Lutra 50(2)_Ciechanowski et al_2007

Rare or underestimated? – The distribution and abundance of the pond bat (Myotis dasycneme) in Poland

The paper summarises the distribution and abundance of the globally vulnerable and nationally endangered pond bat (Myotis dasycneme) in Poland and is based on all the available published and unpublished data. The species was recorded in 105 UTM squares, scattered across almost the whole of Poland. In addition fossil remains, mostly from the Holocene age, were found in 13 squares. Evidence of pond bat breeding (nursing) was obtained from 10 UTM squares, restricted to the lakelands of northern Poland and the valleys of the large rivers in the central part of the country. Only two nursery roosts, used respectively by a maximum of 481 and 391 individuals, were found. The remaining summer records (41 UTM squares) were sightings or captures of adult males, non-breeding females or unsexed individuals and were widely dispersed in areas located far from known reproduction sites. The summer roosts (n=21) were located mainly in buildings, bridge crevices and bird and bat boxes. Sixty-seven hibernation sites of pond bat were found, mainly in old fortifications, cellars and caves. 63% (n=42) of them were used by single individuals and only three held 10 or more individuals (maximum n=34). In the two regularly monitored sites the number of pond bats has fluctuated in recent years and in one site it even increased. Most of the available bat data (winter censuses, bird and bat boxes, owl pellets, road casualties, fossil remains, mist netting) shows that pond bats account for less than 1% of the Polish bat assemblages. However this figure reached 2.1 - 2.7% (and in one instance 17.5%) of the total number of bats netted in some regions of the northern lakelands. Many areas that are potentially attractive for breeding populations of pond bat have not yet been surveyed, suggesting that the species in Poland may be much more common and numerous than previously thought.