Date of Award:
5-2024
Document Type:
Thesis
Degree Name:
Master of Science (MS)
Department:
Wildland Resources
Committee Chair(s)
Mary Conner (Committee Co-Chair), Kezia Manlove (Committee Co-Chair)
Committee
Mary Conner
Committee
Kezia Manlove
Committee
Tom Stephenson
Abstract
Survival of adult females is a key driver of population dynamics for ungulate species such as mule deer. Accurate survival estimates are therefore critical knowledge for managers trying to maintain ungulate populations. Additionally, understanding causes of mortality and their effects on populations is vitally important to enacting meaningful and appropriate management decisions. For this project, we estimated annual survival rates of six mule deer herds in the eastern Sierra Nevada, California, USA, and calculated rates of mortality for different causes to better understand factors affecting survival of mule deer in this region.
We estimated baseline annual survival using Cox proportional hazards models and also modeled survival as a function of selected covariates with a focus on body condition. Survival data were collected from GPS collars that were fit annually during captures. These collars notified the monitoring agency, California Department of Fish and Wildlife (CDFW), of a mortality event, at which point CDFW personnel investigated these sites to determine a cause of mortality. Using these data, we estimated annual cause-specific mortality rates for the detected causes using a non-parametric cumulative incidence function estimator. We combined results from these analyses to assess the effects of causes mortality on these populations by examining level of additive or compensatory mortality.
Overall, annual survival estimates were well below the level required for population stability. We found survival to be variable amongst herds and years, with accompanying different rates of mortality. Survival modeling showed a detectable positive effect of body condition on survival, meaning that increased body condition is related to increased survival. These results indicate the necessity of continued monitoring of these mule deer populations to assess any changes in already low survival estimates and provide information regarding other questions and research that could be conducted within this region.
Checksum
3661315299d73d1e76cbf5955aaaa3aa
Recommended Citation
Taylor, Glenden, "Survival and Cause-Specific Mortality of Mule Deer in the Eastern Sierra Nevada, California, USA" (2024). All Graduate Theses and Dissertations, Fall 2023 to Present. 198.
https://digitalcommons.usu.edu/etd2023/198
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