Statistical analyses
Data were analyzed using Statistical Package for the Social Sciences (SPSS) (version 26.0; SPSS, Inc., Chicago, IL, USA). Data were checked for normal distribution using the Shapiro-Wilk test. Data for marmot den characteristics that were not indicated as being normally distributed were log10-transformed to pursue normality and homogeneity of variances. We set terrains as fixed effects and replicates as a random effect. Factorial ANOVA (One-way ANOVA) analysis of variance with a least significant difference (LSD) test for multiple comparisons was used to compare various indicators of marmot den characteristics among different terrains. Figures were constructed using Origin 9.1.
Principal component analysis (PCA) was performed to study the relationship between the environmental variables (terrain and plant traits) and the den characteristics. PCA was performed using CANOCO version 5.0 (Šmilauer and Lepš 2014).