The northern Idaho ground squirrel (Uricotellus brunneus) is a federally threatened mammal endemic to Adams County and Valley County, Idaho. Northern Idaho ground squirrels spend the spring and summer months actively foraging for food and reproducing. As winter approaches, the squirrel creates a hibernaculum where it spends approximately 8 months hibernating. A recent study suggested that hibernacula locations are more likely to be in areas near fallen trees or large branches. The cause of this pattern is unknown. Hypotheses include: 1) logs may provide insulating benefits during hibernation, 2) logs may provide protection from predators, and 3) logs may be an indicator of other important hibernacula attributes such as deeper soil. The objective of this project was to compare the proximity of logs between hibernacula and random points. Our study sites consisted of three, 4-hectare plots in Payette National Forest in central Idaho. We created a minimum convex polygon (MCP) with a 50-meter buffer for all hibernacula locations within the study sites. Any log within the MCP or buffer with a diameter greater than 10 centimeters and length greater than 2 meters had its length, maximum diameter, bearing, class and UTM coordinates recorded. We used ArcMap 10.6 and Microsoft Excel for data analysis.
Results/Conclusions
We compared the following 5 metrics between hibernacula and random points: mean, maximum and minimum nearest distance, and length and diameter of the nearest log. Based on results from one study site, logs were closer to hibernacula locations (mean nearest distance = 9.79 meters) compared to random points (mean nearest distance = 31.2 meters). Logs nearest to hibernacula points had a mean length of 6.78 meters and logs nearest to random points had a mean length of 8.07 meters. The maximum diameter of logs nearest to hibernacula points was 25.3 centimeters and 34.6 centimeters for logs nearest to random points. The results generally support the idea that hibernacula sites are closer to logs than random points. We did not detect differences in the mean length or mean maximum diameter of a log between hibernacula and random points. Additional analyses of log characteristics and proximity to hibernacula is important to understand in the context of habitat management for this rare species.