Mule deer (Odocoileus hemionus) are an iconic species of wildlife, and populations of mule deer across much of the western U.S. have experienced recent fluctuations in size. Factors that affect the survival and subsequent recruitment of juveniles may be the preeminent cause of population fluctuations for mule deer in many areas. Many factors, including habitat loss, extreme weather, intense predation, timing and synchrony of parturition, and competition with other species may be influencing these changes. We studied two potential factors that can influence the survival of neonate mule deer in southern Utah. To better understand how predation affects mule deer, we first implemented a study of the response of mule deer to removal of coyotes in southern Utah. We monitored survival and cause-specific mortality of neonate mule deer in areas where coyotes were removed and where they were not removed. We used multi-model inference within Program MARK and a known-fate model to estimate survival of neonate mule deer in both treatments (removal and non-removal), and to investigate factors potentially influencing survival. Our results indicated that coyote control can decrease mortality and increase survival of neonate mule deer in some situations. Removal of coyotes was most effective when removal efforts occurred for multiple consecutive years, and when control efforts occurred in or near fawning habitat. Second, we examined how synchrony of parturition affects the survival and cause-specific mortality of neonate mule deer. Reproductive synchrony is a strategy that influences the survival of juveniles and the growth of populations. Our objective was to test three possible explanations for the synchrony of parturition in mule deer; 1) pressure of predation on newborns, 2) a hybrid of predation and environmental effects, and 3) weather and food availability. To determine the effects of the timing of parturition on the survival and predator-related mortality of neonate mule deer, we used multi-model inference within Program MARK and a known-fate model. Our results indicated that the timing of parturition influenced survival and predator-related mortality of neonate mule deer. There was a lag between the onset of parturition of mule deer and predation of mule deer by fawns; individuals born close to the onset of parturition had higher survival and lower predator-related mortality than those whose births were delayed relative to the onset of parturition. Since predators selected for neonate mule deer that were born late, predator learning may partially explain reproductive synchrony in mule deer. Environmental factors may have a greater effect than predation on the survival of early-born individuals.

Changes in the abundance and distribution of free (drinking) water can influence wildlife in arid regions. In the western USA, free water is considered by wildlife managers to be important for bighorn sheep (Ovis canadensis), elk (Cervus elaphus), mule deer (Odocoileus hemionus), and pronghorn (Antilocapra americana). Nonetheless, we lack information on the influence of habitat and landscape features surrounding water sources, including wildlife water developments, and how these features may influence use of water by sexes differently. Consequently, a better understanding of differential use of water by the sexes could influence the conservation and management of those ungulates and water resources in their habitats. We deployed remote cameras at water sources to document water source use. For mule deer specifically, we monitored all known water sources on one mountain range in western Utah, during summer from 2007 to 2011 to document frequency and timing of water use, number of water sources used by males and females, and to estimate population size from individually identified mule deer. Male and female mule deer used different water sources but visited that resource at similar frequencies. On average, mule deer used 1.4 water sources and changed water sources once per summer. Additionally, most wildlife water developments were used by both sexes. We also randomly sampled 231 water sources with remote cameras in a clustered-sampling design throughout Utah in 2006 and from 2009 to 2011. In association with camera sampling at water sources, we measured several site and landscape scale features around each water source to identify patterns in ungulate use informative for managers. We used model selection to identify features surrounding water sources that were related to visitation rates for male and female bighorn sheep, elk, mule deer, and pronghorn. Top models for each species were different, but supported models for males and females of the same species generally included similar covariates, although with varying strengths. Our results highlight the differing use of water sources by the sexes. This information will help guide managers when siting and reprovisioning wildlife water developments meant to benefit those species, and when prioritizing natural water sources for preservation or enhancement.

The capture of neonate ungulates has played an integral role in studies of habitat selection, phenology, survival, and other topics of ecological interest. However, neonates can be difficult for researchers to locate and capture. Neonate ungulates are born in habitats with reduced visibility, frequently spend time in a concealed, prone position, and may display cryptic coloration. In an attempt to improve researchers' likelihood of locating and capturing neonate ungulates, multiple capture methods have been developed. Much remains unknown about biases associated with capture methods and how to further improve capture methods once biases are understood. Our objectives were to determine if opportunistic captures of neonate mule deer (Odocoileus hemionus) bias estimates of litter size (Chapter 1) and to determine when searches for neonate elk (Cervus canadensis) should begin following parturition to maximize likelihood of capture while minimizing disturbance (Chapter 2). To complete our objectives, we analyzed data from 161 litters of mule deer and 55 attempted captures of neonate elk during 2019-2021 in Utah, USA. Estimates of litter size derived from opportunistic captures of mule deer were smaller than estimates derived from movement-based captures or captures completed with the aid of vaginal implant transmitters (VITs). The time elapsed between parturition and when searches were initiated for neonate mule deer did not influence estimates of litter size, but we could only analyze this relationship for VIT-aided captures within approximately 2 days of parturition. Until more data are available, we recommend that estimates of litter size for neonate mule deer be completed using movement-based or VIT-aided captures within approximately 2 days of parturition. When attempting to capture neonate elk, reducing the time elapsed between parturition and when searches were initiated resulted in a decreased search length, decreased distance traveled by the neonate, and increased likelihood of capture. We initiated searches as early as 3.6 hours post-parturition with no evidence of maternal abandonment and probability of capture was near or above 90% when searches were initiated within 10 hours of parturition. We recommend that searches for neonate elk be initiated 3.6-10 hours post-parturition. Future researchers can use utilize our results to perform captures of neonate ungulates that minimize bias, decrease disturbance, increase efficiency, and maximize the likelihood of capture success.