Well-designed monitoring strategies are required to obtain accurate estimates of population size and vital rates, which are important for evaluating conservation and management strategies. Fecal DNA-based capture-recapture has been successful in estimating population abundance and vital rates of ungulates where individuals congregate around a resource. However, when little is known about the population’s distribution, determining where and how to sample effectively can be a difficult and costly task. We propose using resource selection functions (RSFs) as a tool to improve the implementation of fecal DNA mark-recapture surveys on large-scale landscapes. We used GPS location data from the winter range for two mule deer (Odocoileus hemionus inyoensis) populations along the eastern slope of the Sierra Nevada Mountains in an RSF to delineate high, medium, and low habitat use strata. We used these strata in a stratified random sampling design to select sites for fecal DNA capture-recapture surveys. We will compare results from RSF-based stratified random sampling to simple random sampling. Our primary metrics of interest are estimates of abundance and its precision. We also will compare number of samples collected, number of unique individuals, and recapture success for both sampling strategies to robustly determine if RSF analysis can improve sampling design.
Results/Conclusions
Based on simple random sampling, fecal DNA mark-recapture surveys were completed in winter 2019 on two populations of mule deer, Round Valley and Goodale. In Round Valley, 326 samples were collected and 196 unique individuals identified. Based on capture-recapture analysis, abundance was 3,588 deer with a CV of 18%. In Goodale, 87 samples were collected and 63 unique individuals identified. Capture-recapture analysis could not be completed due to low sample size. Fecal DNA capture-recapture surveys based on stratified random sampling from RSF analysis are currently underway. In Round Valley, 570 samples were collected, increasing the sample size by 57% compared to simple random sampling. Goodale sampling will be completed in March 2020 and preliminary results will be available by August 2020. Based on Round Valley’s preliminary results, RSFs show promise to improve sampling design for fecal DNA mark-recapture. The increased number of samples collected should improve the precision of abundance estimates. If collection and precision of abundance estimates are improved, fecal DNA capture-recapture can be used as a non-invasive monitoring alternative to traditional methods that require expensive and often invasive capturing and marking, and/or expensive helicopter time to count ungulates on winter ranges.