Giant noctule
Nyctalus lasiopterus
Sultangareyeva Liliya · Meleuzovskiy rayon
Key facts in one look
- Size
- 41–76 g, wingspan 41–46 cm
- Diet
- Insectivore: beetles, moths; small birds during migration
- Status in Georgia
- Native, rare
- Habitat
- Broadleaf forest, old hollow trees
- Family
- Vespertilionidae
- Conservation
- VU / VU
The giant noctule (Nyctalus lasiopterus) is Europe's largest bat: it weighs 41–76 g and has a wingspan of 41–46 cm. It is one of the few bats that hunt birds: during bird migration it catches small songbirds travelling at night, right in the air. The rest of the time it eats large beetles and moths. In Georgia it is rare and known from the Borjomi Gorge, Lagodekhi, the Iori and Jandari area, Anaklia and Abkhazia. It looks like the noctule, but it is much larger. If you find an exhausted bat on the ground, do not pick it up with bare hands.
Identification
Giant noctule: how to identify it
A large bat with narrow, long, pointed wings and uniform reddish-brown to dark brown fur. Size is the main feature: there is no larger bat in Europe. The noctule has similar fur and wings, so the two species are told apart mainly by size.
Size is the main feature. The body is 8.4–10.4 cm long, the tail 5.5–6.6 cm, the forearm 62–68 mm, the wingspan 41–46 cm and the weight 41–76 g. The noctule has a forearm of 47–52 mm and weighs 18–40 g. Do not catch a bat to measure it: that is a job for specialists.
The wings are narrow, long and pointed, built for fast flight in open sky. A band of fur runs along the front edge of the underside of the wing. The wing membrane is thin and tears easily, but the damage heals.
The muzzle is broad, and the ears are short and rounded, with folds of skin. The small inner flap of the ear, the tragus, is short, broad and mushroom-shaped. Other noctules have the same tragus, so this feature only tells you the genus.
It gives very loud echolocation calls, with the highest frequency at about 18–19 kHz. Its calls lie beyond the hearing range of birds, which helps it hunt them in the air. Its eyes are poorly developed, but its hearing and sense of smell are keen.
Colour
The back is uniform, from reddish-brown to dark brown, sometimes straw-red or chestnut-red. The belly is slightly paler than the back. The fur behind the ears is darker.
Swatches are illustrative. Do not identify a species by colour alone.
Often confused with
The giant noctule is a forest bat that roosts in trees all year round. It spends the day in tree hollows, most often in old, hollow oaks and beeches, and in pines when there is no other choice. It does not rely on one tree: different trees serve different purposes, and it uses a whole network of them. In Europe it lives in broadleaf forests. It hunts along forest edges and over water. In Georgia it has been recorded in both the east and the west of the country. It was found in the Borjomi Gorge and around Bakuriani, in Lagodekhi Nature Reserve, in the riverside forest of the Iori, around Jandari, at Anaklia, at Bakhmaro and in Abkhazia. Dated records span 1971–2018.
The giant noctule eats mainly large insects: rhinoceros beetles, longhorn beetles, cockchafers, stag beetles and moths. During bird migration, however, it switches to small songbirds that travel at night and catches them in the air. Blood and dropping analyses found robins, leaf warblers, Sylvia warblers and redstarts among its prey. In one study, birds made up more than 80% of its diet during migration. No one has yet seen it attack a bird, probably because it hunts at night, more than 700 m above the ground.
The giant noctule leaves its roost only when it is completely dark. It starts hunting high up and then comes down closer to the ground. In trees it usually lives in ones to threes, often within colonies of noctules and lesser noctules. Less often it forms colonies of 8–13, sometimes up to 50 animals. The groups are not fixed: animals move from tree to tree and join several groups. Its hunting range is about 2,500 km², one of the largest of any bat. Little is known about its breeding, because it is rare and poorly studied. Pregnancy lasts about two and a half months, and there are usually two young. It can travel far, so the ratio of females to males differs greatly from place to place. Its enemies include the barn owl and the eagle-owl, which hunt at the very time the giant noctule comes out to feed.
The giant noctule is Vulnerable both globally (VU, 2016) and in Georgia: the 2021 national assessment also rates it Vulnerable (VU), and its population trend is unknown. It is not on Georgia's 2014 Red List. The main threat is the loss of old, hollow trees. In recent years wood has been used more as fuel, and logging has increased. Its numbers are very hard to estimate because of the way it lives, and the reasons why it is so scarce are unknown. Protection is therefore still general: keeping old, hollow broadleaf trees and studying the species.
Related guides
Continue with related pages
Yes, but it is rare. Data from 1835–2022 hold only 23 records. It has been found in the Borjomi Gorge, Lagodekhi Nature Reserve, around the Iori and Jandari, at Anaklia, at Bakhmaro and in Abkhazia. It spends the day in a tree hollow and comes out in the dark, so it is hard to see.
Yes. During bird migration it catches small songbirds travelling at night in the air. Blood and dropping analyses showed this: robins, leaf warblers, Sylvia warblers and redstarts were found among its prey. In one study, birds made up more than 80% of its diet in this period. The rest of the time it eats large beetles and moths.
By size. The giant noctule weighs 41–76 g, with a forearm of 62–68 mm and a wingspan of 41–46 cm. The noctule weighs 18–40 g, with a forearm of 47–52 mm and a wingspan of 32–40 cm. Both are reddish-brown and have narrow, pointed wings. Specialists tell them apart reliably; do not catch a bat to do it.
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.
It is a vulnerable species. Globally it is Vulnerable (VU, 2016), and Georgia's 2021 national assessment also rates it Vulnerable (VU). It is not on Georgia's 2014 Red List. The main threat is the felling of old, hollow trees, so keeping such trees matters most for it.
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.
