The common noctule's short fur is dark brown after moulting in June (males) or July/August (females); later it changes to red-brown before the onset of winter.

[4] Characterized by its robust body and long, broad wings also has a distinctive, pointed snout and large ears that are essential for its echolocation capabilities.

Its range extends from the western parts of Europe to the eastern regions, including countries like Germany, Poland, and the United Kingdom.

[8] The common noctule is usually found at altitudes up to 2,000 meters, with recorded populations in a variety of habitats, from deciduous forests to agricultural landscapes.

[2][11][12] Mating season is in late summer in the wintering areas, and the females store the sperm in the uterus during hibernation until fertilization in spring.

[2] During early pregnancy in late April the females migrate north, as far as the Baltic region, to return to their natal maternity colonies and give birth after being pregnant for six to eight weeks.

The reproductive cycle of male bats seems to correspond directly to season and food availability and spermatogenesis can be affected by body condition.

[19] At the beginning of winter, usually in November (but this is strongly dependent on the ambient temperatures), N noctula start to hibernate in large groups with both sexes in the same roost.

Tree holes are not warm enough so they use caves, objects like church steeples or blocks of flats in Eastern Europe,[20] where they are most common hibernating bat species in the cities.

Nyctalus noctula uses echolocation to detect prey, emitting high-frequency calls that help it navigate and locate food in the dark.