Here, we hypothesized that ENM contrasts, which we define as the difference in habitat suitability between two different ENMs, might also predict variation in performance on different hosts. We created ENM contrasts by subtracting the logistic-transformed ENM output for parasite occurrence on a focal host species from the all host species-occurrence model for each grid cell. Higher potential for specialization on a given host is indicated by more negative values in ENM contrasts (lower bound of -1) and lower potential for specialization is indicated by more positive values (upper bound of 1). Values close to zero can be interpreted as locations where generalist parasites are likely. We calculated the average value within 50 km of S. hermonthica locations from empirical studies as a measure of predicted specialization by ENMs, but similar values were observed at a range of distances (Fig. S3).