Concerns over declining mule deer (Odocoileus hemionus) populations during the 1990s prompted research efforts to identify and understand key limiting factors of deer. Similar to past deer declines, a top priority of state wildlife agencies was to evaluate the relative importance of habitat and predation. We therefore evaluated the effect of enhanced nutrition of deer during winter and spring on fecundity and survival rates using a life table response experiment involving free‐ranging mule deer on the Uncompahgre Plateau in southwest Colorado, USA. The treatment represented an instantaneous increase in nutritional carrying capacity of a pinyon (Pinus edulis)—Utah juniper (Juniperus osteosperma) winter range and was intended to simulate optimum habitat quality. Prior studies on the Uncompahgre Plateau indicated predation and disease were the most common proximate causes of deer mortality. By manipulating nutrition and leaving natural predation unaltered, we determined whether habitat quality was ultimately a critical factor limiting the deer population. We measured annual survival and fecundity of adult females and survival of fawns, then estimated population rate of change as a function of enhanced nutrition. Pregnancy and fetal rates of adult females were high and did not vary in response to treatment. Fetal and neonatal survival rates increased in response to treatment, although the treatment effect on neonatal survival was marginal. Overwinter rates of fawn survival increased for treatment deer by 0.16–0.31 depending on year and fawn sex, and none of the 95% confidence intervals associated with the effects overlapped zero. Overwinter rates of fawn survival averaged 0.905 (SE = 0.026) for treatment deer and 0.684 (SE = 0.044) for control deer. Nutritional enhancement increased survival rates of fetuses to the yearling age class by 0.14–0.20 depending on year and fawn sex; 95% confidence intervals slightly overlapped zero. When averaging estimates across sexes and years, treatment caused fetal to yearling survival to increase by 0.177 (SE = 0.082, 95% CI: 0.016–0.337). Annual survival of adult females receiving treatment (Ś = 0.879, SE = 0.021) was higher than survival of control adult females (Ś = 0.833, SE = 0.025). Our estimate of the population rate of change (λ) was 1.165 (SE = 0.036) for treatment deer and 1.033 (SE = 0.038) for control deer. Increased production and survival of young (i.e., fetal, neonatal, and overwinter fawn survival) accounted for 64% of the overall increase in λ, whereas adult female survival accounted for 36% of the increase in λ. The effect of nutrition treatment on overwinter fawn survival alone accounted for 33% of the overall increase in λ. We documented food limitation in the Uncompahgre deer population because survival of fawns and adult females increased considerably in response to enhanced nutrition. We found strong evidence that enhanced nutrition of deer reduced coyote (Canis latrans) and mountain lion (Puma concolor) predation rates of ≥6‐month‐old fawns and adult...

Summary1. Well-informed management of harvested species requires understanding how changing ecological conditions affect demography and population dynamics, information that is lacking for many species. We have limited understanding of the relative influence of carnivores, harvest, weather and forage availability on elk Cervus elaphus demography, despite the ecological and economic importance of this species. We assessed adult female survival, a key vital rate for population dynamics, from 2746 radio-collared elk in 45 populations across western North America that experience wide variation in carnivore assemblage, harvest, weather and habitat conditions. 2. Proportional hazard analysis revealed that 'baseline' (i.e. not related to human factors) mortality was higher with very high winter precipitation, particularly in populations sympatric with wolves Canis lupus. Mortality may increase via nutritional stress and heightened vulnerability to predation in snowy winters. Baseline mortality was unrelated to puma Puma concolor presence, forest cover or summer forage productivity. 3. Cause-specific mortality analyses showed that wolves and all carnivore species combined had additive effects on baseline elk mortality, but only reduced survival by <2%. When human factors were included, 'total' adult mortality was solely related to harvest; the influence of native carnivores was compensatory. Annual total mortality rates were lowest in populations sympatric with both pumas and wolves because managers reduced female harvest in areas with abundant or diverse carnivores. ‡Present address: Natural Resources Canada, 506 Burnside Road W, Victoria, BC V8Z 1M5, Canada *Correspondence author. E-mail: jedediah.brodie@gmail.com †Authorship alphabetical after B. Johnson.© 2013 This article is a US Government work and is in the public domain in the USA. 2013, 50, 295-305 doi: 10.1111/1365-2664.12044 4. Mortality from native carnivores peaked in late winter and early spring, while harvest-induced mortality peaked in autumn. The strong peak in harvest-induced mortality during the autumn hunting season decreased as the number of native carnivore species increased. 5. Synthesis and applications. Elevated baseline adult female elk mortality from wolves in years with high winter precipitation could affect elk abundance as winters across the western US become drier and wolves recolonize portions of the region. In the absence of human harvest, wolves had additive, although limited, effects on mortality. However, human harvest, and its apparent use by managers to offset predation, primarily controls overall variation in adult female mortality. Altering harvest quotas is thus a strong tool for offsetting impacts of carnivore recolonization and shifting weather patterns on elk across western North America. Journal of Applied Ecology

: The assumption of independent sample units is potentially violated in survival analyses where siblings comprise a high proportion of the sample. Violation of the independence assumption causes sample data to be overdispersed relative to a binomial model, which leads to underestimates of sampling variances. A variance inflation factor, c, is therefore required to obtain appropriate estimates of variances. We evaluated overdispersion in fetal and neonatal mule deer (Odocoileus hemionus) datasets where more than half of the sample units were comprised of siblings. We developed a likelihood function for estimating fetal survival when the fates of some fetuses are unknown, and we used several variations of the binomial model to estimate neonatal survival. We compared theoretical variance estimates obtained from these analyses with empirical variance estimates obtained from data‐bootstrap analyses to estimate the overdispersion parameter, c. Our estimates of c for fetal survival ranged from 0.678 to 1.118, which indicate little to no evidence of overdispersion. For neonatal survival, 3 different models indicated that ĉ ranged from 1.1 to 1.4 and averaged 1.24–1.26, providing evidence of limited overdispersion (i.e., limited sibling dependence). Our results indicate that fates of sibling mule deer fetuses and neonates may often be independent even though they have the same dam. Predation tends to act independently on sibling neonates because of dam‐neonate behavioral adaptations. The effect of maternal characteristics on sibling fate dependence is less straightforward and may vary by circumstance. We recommend that future neonatal survival studies incorporate additional sampling intensity to accommodate modest overdispersion (i.e., ĉ = 1.25), which would facilitate a corresponding ĉ adjustment in a model selection analysis using quasi‐likelihood without a reduction in power. Our computational approach could be used to evaluate sample unit dependence in other studies where fates of individually marked siblings are monitored.

Estimating survival of the offspring of marked female ungulates has proven difficult in free-ranging populations yet could improve our understanding of factors that limit populations. We evaluated the feasibility and efficiency of capturing large samples (i.e., .80/yr) of neonate mule deer (Odocoileus hemionus) exclusively from free-ranging, marked adult females using vaginal implant transmitters (VITs, n ¼ 154) and repeated locations of radiocollared females without VITs. We also evaluated the effectiveness of VITs, when used in conjunction with in utero fetal counts, for obtaining direct estimates of fetal survival. During 2003 and 2004, after we placed VIT batteries on a 12-hour duty cycle to lower electronic failure rates, the proportion that shed 3 days prepartum or during parturition was 0.623 (SE ¼ 0.0456), and the proportion of VITs shed only during parturition was 0.447 (SE ¼ 0.0468). Our neonate capture success rate was 0.880 (SE ¼ 0.0359) from females with VITs shed 3 days prepartum or during parturition and 0.307 (SE ¼ 0.0235) from radiocollared females without VITs or whose implant failed to function properly. Using a combination of techniques, we captured 275 neonates and found 21 stillborns during 2002À2004. We accounted for all fetuses at birth (i.e., live or stillborn) from 78 of the 147 females (0.531, SE ¼ 0.0413) having winter fetal counts, and this rate was heavily dependent on VIT retention success. Deer that shed VITs prepartum were larger than deer that retained VITs to parturition, indicating a need to develop variable-sized VITs that may be fitted individually to deer in the field. We demonstrated that direct estimates of fetal and neonatal survival may be obtained from previously marked female mule deer in free-ranging populations, thus expanding opportunities for conducting field experiments. Survival estimates using VITs lacked bias that is typically associated with other neonate capture techniques. However, current vaginal implant failure rates and overall expense limit broad applicability of the technique. (JOURNAL OF WILDLIFE MANAGEMENT 71(3): 945-954; 2007)

Modified fencing structures have been recommended with the intention of enhancing ungulate movement. Ungulates such as mule deer (Odocoileus hemionus) and white‐tailed deer (O. virginianus) typically negotiate fences by jumping over them. We examined 2 fine‐scale fence crossing decisions to determine factors influencing 1) crossing success and 2) the mode of crossing by 2 sympatric deer species. From 2010 to 2016, we used remote cameras along fence lines in 2 study areas—Canadian Forces Base Suffield in southeastern Alberta, Canada, and The Nature Conservancy's Matador Ranch in north‐central Montana, USA—that captured images of deer–fence interactions before and after fence modifications were installed. We used logistic regression to model the probability of deer successfully crossing a fence and mode of crossing (jumping over vs. crawling under) based on fence characteristics and demographic factors. We documented 486 crossing attempts, of which 313 were successful (64.4%), indicating that pasture fences acted as a semipermeable barrier to deer. Of these 313 successful attempts, 152 crawled under the fence (48.6%) as opposed to jumping over it. We documented behavioral differences in mode of crossing between species when successfully crossing a fence. Results indicate that deer are selecting known crossing sites at broad scales as places to negotiate fences, and when assessing finer scale decisions at these sites, white‐tailed deer seemed to acclimate better than mule deer to our imposed changes (switched from crawling under to jumping over the fence). Though sample size was low in terms of use at modified fence sites, we recommend visually inconspicuous modifications (such as clips to increase the bottom wire height as opposed to goat‐bars) when implementing pasture fencing that was friendlier for deer. We also recommend modifications be implemented strategically; placement of modifications may be just as important to consider as the modification type. © 2018 The Wildlife Society.