First record of a Nathusius' pipistrelle (Pipistrellus nathusii) overwintering at a latitude above 60°N

Highly mobile species are considered to be the first to respond to climate change by transforming their ranges of distribution. There is evidence suggesting that Pipistrellus nathusii, a long-distance migrant, is expanding both its reproduction and overwintering ranges to the North. We recorded the echolocation calls of bats at 16 sites in South-Western Finland on two consecutive winters, and detected calls of P. nathusii at one of the sites throughout the latter winter. To our knowledge, this is the northernmost observation of an overwintering P. nathusii, and further evidence that the species is already responding to climate change.