Sensitivity of insectivorous bats to urbanization: Implications for suburban conservation planning

Effective conservation planning requires an understanding of species–habitat relationships across a diverse array of taxa, yet many studies typically focus on conspicuous fauna. Using systematic acoustic surveys, we examine the response of insectivorous bat species to urbanization and quantify species–habitat relationships to classify species in terms of their tolerance or sensitivity. Surveys were conducted in Sydney, Australia, during spring–summer of 2008 in 29 defined 25 km2 landscapes, across various land uses. We quantified bat–habitat relationships using local and landscape scale variables. We recorded 17 taxa across the urban gradient, with substantial variation in the tolerance and sensitivity of each species. The density of houses, landscape geology, the amount of bushland (ha) exclusively on fertile geologies and moth biomass were the most frequent predictors of individual activity, explaining more than 60% of variation in activity for some species. Importantly, the area of bushland on poorer soils was not a good predictor, highlighting the need for caution when interpreting results of large scale studies which do not account for variations in habitat productivity. Species-specific differences existed, although the majority of the assemblage was considered to be urban-sensitive. Many of these sensitive species were most active in fertile suburban habitats, with an average of 12–28% bushland cover within 5 km. Our study demonstrates the necessity to elucidate species-specific habitat relationships, and suggests bats would benefit from the conservation of productive suburban bushland remnants and riparian habitats, while improving connectivity to these areas via the maintenance of tree cover across the matrix.

► We model bat species–habitat relationships to determine sensitivity to urbanization.
► The majority of the bat assemblage is considered urban sensitive.
► Many species were present in suburban rather than well vegetated areas.
► Restoration efforts should focus on productive remnants and landscape connectivity.
► This will ensure a broader array of taxa are considered in conservation planning.