Graduation Date

Winter 2024

Document Type

Thesis

Program

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

Committee Chair Name

Richard Brown

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Barbara Clucas

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Andre Buchheister

Third Committee Member Affiliation

HSU Faculty or Staff

Keywords

American pika, pikas, Ochotona princeps, Lassen National Forest, Northern California, nocturnal activity, nocturnal, behavior, nocturnality, Great Basin, diel, activity patterns, temperature, low elevation, rock complexity

Subject Categories

Wildlife

Abstract

The American pika (Ochotona princeps) is a charismatic mammal species adapted to occupy rockslides and boulder fields in western North America. Historically monitored due to their climate sensitivity, pikas have experienced extirpations along their lower range margins—driven by chronic and acute temperature stress—prompting increased concern and monitoring over the risks posed by anthropogenic climate change. Traditionally considered an alpine species, pikas occupy a wide range of elevations, with those at lower elevations exhibiting higher rates of nocturnality than their counterparts at higher elevations. Temperature is hypothesized to be the driver, but this has yet to be confirmed. Pikas exhibit diverse preferences for microhabitat features; however, previous studies have not assessed how spatial microhabitats may influence the temporal variability in pika surface activity patterns. This study evaluated how variations in local microhabitat conditions affected pika overall and nocturnal activities. From July to October 2023, motion-capture cameras and temperature loggers recorded activity at 29 pika activity centers across three lower-elevation locations in Lassen National Forest, California. Habitat surveys documented rock, vegetation, and activity center characteristics. Lunar illumination and visitations by sympatric species were also recorded. Four generalized linear mixed effect models (GLMMs) assessed the influence of environmental and habitat variables on pika surface activity patterns. These models analyzed the daily count of pika overall and nocturnal behavioral events, considering data from all activity centers as well as focusing specifically on the five haypiles with the highest observed activity to identify key drivers of behavior. Random variability among pikas explained most overall and nocturnal activity, underscoring the significance of unmeasured ecological factors, localized environmental conditions, and behavioral flexibilities. Still, temperature was weakly associated with surface activity, with warmer daytime surface temperatures related to increased nocturnal behavior, while sustained daily temperatures ≥25.5°C suppressed surface activity altogether. Rock complexity was positively related to overall and nocturnal behaviors and pikas demonstrated increased activity levels at structures with higher complexity. Nevertheless, further analysis is needed to disentangle the relationship between rock complexity, temperature, and pika surface activity patterns. This study contributes to the growing body of literature indicating that pika surface activity patterns can vary in diel timing in response to various ecological factors and environmental conditions.

Citation Style

Journal of Wildlife Management

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