Post-flight initiation distance response and correlation analysis
Given that squirrels could only take one of two escape options, we first ran a binomial model exploring the factors that influenced whether a squirrel sheltered or not (Table S2) and then we ran separate bivariate models to analyze these disparate post-FID responses and their among-individual correlations with FID. Specifically, one model contained FID and shelter emergence time as response variables, and the second model contained FID and stop look distance as response variables. Shelter emergence time and stop look distance were both modelled using a Gamma distribution and log-link function. Both bivariate models contained the same set of predictors (year, sex, life stage, trial number, home site activity score and trappability). Walker identity and squirrel identity were included as random intercepts. To estimate the correlation between an individual’s FID and post-FID response, we extracted the posterior mean among-individual random intercept correlation from each model respectively. We also estimated the repeatability (R) of each post-FID response by extracting the variance components from their respective models and using the following formula for Gamma distributed variables (Nakagawa et al. 2017):
\begin{equation} R=\ \frac{V_{\text{ind}}}{V_{\text{ind}}+V_{\text{obs}}+ln(1+\frac{1}{\upsilon})}\nonumber \\ \end{equation}
where Vind is the among-individual variance, Vobs is the among-observer variance, and \(\upsilon\) is the shape parameter of the gamma distribution.