Characteristics of transition roosts of the lesser horseshoe bat Rhinolophus hipposideros - a case study from South-Western Poland.

During the transitional period, i.e., during the autumn and spring migrations, the lesser horseshoe bats Rhinolophus hipposiders (Borkhausen, 1797) use transition roosts. In this paper, we try to characterize this type of roost using the example of the basement of an old distillery. The results of many years of monitoring the number of bats (2007-2020), microclimate analysis prevailing in the bat roost, and the dynamics of bat numbers conducted at the turn of 2015/2017 were also presented. During this period, 1 to 13 lesser horseshoe bats were recorded in the roost. Most bats were found in September, October, and April. Bats stayed in the roost at some distance from the inlet, preferring places with a temperature of 10-14°C. Bats were significantly more often found in the central chambers of the basement, chambers number 2 (F = 3.07; p=0.041). However, there was no statistically significant higher intensity (more bats) in the use of the roost (basement) between spring and autumn (F = 1.237, p=0.272). No statistically significant correlation was found between the number of lesser horseshoe bats in the roost and the temperature outside. In this roost, the Brown long-eared bat Plecotus auritus (Linnaeus, 1758) was also noted. Results of ringing bats` recapture show that lesser horseshoes bats can be attached to their transition roost and can spend longer periods there. The bat ringed in the transition roost wintered in a cave, 19.5 km away, while they spent the summer in the colony 3 km away. [ABSTRACT FROM AUTHOR]