Minimum summer populations and densities of bats in N.E. Scotland, near the northern borders of their distributions

• Published in: Journal of Zoology
• Main Authors: Speakman, J. R., Racey, P. A., Catto, C. M. C., Webb, P. I., Swift, S. M., Burnett, A. M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1991
• Subjects: Pipistrellus pipistrellus
• Online Access: http://dx.doi.org/10.1111/j.1469-7998.1991.tb03820.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1469-7998.1991.tb03820.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-7998.1991.tb03820.x; https://zslpublications.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-7998.1991.tb03820.x

The contemporary summer populations of three species of bats, the common pipistrelle ( Pipistrellus pipistrellus ), the brown long‐eared bat (Plecorus auritus) and Daubenton's bat ( Myotis daubentonii ) in an area of 3200 km 2 . in N.E. Scotland (57°N), near to the northern borders of their distributions, were assessed by surveying nursery roosts. A total of 184 roosts were discovered between 1973 and 1989, and the species in occupation was identified at 147 of these. Of the roosts with identified occupants. 109 were occupied by pipistrelles. Most pipistrelle roosts were located close to the major rivers. The mean roost size in early summer for pipistrelles was 117 individuals. The larger roosts were predominantly (98.8%) female ( n = 165). Captured bats foraging on the rivers were only 67%) female ( n = 102) which indicated there was also a large population ofmales which the roost survey did not detect. The minimum density of females in the occupied habitat was estimated at 18.2 bats per km 2 . This contemporary population in the study area is much greater than was indicated in historical records from the 19th century. There was no evidence that the populations of pipistrelles, near to the northern border of their distribution. was reduced when compared with populations further south. Thirty‐four of the roosts were occupied by brown long‐eared bats. These roosts were located predominantly along a short(25 km). well wooded section of the River Dee. The mean roost size in early summer for brown long‐eared bats was 16.8 individuals. On average, these roosts were predominantly female(69.6%, n = 273), but contained a variable proportion of immature and occasionally mature males. The density of brown long‐eared bats in the occupied habitat was 1.66 bats per km2, less than a tenth the density of pipistrelles. Historically, this bat was more widespread and abundant in the area. There were only four identified roosts of Daubenton's bats, containing in total about 300 individuals. In all these cases, the roosts were ...