Resilient responses by bats to a severe wildfire: conservation implications

Wildfires shape ecosystems globally, yet little is known on their effects on wildlife distribution and spatial behaviour. We used bats as models to test the effects of fire on ecosystems because they are multi-habitat specialists and feature ecological and life traits such as behavioural plasticity and longevity that make them able to respond to both short- and long-term environmental changes. We aimed at testing the effects of a severe wildfire on a Mediterranean bat assemblage in terms of occupancy, activity and individual fitness. Here, we measure the effects of fire on activity levels and occupancy by a Mediterranean bat assemblage at the Vesuvius National Park, in Southern Italy, over 4 years, encompassing a year when a severe wildfire occurred. By comparing bat occurrence and activity at burnt versus unburnt sites with a Before-After/Control-Impact approach, we found that bat responses to wildfires are species specific and depend on the time elapsed since the fire. Species that rely more strongly on forest areas showed a strong short-term adverse response in terms of occupancy and activity, while species adapted to open habitats showed no response 1 year after the wildfire. However, most species showed a general positive effect due to the passage of fire 2 years after its occurrence, probably because of vegetation regrowth. The wildfire event was also associated with reduced reproduction in at least one species, and to worse individual body conditions 1 year after the wildfire. Our results show that most bats in a Mediterranean ecosystem show resilience to the occurrence of fire, yet many species show negative short-term responses by altering their spatial behaviour and decreasing their investment in reproduction. Future increases in fire occurrence and intensity due to climate change may alter bat assemblages and impair population viability in the long term, hampering the fundamental ecosystem services provided by structured bat communities.