The common noctule is one of the largest species of bat in Western and Central Europe, measuring between 7 and 8 centimetres in length. It has yellowish to reddish-brown fur. Its face, ears and wing membranes are bare and blackish brown in colour. It has short, round ears and narrow wings with a wingspan of 33 to 46 centimetres.
The noctule lives in deciduous and mixed forests, parks, gardens and sometimes inhabited areas, including cities.
Noctules are active at dusk and night and roost during the day. In early summer, males and females live together in roosts, but after late May females begin to gather in maternity roosts of 20 to 50 (and rarely up to a few hundred), while the males remain solitary or form small bachelor groups. The bats roost in tree hollows, crevices, roof spaces and bat boxes. A migrant species, the noctule travels distances of up to 1,500 kilometres between its summer and winter territories. It feeds on flying insects such as moths and beetles.