BIRD MIGRATION UNDER FIRE: A MULTI-SCALE EXAMINATION OF MIGRATORY BIRD RESPONSES TO WILDFIRE AT STOPOVER SITES

Edwin Jacobo

Wildfire is an increasingly dominant driver of environmental change, yet its effects on migratory systems remain poorly understood, particularly across observational, ecological, and physiological scales. Migratory birds rely on spatially distributed stopover habitats to rest and refuel, making them especially vulnerable to disturbance-driven changes in habitat quality and availability. This dissertation investigates how wildfire reshapes migratory bird ecology by integrating three complementary perspectives: the observation process, occupancy dynamics, and individual refueling performance. First, I examine how wildfire influences observer behavior in citizen science datasets, which are widely used to study species monitoring at large spatial and temporal scales. Results show that fire alters both spatial sampling effort and temporal revisit patterns, with observers avoiding recently burned and high-severity areas. These shifts introduce dynamic biases that, if unaccounted for, can confound inference about species responses to disturbance. Second, I evaluate how wildfire affects stopover use by modeling occupancy dynamics of migratory birds. Using a dynamic occupancy framework, I estimate colonization and extinction probabilities to disentangle the underlying processes driving species occurrence. Colonization, defined as the probability that a species occupies a previously unoccupied site, and extinction, defined as the probability that a species is no longer present at a previously occupied site, are strongly influenced by time since fire. These results underscore the central role of post-fire succession in shaping the temporal availability and spatial distribution of stopover habitats. Finally, I assess how wildfire affects individual refueling performance using plasma metabolites as indicators of short-term energy balance. Refueling performance is highest in unburned areas and fire refugia and declines with increasing distance from fire, suggesting both direct and indirect effects, potentially mediated by habitat changes, individual displacement, and competition. Interactions with fire severity further indicate that more intense disturbances amplify these patterns. Together, these findings demonstrate that wildfire acts as a multi-scale driver of migratory dynamics by altering data collection processes, restructuring habitat use, and constraining individual net energy balance. This work provides a mechanistic framework for understanding how disturbance influences migratory species in an era of rapid global change.

BIRD MIGRATION UNDER FIRE: A MULTI-SCALE EXAMINATION OF MIGRATORY BIRD RESPONSES TO WILDFIRE AT STOPOVER SITES

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