A tale of two cervids: habitat selection and spatial ecology of Roosevelt and tule elk in California

Author

Adam S. MohrFollow

Graduation Date

Spring 2020

Document Type

Thesis

Program

Master of Science degree with a major in Natural Resources, option Wildlife

Committee Chair Name

Dr. Tim Bean

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Dr. Micaela Szykman Gunther

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Dr. Matthew Johnson

Third Committee Member Affiliation

HSU Faculty or Staff

Keywords

RSF, Water dependence, NDVI, IRG, Carrizo, Cervus, Nannodes, Roosevelti, Habitation, Risk perception

Subject Categories

Wildlife

Abstract

California’s Roosevelt (Cervus canadensis rooseveltii) and tule elk (C. c. nannodes) populations have experienced a remarkable recovery after over-hunting and habitat loss nearly extirpated them from the state. Greater clarity of Roosevelt and tule elk habitat selection patterns would help managers continue to effectively support the recovery of these two iconic subspecies. As the manner in which elk populations balance their competing resource needs is unique to each population (Skovlin et al. 2002), I have examined Roosevelt and tule elk habitat selection patterns in separate analyses and present these results in independent chapters. In both cases, I examine the role behavior can play in influencing habitat selection and fitness. Habitat selection models rely on a number of assumptions, which have proven difficult to test, particularly in regards to how behavior relates to perceived habitat suitability and resource availability. In this thesis, I address some of these assumptions by accounting for variation in elk behavior and changing resource conditions. My results demonstrate the effect of behavioral and seasonal resource variation on habitat suitability predictions and its importance for consideration in population management decisions.

Chapter 1 Abstract:

Habitat selection models often assume individuals within a population behave identically, which is problematic as behavior can vary non-randomly due to differences in how individuals perceive and respond to predation risk. I used GPS location data and a measure of human-tolerance (on a scale of “bold” to “shy”) to examine habitat selection patterns and make predictions about habitat suitability and potential abundance of Roosevelt elk in northwestern California, USA. Overall, elk selected for areas of open land cover types, in close proximity to forest edge, further from roads, and with gentle terrain. Shy elk remained closer to forest edge and further from roads compared to bold elk. Predicted elk habitat differed between bold and shy elk, but potential abundance estimates were relatively consistent at around 13,000-14,000 elk in the study area. Management decisions should be made at the level of individual elk groups when feasible, as decisions that affect an elk group’s tolerance of human disturbance will impact the availability and composition of suitable habitat, and ultimately may affect potential abundance.

Chapter 2 Abstract:

Climate change is expected to affect arid-system ungulate populations by altering the availability of critical resources, such as forage and water sources, and by increasing the frequency and severity of drought. The habitat selection patterns of the tule elk, a subspecies endemic to the Mediterranean climate regions of California, may provide insight into the behavioral adaptations which will allow affected ungulate populations to remain in their current geographic ranges. I used location data from GPS-collared tule elk to model their response to different environmental covariates including water sources, forage dynamics, human disturbance, and drought, across the wet and dry seasons. I found that tule elk behaved as central place foragers around water sources during the dry season, and that this behavior was likely tied to forage moisture content. During the wet season, elk appeared to be water independent and selected for high quality forage sources. These patterns were mediated by drought, as severe drought resulted in elk selecting for areas closer to water sources in the dry season and further from water sources in the wet season. My findings will help inform management decisions regarding artificial water source allocation and minimizing the effect of human disturbance on resource availability.

Citation Style

JWM

Recommended Citation

Mohr, Adam S., "A tale of two cervids: habitat selection and spatial ecology of Roosevelt and tule elk in California" (2020). Cal Poly Humboldt theses and projects. 374.
https://digitalcommons.humboldt.edu/etd/374