Condition, Survival, and Cause‐Specific Mortality of Adult Female Mule Deer in North‐Central New Mexico

Abstract

From December 2001 to December 2004 we monitored 30–44 adult female mule deer (Odocoileus hemionus) annually to assess the factors affecting survival and cause‐specific mortality. We found adult female survival of 0.63 (SE = 0.08), 0.90 (SE = 0.05), and 0.91 (SE = 0.04), 2002–2004, respectively. Starvation was the most common cause of mortality, accounting for 11/23 mortalities. Mean ingesta‐free body fat (IFBF) levels of adult females in December were low (6–9%), despite few (0–13%) lactating adult females, indicative of extremely nutritionally deficient summer—autumn ranges throughout the study site. A priori levels of IFBF and rump body condition scores (rBCS) were higher in deer that survived the following year regardless of cause of mortality. Logistical analysis indicated that models containing individual body fat, rBCS, mean population body fat, winter precipitation, precipitation during mid‐ to late gestation, and total annual precipitation were related (x2 ≥ 9.1; P ≤ 0.003) to deer survival, with individual IFBF (β =‐0.47 [SE = 0.21]; odds ratio = 0.63 [0.42‐0.94]) and population mean IFBF (β = ‐1.94 [SE = 0.68]; odds ratio = 0.14 [0.04‐0.54]) the best predictors; with either variable, probability of dying decreased as fat levels increased. Fawn production was low (2–29 fawns/100 ad F) and, combined with adult survival, resulted in estimated population rates of increase of ‐35%, ‐5%, and +6% for 2002–2004, respectively. Deer survival and population performance were limited in north‐central New Mexico, USA, due to poor condition of deer, likely a result of limited food resulting from both drought and long‐term changes in plant communities. Precipitation during mid‐ to late gestation was also important for adult female survival in north‐central New Mexico.

Fine‐scale genetic correlates to condition and migration in a wild cervid

“…Fat is an important determinant of fitness for mule deer (Bender et al. ; Johnstone‐Yellin et al. ; Tollefson et al.…”

“…Body fat also influences annual survival of adult females (Bender et al. ), pregnancy and twinning rates (Johnstone‐Yellin et al. ; Tollefson et al.…”

Functional analysis of Normalized Difference Vegetation Index curves reveals overwinter mule deer survival is driven by both spring and autumn phenology

“…Summer nutrition first affects adult female body condition [54], which predicts pregnancy rates [53–55], overwinter adult survival rates [54,56], litter size [57] as well as birth mass and early juvenile survival [57–59]. The addition of lactation during summer increases nutritional demand and thus is an important component of the annual nutritional cycle [47,60].…”

Factors Influencing Survival of Female Elk in a Harvested Population

“…Similarly, winter conditions may not have a large influence on survival rates for elk in the southern extent of their range in areas with relatively mild climates (Ballard et al 2000;Larkin et al 2003). In addition, density-dependent effects of disease or competition may have little impact on recovering or newly established populations (Bender et al 2007). Harvest, poaching, or other human-caused mortality sources may be the primary determinant of adult survival rates in areas where other factors, including predation, population density and winter conditions, have relatively little impact.…”