Bat conservation and ecotourism: the case of two abandoned tunnels in Salamanca, Western Iberia

Abstract

Underground roosts play a key role in the conservation of cave-dwelling bats. In regions where natural roosts are scarce, human-made artificial roosts can host important populations of these species. The roosts studied in the present work are two railway tunnels abandoned in 1984 that have become one of the biggest cavedwelling bats roosts in the region. Several thousands of roosting bats were reported during summer in the 1990s, and more recently, in the mid-2010s, large groups of hibernating bats and maternity colonies were found in them (Lizana-Ciudad 2015, Hernández-Tabernero et al. 2016). Now, as a measure for local economic development, a hiking route following the railroad has been habilitated and it could threaten bat colonies if many visitors enter into the tunnels. In this work, we present the data of monthly monitoring carried out during 2018 and we propose conservation measures that would allow the coexistence of the touristic hiking route and the remarkable colonies of cave-dwelling bats that the tunnels host. This monitoring shows that the occupation of the roosts is very dynamic, with different species occupying each of them in different seasons. Overall, the longest tunnel is mainly a winter hibernaculum, while the shorter one is used as a breeding roost which hosts large colonies of bats. The most abundant species in the studied roosts were Miniopterus schreibersii, Rhinolophus ferrumequinum, Myotis myotis, and Myotis blythii. These roosts seem to be part of a large transnational network of underground roosts that are well known on the Portuguese side with very limited knowledge on the Spanish side. We hope by implementing simple measures, these roosts can be preserved whilst still maintaining the hiking route for visitor enjoyment and promoting the economic development of the area.