This map, adapted from Tronstad et al. (2025), illustrates the changes in habitat suitability for Bombus occidentalis across Oregon. Areas that experienced an increase, decrease, or no significant change to habitat suitability over time are highlighted using a color gradient with blue being an increase, white being no siginificant change, and tan being a decrease in suitable habitat. The extensive white regions stretching through the central part of the state indicate areas where habitat suitability remained largely stable between the pre-1998 and post-1998 models. In contrast, certain regions, particularly in southwestern Oregon, show notable decreases in habitat suitability. Interestingly, only a small area exhibited an increase in suitability.

Habitat change was calculated by subtracting the pre-1998 model’s suitability score from the post-1998 model’s score for each location, producing a change value between –1 and +1. Areas were considered unchanged if this difference is between ±0.1, meaning small shifts in model score were treated as essentially stable rather than true increases or decreases. Areas with changes greater than +0.1 were classified as increases in suitable habitat, while those with changes less than –0.1 were classified as decreases. A ±0.1 threshold was chosen to capture meaningful changes in habitat suitability while still being sensitive enough to detect relatively small but potentially important shifts across the landscape.

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