Managing anthropogenic driven range expansion behaviourally: Mediterranean bats in desert ecosystems

Bat abundance and activity in deserts is affected by the distribution of water sources. Kuhl’s pipistrelle (Pipistrellus kuhlii) is one of several bat species that penetrated the Negev desert from Mediterranean habitats following anthropogenic development, and potentially competes with desert dwelling bats of the same guild. Pipistrellus kuhlii is an obligate drinker requiring a clear ‘swoop zone’ to drink. Thus, to reduce the competitive load that P. kuhlii has on desert dwelling species, we tested the effectiveness of obstructions above water surfaces, which we hypothesised would reduce the drinking ability of P. kuhlii, thus providing desert species a competitive edge. We obstructed the water surface of a swimming pool and successfully prevented P. kuhlii from drinking. Next, we manipulated natural water sources used by bats for foraging. This was done on two spatial and temporal scales: on 11 adjacent ephemeral water pools in Nahal Zin where each treatment was applied for several nights and on eight isolated natural pools in the Negev where treatments were alternated every 20 min. Manipulation of adjacent pools had no effect on activity levels of bats, but in isolated pools, the obstruction reduced the proportion of P. kuhlii activity by up to 15%. Although this tool cannot be used for management without further examination of its long-term effects on other bats and wildlife, this study does demonstrate its feasibility. Conservation schemes aiming to mitigate effects of undesirable species can be designed by identifying ecological differences between competing species, and manipulating the environment accordingly.