Professor University of Wisconsin Madison, Wisconsin
Fire is widely regarded as a potential stressor for bumble bee (Bombus) populations. However, there is surprisingly little empirical research that addresses how fire affects bumble bees, especially during sensitive life cycle stages like nest establishment and the initial stages of colony growth. To address this knowledge gap, we conducted abundance surveys of foraging and nest-searching queen bumble bees in spring-burned and unburned oak savannas in southern Wisconsin in the spring of 2022.
We encountered 8 bumble bee species native to Wisconsin during transect surveys of queens, including one occurrence of the endangered rusty-patched bumble bee (B. affinis). Preliminary analyses suggest marginal differences in the abundance of foraging queens between recently (spring) burned savannas and unburned savannas; we encountered approximately 2.5 times the number of foraging queens in burned areas compared to unburned areas. There were no differences in the abundance of nest-searching queens between savannas that had been burned and those that were not. Our research suggests that fire may improve habitat for bumble bees in the early spring, at least for foraging queens.
