FIGURE 6. Sensitivity of seabird distribution to presence or absence of rats on nearby islands. Boosted Regression Trees (BRT) relative contribution, in the vicinity of rat-free island (a-c) or rat-infested islands (d-f). Variables with less than 5% contribution were not included in the plots. Partial dependence plot (g-i) of the effects of rat-free (blue lines) and rat-infested (red lines) islands. Contribution of Distance to infested islands on Procellariidae was not >5% therefore it was not retained. Stippled line denotes location of 1st breaking point threshold for each partial plot. Breaking points for Laridae were 63.6 km and 100.7 km from rat-infested islands, and 47.5 km and 67.4 km from rat-free islands. Breaking point for Sulidae were 60.5 and 176.4 from rat-infested islands and 16.5 and 188.1 from rat-free islands. Breaking point for Procellariidae were 73.5 and 175.3 from rat-infested islands and 82.9 and 102.6. The 2nd breaking point on each partial plot was no significant, hence no plotted (Appendix S3). SST = sea surface temperature, SLA = sea levels anomalies, CHL = chlorophyll-a, Distance = distance to the nearest rat-free or rat infested island, depending on the model, Area = area of the nearest rat-free or rat infested island.