The St Niclaus The Bishop church in Wleń has its place on the podium for the size of the Greater mouse-eared bat colony throughout Poland. In 2015, as many as 1400 adult bats were counted and together with their offspring their numbers may well exceed 2000.

The tin roof cover became damaged to the extent, where it was dangerous to bats and the church itself. The historic slate cover will be brought back. The renovation of the roof has just started and will take until half of April.