First records of hibernating Leister’s bats Nyctalus leisleri in Belgium and the Netherlands

摘要

Leisler’s bat (Nyctalus leisleri) is a rare, but widespread species in Belgium and the Netherlands. The species typically roosts year-round in tree cavities, although bat boxes are also sometimes used (Boston et al. 2020). While Leisler’s bat is recorded across the region, known maternity roosts are limited to larger, ancient forest fragments in the south of Flanders and the eastern part of the Netherlands. Leisler’s bat is recorded from April to October (waarnemingen.be and waarneming.nl), but virtually nothing is known about hibernation of the species in Belgium and the Netherlands. In Europe the species is often considered migratory (Boston et al. 2020). Recoveries of ringed individuals (mainly in Germany and Spain) revealed that individuals from northwestern Europe migrate in a southwesterly direction, with several recoveries over more than 1500 km in the Iberian peninsula (Hut-terer et al. 2005, Steffen et al. 2007). Ohlendorf et al. (2001) describe a case of a female Leisler’s bat that was ringed in Germany in May 1998, recaptured in Spain in September 1999 (more than 1500 km to the southwest) and then recaptured in May 2000 at the original ringing site in Germany. Although data is sparse, many of such long distance recoveries were females (Roer 1989, Wohlgemuth et al. 2004), indicating a possible sex difference in migratory behaviour, as has been observed in nodules {Nyctalus noctula) (Dechmann et al. 2014, Lehnert et al. 2018). The migratory behaviour of Leisler’s bat is also supported by stable isotope analyses. By examining hydrogen isotopes in fur keratin, Voigt et al. (2012) showed that wind turbine victims of this species found in Germany likely originated from the Baltic states or Belarus. A previous record also indicated migratory behaviour in the Belgian population. In autumn 2010, a ringed adult female was found in the province of Namur. This individual was ringed in autumn 2007 in Lizaso, Spain - over 960 km to the south-west of the recovery site (Alcalde et al. 2013). Winter records of Leisler’s bat are also known from northwestern and Central Europe, for example from Germany and Switzerland, in tree cavities, bird and bat boxes (Kulzer et al. 1987, Roer 1989, Kretzschmar et al. 2005, Ohlendorf et al. 2010, Kohnen et al. 2020, Windeln 2023).