Aim: Many studies investigating the response of wildlife to disturbance focus predominantly on the effects of the disturbance alone but fail to account for the influence of ecosystem productivity in moderating the response of species and thus the resulting biodiversity patterns. We use Huston's dynamic equilibrium model (DEM) to explore the relationship between avian diversity and fire across the greater Rocky Mountain region of the western United States. This model provides the theoretical foundation to understand the distinct and interactive effects disturbance and productivity have on regulating species richness.

Location: We used avian monitoring data collected at 120 sites across Colorado, Idaho, Montana and Wyoming in the western United States from 2008 to 2016.

Methods: We used a Bayesian hierarchical multispecies occupancy model to predict species richness across fire and productivity gradients. Hierarchical models enable inference at the community and species level, accounting for imperfect detection, and providing a more accurate assessment of the ecological relationships.

Results: We found support of the hypotheses described by the DEM Avian species richness changed little across the fire severity gradient alone, though this relationship varies considerably when including the interaction of fire and ecosystem productivity. At lower latitudes, richness is greatest at intermediate levels of fire severity and productivity following the DEM. However, as latitude increases, the productivity at which richness is greatest also increases. Mean productivity increases with latitude across the study area, and we argue the changing regional levels of ecosystem productivity alters the relationships predicted by the DEM.

Main conclusions: Our results provide an important example of how relationships between richness and disturbance may be missed if viewed outside the context of other environmental factors, mainly ecosystem productivity. This highlights the importance of accounting for changing ecological context across broad spatial scales to ensure accurate assessments of disturbance–diversity relationships.