Who can cope with this environment? Occurrence and activity of bats on a sparsely wooded Mediterranean island

Abstract

A detailed knowledge of habitat use by bats is crucial for their effective conservation. Several studies have underlined the importance of forests for bats. This also holds for the European hot spot of bat diversity, the Mediterranean region, where human land use and, more recently, global warming, continue to promote a large-scale replacement of forests by sparsely wooded areas. To analyse how different bat species cope with this change in habitat availability, we studied bat activity and distribution on Asinara island, Sardinia. Call recordings were performed in different habitat types (forest, semi-open, open, settlement) and classified as echolocation, social call, or feeding, contacts. We checked for effects of habitat type, temperature, relative humidity, moonlight, and availability of potential prey insects on bat activity. Habitat type was the predominant factor explaining bat activity, which was highest at forest sites and lowest at open sites. Thus open-space foragers did not benefit from the ample presence of open areas. On the other hand, some edge and narrow space foragers reacted with habitat switching to forest loss. Thus, Rhinolophus hipposideros was predominant at semi-open sites, reflecting a flexible use of foraging habitats. Finally, contact types differed across habitat types with species-related preferences for social interactions and foraging activity. Our results suggest that sparsely wooded areas promote a change of bat community composition, and a loss of certain species, but also that a more balanced mix of habitat types by partial reforestation may help to maintain, and even increase, bat species diversity on Mediterranean islands.