The ability to capture and monitor neonate ungulates has been enhanced by vaginal implant transmitters (VITs). Improving capture methodology when using VITs will further increase the likelihood of capturing neonates. We analyzed data from 55 attempted captures of neonate elk (Cervus canadensis) in Utah, USA, during 2019-2020 to determine when searches for neonate elk should begin to maximize likelihood of capture while minimizing disturbance. Reducing the time elapsed between parturition and search initiation 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. Probability of capture was near or above 90% when searches were initiated within 10 hours of parturition. We recommend that researchers initiate searches 3.6-10 hours post-parturition to allow for capture attempts that are effective, efficient, and minimally disruptive.

Age of individuals is an intrinsic demographic parameter used in the modeling and management of wildlife. Although analysis of cementum annuli from teeth is currently the most accurate method used to age ungulates, the age of live ungulates in the field can be estimated by examining tooth wear and tooth replacement patterns. However, there may be limitations to aging based on tooth wear as the rate of tooth wear likely varies among individuals due to factors such as age, diet, environment, and sex. Our objective was to determine the reliability of estimating age for mule deer based on tooth wear and tooth replacement patterns. We compared ages estimated by tooth wear (collected at time of capture for a statewide monitoring effort) to ages determined from cementum analysis (from teeth collected after mortalities of radio-tracked animals from the monitoring effort). Accuracy was high; ages estimated from tooth wear were within one year of cementum ages >75% of the time when aged by experienced observers. Bias in accuracy for estimates of age was low but slightly biased toward underestimation (i.e., 0.6 years on average)—especially as cementum age increased. Our results indicate that aging mule deer using patterns in tooth wear can be reliable if observers estimating age have experience using this method.

The capture of neonate ungulates allows for the collection of valuable ecological data, including estimates of litter size. However, varied methods used to capture neonate ungulates can result in sampling biases. Our objective was to determine if opportunistic captures of neonate ungulates (i.e., locating neonates by visually scanning for adult females displaying postpartum behaviors) bias relative estimates of litter size and investigate potential causes if a bias does exist. We analyzed data from 161 litters of mule deer (Odocoileus hemionus) sampled using three different capture methods during 2019–2021 in Utah, USA. Estimates of litter size derived from opportunistic captures were smaller than estimates derived from movement-based captures or captures completed with the aid of vaginal implant transmitters (VITs). Age at capture was inversely related to estimates of litter size and likely influenced the detection bias associated with opportunistic captures. Neonates captured opportunistically were not older than neonates captured using movement-based methods, but were older than neonates captured with the aid of VITs. Distance between neonates from the same litter did not influence estimates of litter size. Researchers should be aware of the biases associated with different capture methods and use caution when interpreting data among multiple capture methods. Estimates of litter size derived from opportunistic captures should not be compared to estimates of litter size derived from alternative capture methods without accounting for the detection bias we observed.