Lesser noctule
Nyctalus leisleri
Maksymilian Wojtkiewicz · Świętokrzyskie
Key facts in one look
- Size
- 12–20 g, wingspan 26–32 cm
- Diet
- Insectivore: moths, beetles, flies
- Status in Georgia
- Native, widespread
- Habitat
- Broadleaf and mixed forest, riverside woods, buildings
- Family
- Vespertilionidae
- Conservation
- LC / LC
The lesser noctule (Nyctalus leisleri) is a fast, narrow-winged forest bat: it comes out just after sunset and hunts at treetop height. It weighs 12–20 g and has a wingspan of 26–32 cm. In Georgia it is widespread: it has been found in Colchis, Adjara, Imereti, Kvemo Kartli and Kakheti, in Tusheti and in Abkhazia. The undersides of its arms are covered in fur, which is why it is also called the hairy-armed bat. It looks like the noctule, but it is smaller. A tree hollow or attic where it lives often gives itself away with loud chattering: if you hear it, do not disturb the colony.
Identification
Lesser noctule: how to identify it
A medium-sized bat with long, narrow wings, short rounded ears and a dark face. The fur is brown, darker at the base and golden or reddish at the tips. It looks very much like the noctule, which is larger and has fur of one colour along the whole hair.
Size is the main feature. The body is 5–7 cm long, the forearm 38–47 mm, the wingspan 26–32 cm and the weight 12–20 g. The noctule is larger, with a forearm of 47–52 mm and a weight of 18–40 g. Do not catch a bat to measure it: that is a job for specialists.
The fur is darker at the base than at the tips, while the noctule's hair is one colour along its whole length. On the shoulders and upper back the fur is long and looks like a mane. The undersides of the arms, along the wing bones, are covered in fur.
The face, ears and wings are dark. The ears are short and rounded, and the small inner flap of the ear, the tragus, is mushroom-shaped. Other noctules have the same tragus, so this feature only tells you the genus.
Its echolocation calls lie at 15–45 kHz, loudest at about 25 kHz. They can sometimes be heard by the human ear. On a bat detector they sound like a 'chip-chop', softer than the noctule's.
Colour
The fur is brown: golden or reddish-brown at the tips and darker at the base. The face, ears and wing membranes are dark.
Swatches are illustrative. Do not identify a species by colour alone.
Often confused with
The lesser noctule is mainly a forest bat. It prefers old, tall broadleaf and mixed forests with meadows and water, but it also lives in coniferous forests, parks and towns. It spends the day in tree hollows, mostly ones with a round entrance, and sometimes in bat boxes. It also lives in buildings: in attics, under roof tiles, behind window shutters and in disused chimneys. In Georgia it is widespread and known from the coast to Tusheti. It has been found in Kolkheti National Park, near Poti and Senaki, in the Adjaristskali valley and Kintrishi Nature Reserve, in Kutaisi and at the Tkibuli reservoir, in Gardabani Managed Reserve and the riverside forest at Rustavi, in the Alazani valley, in Tusheti near Beghela and in Abkhazia. It has also been recorded in caves, but it counts as a forest species rather than a cave bat.
The lesser noctule eats flying insects: moths, beetles and flies. It comes out just after sunset, a little later than the noctule. It flies fast and straight, at or below treetop height, with short, shallow dives. Sometimes it hunts around street lamps, where insects gather. It travels up to 10 km to feed, and in cold weather it does not feed at all.
The lesser noctule is a mobile species: it often uses a roost for only a few days before the colony moves elsewhere. Its seasonal movements can reach about 1,000 km. Before emerging it is very noisy, especially on hot summer days, giving loud, metallic chatter. It spends the winter in tree hollows, in crevices in buildings and sometimes in caves and tunnels. Mating runs from late summer to mid-autumn. At dusk a male leaves his roost, flies slowly around it within 300 m and calls loudly about once a second. People can hear this call. During this time the male does not feed and gathers a harem of up to 9 females. In summer the females gather apart from the males, usually in colonies of 20–50 animals. The young are born in mid-June, one or two; twins are more common in eastern Europe. It lives up to 9 years.
Globally the lesser noctule is rated Least Concern (LC, 2016). In Georgia the 2021 national assessment also rates it Least Concern (LC), with a stable population. Over most of its range it is still rare. It is most numerous in Ireland, where it is the third most common bat. Its threats are the decline of large insects, the loss of forests and hollow trees, and toxic chemicals used to treat timber in buildings. Because it changes roosts so often, it needs many hollow trees in one forest.
Related guides
Continue with related pages
Yes, and it is widespread. Data from 1835–2022 hold 87 records. It has been found in Kolkheti National Park, Adjara, Kutaisi and near Tkibuli, in the riverside forests of Gardabani and Rustavi, in the Alazani valley, in Tusheti and in Abkhazia. It spends the day in a tree hollow or a building, so you are most likely to notice it at dusk, flying fast over the trees.
By size and fur. The lesser noctule weighs 12–20 g and has a forearm of 38–47 mm; the noctule weighs 18–40 g, with a forearm of 47–52 mm. The lesser noctule's fur is darker at the base, while the noctule's hair is one colour along its whole length. Both have narrow wings and a mushroom-shaped tragus, so specialists tell them apart reliably.
It does not attack you, but do not touch it with bare hands. A bat bite can be tiny and easy to miss. Rabies cannot be ruled out by appearance, although most bats seen are not rabid. After a bite or scratch, wash the spot with soap and water for at least 15 minutes and see a doctor; in an emergency, call 112.
Stay calm and take children and pets out of the room. Close the doors to other rooms, open an outside window or door wide and switch off unnecessary lights. Then step back and give it time: a bat usually finds the way out by itself. Do not try to catch a flying bat.
It is not threatened. Globally it is Least Concern (LC, 2016), and Georgia's 2021 national assessment also rates it LC, with a stable population. Even so, it is rare over most of its range. It needs hollow trees and forests rich in large insects.
References
What this profile is based on
Species profiles are compiled from peer-reviewed literature and established biodiversity databases, and are reviewed as new taxonomic and conservation data become available.
Prepared by the Reptiles.ge editorial team from the sources listed here.
