Spatially explicit comparison of abundances:
We additionally compared the local spatial distribution between time periods computing Kernel Density Estimates (KDEs, 25x25m kernel size) for the 111 species with >10 observations, using the raw detection points data from the spot maps (Calenge 2006). We performed first an overall comparison of the community spatial diversity, and second, a species-by-species spatial distribution comparison. First, to compare the community’s alpha-diversity between time periods, we standardized the KDEs for every species between 0 and 1 by dividing the density in each pixel by the maximum density for that species. We then added pixel by pixel densities of all species as an analogous diversity metric to Terborgh et al’s (1990) Figure 3. Second, we compared KDEs for each of the 111 species separately. We computed Pearson’s correlation coefficient using the Raster package (Hijmans 2020) for both community diversity and single species. For single species comparisons we tested whether the mean and median correlation coefficients were, on average, significantly higher than expected by chance using a non-parametric bootstrap test (Supplementary Information; Manly 2006).
Finally, we used a multi-model approach to determine if body mass, foraging strata, guild, and sociality explained single species’ spatial distribution similarity between time periods using a generalized least squares (gls) accounting for phylogenetic non independence, assuming a Brownian motion model evolution (Paradis & Schliep 2019). We fitted the data with all possible combinations of the independent variables using the MuMIn package (Barton 2018) with the Bayesian Information Criterion (BIC) as the model rank statistic. To propagate uncertainty in phylogenetic estimation, we repeated the model selection procedure using 100 randomly sampled trees from the ones used in previous analyses. We report the proportion of times that each candidate model is deemed as best using a delta BIC of at least 3 points (Taper & Ponciano 2016).