A CLOSER LOOK AT DENALI’S ALPINE WILDLIFE: ASSESSING THE INFLUENCES OF CLIMATE AND VEGETATION CHANGES ON SPECIES IN ALASKA

Author

Jennifer Lynn Wall

Year of Award

2024

Document Type

Dissertation

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Fish and Wildlife Biology

Department or School/College

W.A. Franke College of Forestry and Conservation

Committee Chair

Jedediah F. Brodie

Commitee Members

Erick Greene, Mark Hebblewhite, John Kimball, Paul M. Lukacs

Keywords

Arctic ground squirrel, biodiversity, climate change, collared pika, Denali National Park and Preserve, hoary marmot

Abstract

Climate change is amplified in polar regions and could have considerable consequences for biodiversity. Arctic and boreal regions, in particular, have warmed more than double the global average and are experiencing increasing precipitation, thawing permafrost, shrinking snow seasons, and increasing shrub- and tree-line encroachment. These changes are suspected to influence key alpine biodiversity, including species such as collared pikas (Ochotona collaris), hoary marmots (Marmota caligata), and Arctic ground squirrels (Urocitellus parryii). But, we have limited understanding of whether this is true and, if so, which factors drive distributional shifts in response to climate change. For this dissertation, I collected data in Denali National Park and Preserve, Alaska between 2019 - 2022. I first developed a framework combining a machine learning approach with integrated, Bayesian structural equation/ occupancy modeling to ascertain both the important predictors of occurrence and the causal pathways linking climate to occurrence for both pika and marmot distributions. My results suggest that pikas and marmots are not currently experiencing significant range shifts due to climate change but may begin to under additional warming. Building on this framework, I then combined a machine learning approach with distance sampling to assess ground squirrel distributions and abundance, and to identify areas where abundance is more sensitive to changing conditions. I found that local habitat conditions and snowpack play a role in ground squirrel population densities. This suggests that future declines in snowfall could affect this critical species, potentially leading to cascading, ecosystem-wide impacts. From here, I looked into pika behavioral patterns to assess the extent to which pikas moderate hyperthermia risks via thermal refugia and evaluated factors that could influence the plasticity of these responses. I found that activity levels were driven by surface rather than subsurface temperatures, and that pikas in higher quality patches could be more resilient to warming. As part of my work in Denali, I also established a pilot community science program to encourage park visitors to report sightings of alpine wildlife species. I found that community science data adjusted for sampling effort could pose a viable monitoring strategy for all three species when compared to traditional, randomized data collection approaches. Taken together, these results suggest that alpine wildlife are resilient to climate change at present in Denali, but that in the near future their persistence could be threatened by warming temperatures, shrub encroachment, and shrinking snow seasons.

Recommended Citation

Wall, Jennifer Lynn, "A CLOSER LOOK AT DENALI’S ALPINE WILDLIFE: ASSESSING THE INFLUENCES OF CLIMATE AND VEGETATION CHANGES ON SPECIES IN ALASKA" (2024). Graduate Student Theses, Dissertations, & Professional Papers. 12293.
https://scholarworks.umt.edu/etd/12293