Between a Rock and a Hard Place: An Investigation of Rock Squirrel (Otospermophilus variegatus) Behavioral Response to Anthropogenic Change

As human populations grow, urbanization is transforming landscapes, leading to habitat loss and fragmentation. Urban adaptors, like rock squirrels (Otospermophilus variegatus), often exhibit behavioral flexibility in response to changing environments. While rock squirrels play vital roles in natural ecosystems, they also have the capacity to adjust to urban environments, which may involve altered habitat use, potential synanthropy, and changes in social dynamics. Urbanization may influence behaviors such as foraging and vigilance, which are essential for survival. However, there is still much we don’t fully understand about how these behaviors change in urban environments. For instance, the extent to which rock squirrels adjust their vigilance and foraging behavior in urban landscapes has remained unclear. My study sought to address this gap by examining the effects of urbanization on rock squirrel behavior at five different locations in central Texas along the eastern edge of the species geographic range. I examined vigilance and foraging behavior of rock squirrels at sites that differed in the amount of surrounding urbanization. Behavioral data, documented as the fraction of time spent in different activities, were extracted from videos obtained from wildlife cameras placed outside of occupied burrows at the study sites. For statistical analysis, the main unit of replication was a camera placed at a burrow on a given day (N = 234). I used nested ANOVA to test for differences in squirrel behavior among urbanization categories and study sites. In addition, burrows were mapped at each site to determine their spatial dispersion as either random, clumped, or over-dispersed. My results indicate that rock squirrels perceive and adjust their behavior to urbanized environments differently based on the level of urbanization. Specifically, total vigilance, the proportion of the total recorded video time (in seconds) per day during which the squirrel exhibited vigilance, was significantly greater in low (P = 0.0003) and medium (P < 0.0001) urbanization than in high urbanization sites, suggesting heightened alertness in less urbanized settings. Despite these heightened vigilance levels, no significant differences were observed in the hypervigilant picket-pin posture across urbanization levels. Additionally, squirrels in medium urbanization sites exhibited reduced foraging behavior compared to their counterparts in both low (P = 0.004) and high (P = 0.002) urbanization sites, possibly due to a trade-off between vigilance and foraging. Although burrows were never randomly dispersed, there was no clear association between spatial pattern (over-dispersed vs. clumped) with regard to level of urbanization. Overall, these results emphasize the behavioral complexity of rock squirrels adjusting to varying levels of urbanization. My research contributes valuable insights into the success of synanthropes in urban environments and enhances our understanding of wildlife behavior in rapidly changing anthropogenic landscapes.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Population and Conservation Biology

Grantor

Texas State University

Year dc:date.issued

2024

Author dc:creator

• Williams, Elisa

Advisor dc:contributor.advisor

• Veech, Joseph

Committee members dc:contributor.committeemember

• Aspbury, Andrea
• Schwinning, Susan

• behaviors
• urbanization
• rock squirrels
• anthropogenic change
• vigilance
• foraging behavior

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10877/19752

OAI identifier oai:identifier

oai:digital.library.txst.edu:10877/19752