Data analysis
All statistical analyses were carried out in R version 3.6.1
(R-Core-Team, 2019). We standardized (scaled) all continuous covariates
by subtracting the mean and dividing by one standard deviation. We used
Pearson’s correlation tests to check for collinearity among continuous
variables, with a limit of r ≤ 0.6 (Zuur et al., 2010).
We used structural equation modeling (SEM) to test how interactions
among mesopredators (red fox, badger and pine marten) were affected by
large carnivores (wolf and lynx), land cover variables (proportion of
agricultural land and EVI), and human disturbance, as well as how these
interactions were affected by season (summer vs winter). SEM provides a
multivariate framework to develop and evaluate hypothesized networks of
causal relationships, estimating the relative strength of direct and
indirect paths within the system (Grace, 2006, Grace et al., 2012).