Restoring historical fire regimes increases activity of endangered bats

Background Fire suppression has altered ecological communities globally. Prescribed fire regimes strive to restore function to these fire-dependent ecosystems by mimicking natural fire regimes. Although fire frequency is a widely acknowledged component of fire regimes, the importance of fire seasonality for biodiversity is less clear but appears to play a critical role for a variety of taxa, particularly in the North American Coastal Plain. In subtropical Florida, USA, fire historically occurred primarily at the transition from the dry to wet season (early wet season: April to June) when dry fuel accumulation coincides with a high incidence of lightning. We investigated the effects of fire frequency and season on endangered Florida bonneted bats ( Eumops floridanus [G.M. Allen, 1932]), a species endemic to a region that evolved with frequent fires. Results We surveyed bat activity acoustically in 149 sites in fire-dependent vegetation communities (pine flatwoods and prairies), and evaluated the effects of fire frequency and seasonality, using burn records from the previous 18 years. Variation in bat activity was best explained by both fire frequency and season: bat activity decreased with early wet season (April to June) burn interval and increased with dry season (November to March) burn interval. Bat activity and foraging activity were highest in sites burned at > 3- to 5-year intervals during the early wet season. Conclusion Fires during the historic fire season at a moderate frequency (> 3 to 5 yr) appear to optimize habitat for bats in both pine flatwoods and prairies, likely through increases in roosts, flight space, and insect prey availability. It appears that Florida bonneted bats are fire-adapted and benefit from prescribed burn programs that closely mimic historical fire regimes. We encourage consideration of both fire frequency and seasonality when managing ecosystems with fire.