Date of Award:
Master of Science (MS)
Well-designed monitoring strategies are required to obtain accurate estimates of population abundance, which is important for evaluating conservation and management strategies. Obtaining abundance estimates using traditional survey methods, like aerial surveys, is not possible in all scenarios and can be expensive and risky. One survey method that has gained popularity in the last decade is fecal DNA-based capture-recapture (CMR). However, this method has not been evaluated on winter ranges or in snowy, winter conditions.
My first objective was to implement fecal DNA CMR to estimate abundance of mule deer in the Round Valley and Goodale winter survey areas in the Eastern Sierra Nevada, California, USA (2020). I compared precision and cost of fecal DNA CMR surveys to aerial mark-resight (MR) surveys for estimating abundance. I found that while aerial MR surveys had more precise estimates of abundance for our field situation, the cost was higher than for fecal DNA DMR. When comparing study designs with the same precision, simulations indicated that fecal DNA CMR typically had the lowest cost. I also found that fecal DNA CMR surveys were not effective in all areas. Therefore, when evaluating whether to apply this method, I recommend reviewing annual variation in weather, constraints on access to the winter range, and the scale of effort needed to achieve adequate coverage.
My second objective was to evaluate the relationship between GPS points (2017 – 2020), a kernel density estimator, and a resource selection function (RSF) to the number of pellet piles counted (2020) in the Round Valley survey area, California, USA. There was a positive relationship between the number of GPS points and the average kernel density per cell and the number of pellet piles. However, based on the large amount of variation in the pellet pile data not explained by the RSF, I conclude GPS-based RSFs are not the best method for generating strata. I recommend that managers use the number of GPS points or a kernel density estimator to inform fecal DNA CMR surveys. If GPS points are not available, I recommend that managers use the number of of pellet piles per survey cell to generate a well-informed stratification scheme, which can be used to improve the precision of abundance estimates from fecal DNA CMR surveys on large winter ranges.
Stewart, Andi M., "Comparing Fecal DNA Capture-Recapture Methods to Traditional Mark-Resight Methods for Estimating Abundance of Mule Deer on Winter Ranges" (2022). All Graduate Theses and Dissertations. 8593.
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