APPENDIX 3. One twodimensional (LonMid, LatMid) and two onedimensional (depth + mindist) smoothing splines (solid line) of the fitted GAM (xaxes) and the response variable, density of fin whale schools. Each explanatory variable was allowed up to 9 df, and degree of smoothing was automated by mgcv. Each xaxis contains a rugplot, where small ticks mark observed values. Regions of high whale density are identified by values above zero on the yaxis. Note the different scale of each yaxis, which is labeled s(covariate name, estimated degrees of freedom). The dashed lines represent ±2 standard errors, or roughly 95% confidence intervals.
