The distribution of Daubenton's bats (Myotis daubentonii) and pipistrelle bats (Pipistrellus pipistrellus) (Vespertilionidae) in relation to small-scale variation in riverine habitat

The distribution of foraging Myotis daubentonii and Pipistrellus pipistrell us bats (Vespertilionidae) was investigated along an upland river in relati on to the smoothness of the water surface and the extent of bankside vegeta tion. It was found that both bat species significantly preferred sections o f the river with smooth water surfaces and trees on both banks. The abundan ce of insects flying just above the water surface was also significantly gr eater in sections with a smooth water surface with trees on both sides. The distribution of bats thus probably correlated with the higher densities of insects, and may also have been related to the avoidance of noise from rou gh water areas which interferes with echolocation. The results suggest that in upland river systems, maintenance and enhancement of bankside vegetatio n and tree cover in association with the maintenance and enhancement of a m osaic of water surfaces (to include some smooth water where trees are prese nt) will increase the value of the riverine habitat to bats. (C) 1999 Elsev ier Science Ltd. All rights reserved.