TY - JOUR AB - Bat activity is highly seasonal in temperate regions such as the British Isles, due to variation in temperature and food availability, leading to hibernation being commonly used as an overwinter survival strategy. Outside the hibernation season, European species of bats of several genera (Myotis, Barbastella and Plecotus) are known to take part in social swarming behaviours. These typically occur in autumn and are thought to be associated with mating prior to hibernation. Only one British species, the Brown Long-Eared Bat (Plecotus auritus) is known to swarm during spring. In this study, we used a combination of ultra-sonic acoustic monitoring and infra-red video surveillance, to describe seasonal activity patterns of Lesser Horseshoe Bats (Rhinolophus hipposideros) across spring-autumn of two years; 2015 and 2016. We identified a previously unknown spring peak in social activity, which occurred around caves which were known not to be used for hibernation, and occurred several weeks after the bats had emerged from hibernation in each year. Males examined during spring swarming were found to have well-developed epididymides, indicating that these individuals were in reproductive condition. This spring peak of activity is consistent with social swarming behaviour, and to our knowledge is the first record of swarming in this species and genus. We found no consistent evidence of equivalent swarming behaviour in autumn. In addition to the seasonal variation in activity, we detected positive effects of temperature and negative effects of rainfall on Lesser Horseshoe Bat activity, both during the spring swarming event, and across the study period. AU - Davison, Stephen P. AU - Thomas, Robert J. DA - 2017 DO - 10.14709/BarbJ.10.1.2017.03 J2 - Barb KW - Lesser Horseshoe Bats Rhinolophus hipposideros swarming behaviour social swarming meteorological effects temperature rainfall seasonal variation L1 - internal-pdf://3622558173/Thomas_et_al_2017.pdf LA - English M1 - 1 M3 - Journal article PY - 2017 ST - Apparent spring swarming beaviour of Lesser Horseshoe Bats (Rhinolophus hipposideros) T2 - Journal of Bat Research & Conservation TI - Apparent spring swarming beaviour of Lesser Horseshoe Bats (Rhinolophus hipposideros) VL - 10 ID - 15198 ER -