DISTRIBUTION AND POPULATION-DENSITIES OF 7 SPECIES OF BAT IN NORTHERNENGLAND

Distribution and minimum population densities for seven UK bat species known to be resident in northern England were calculated in an area c overing 2500 km(2). The species present were pipistrelle (Pipistrellus pipistrellus), brown long-eared (Plecotus auritus), Daubenton's (Myot is daubentonii), whiskered (Myotis mystacinus), Natterer's (Myotis nat tereri), noctule (Nyctalus noctula) and Brandt's (Myotis brandtii). Da ta were collected primarily from counts at summer roosts over the peri od 1983 to 1990. A total of 310 bat roosts were discovered within the study area. Of the 256 roosts at which the species present was identif ied, the majority, 127 (49.6%) were P. pipistrellus, with a mean mater nity roost size of 69.6 bats. A minimum population density of 12.6 bat s km(-2) was estimated for P. pipistrellus, based on summer (maternity ) roosts. The minimum population density estimate was higher than prev ious studies in northern England but substantially lower than those re ported in Scotland (18.2 bats km(-2)). The combined density of M. myst acinus, M. brandtii, and P. pipistrellus, which have similar foraging styles (15.8 bats km(-2)), is comparable to Scottish P. pipistrellus d ensities. The density of M. daubentonii was also lower than in Scotlan d, although the density of P. auritus was comparable. The majority of summer roosts for all species were found in buildings, except N. noctu la and M. daubentonii which used bridges/tunnels or trees.