from 2003 to 2009, and modeled environmental factors affecting survival. We found annual survival rates of 0.74 to 0.86 for females and 0.74 to 0.92 for males, rates that were similar among years within sexes. Causes of mortality for 50 radio-collared females and 22 radio-collared males included predation (13 females, 2 males), accidents (4 females, 1 male), malnutrition (13 females, 7 males), disease (6 females, 2 males), unknown-not-predation (3 females, 6 males), unknown (11 females, 3 males), and harvest (0 females, 1 male). Condition of females varied among years and was poor in most years (i.e., lactating females had 1.0) > 0.937). Potential rates of increase of mule deer in the greater San Andres Mountains were limited by production and survival of fawns, rather than adult mortality.