Western barbastelle
Barbastella barbastellus
Gintautas Steiblys · Kauno
Key facts in one look
- Size
- 5–14 g, wingspan 24.5–28 cm
- Diet
- Insectivore, almost only moths
- Status in Georgia
- Rare, 63 records
- Habitat
- Old forests, caves in winter
- Family
- Vespertilionidae
- Conservation
- VU / NT
The western barbastelle is a moth specialist: in some countries moths make up 99% of its prey. It lives in old forests and spends the day under loose bark or in a crack in a tree. It is easy to recognise by its short, broad ears, which meet on top of the head, and its short, pug-like snout. In Georgia it has 63 records since 1879, from the sea coast up to 1900 m. Felling old trees with hollows takes away its home.
Identification
Western barbastelle: how to identify it
A small, dark bat with almost black fur frosted with whitish or golden tips. The most striking feature is the ears: short, broad, trapezoid, facing forward and joined on top of the head. The snout is short and the eyes very small, so a specialist can recognise it easily from a good photo.
Head and body 45–60 mm, tail 36–52 mm, forearm 35–43 mm, weight 5–14 g. The wingspan is 24.5–28 cm. The tail is almost as long as the body, and females are slightly larger than males.
The fur is long, silky and black-brown, with white or yellowish-golden tips that give it a frosted look. The skin and wings are dark brown to almost black. Young bats are much darker than adults.
The ears are short and broad, meet on top of the head and carry a small flap of skin on the outer edge. It never folds its ears at rest. Unlike the brown long-eared bat and its relatives, it has very small eyes.
By echolocation it is one of the easiest European bats to identify. It alternates two types of call: one at 30–37 kHz and the other at 30–43 kHz. A specialist can recognise this with an ultrasound detector, so do not catch the bat by hand.
Often confused with
The western barbastelle is a bat of old, mature forest: it needs plenty of dead and hollow trees. In summer it lives under loose bark and in cracks in trees, sometimes in rock crevices and buildings. It spends the winter in caves, mines and cellars, often in very cold places at 2–5°C. It hunts along forest edges, over water and above the tree canopy. In Georgia it has 63 records from 1879 to the present, from sea level up to about 1900 m. Many come from the Lagodekhi reserve and the Alazani floodplain forests. It has also been found in the Borjomi gorge, in Kolkheti National Park, in the Tsutskhvati, Gogoleti and Usholta caves and in the Kazreti mines. It uses underground roosts in part, mostly in winter.
The western barbastelle feeds almost only on moths. In Germany they made up 73–94% of its prey by weight, and in the Swiss Alps 99% by volume. It prefers large moths and moths that can hear bat calls. It alternates its calls at frequencies the moth cannot hear, so the moth has no time to escape. Flies, spiders and other insects are only a side dish. Such a narrow diet makes it vulnerable to declines in moths.
The western barbastelle emerges early, often before sunset. Early in the night it hunts in dark, closed places, and only later moves out into open spaces. It flies up to 20 km to hunt, about 7 km on average. It changes roosts very often, sometimes daily, so one colony needs up to 30 tree holes in a summer. Maternity colonies hold up to 30 females in trees and sometimes up to 100 in buildings. A female gives birth to one young or twins, and the young become fully independent in 6–9 weeks. Mating takes place in autumn, from September to November, at caves. During hibernation it wakes about every 15 days. It is sedentary: summer and winter roosts are usually less than 40 km apart. It lives up to 23 years.
The western barbastelle is listed as Vulnerable (VU) on the 2014 Red List of Georgia and received the same category in the 2021 national assessment. Its numbers are falling. Globally it is Near Threatened (NT, 2016), and in Europe it is Vulnerable. Across almost all of its range it is rare and declining, and it has died out in the Netherlands. The main threat is the loss of old forest: modern forestry leaves few hollow and dead trees, and young forest cannot give it enough roosts. Disturbance in caves by tourists and cavers is a threat too. In Germany, where insecticide use was reduced, its numbers have begun to recover.
Related guides
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Mostly in wooded places, from sea level up to about 1900 m. Most records come from the Lagodekhi reserve and the Alazani floodplain forests. It has also been found in the Borjomi gorge, in Kolkheti National Park and in several caves and mines. It has 63 records in all.
By its ears. They are short, broad, face forward and meet on top of the head. The snout is short and blunt, the eyes small, and the fur almost black and frosted. Do not catch the bat yourself: a photo or an echolocation recording is enough for a specialist.
Almost only moths. In some countries they make up 99% of its prey. It hunts along forest edges, over water and above the tree canopy. Because its diet is so narrow, declines in moths hurt it too.
In summer, on old trees, under loose bark and in cracks. It changes roosts almost every day, so it needs many old trees. It spends the winter in caves, mines and cellars. Felling such trees makes it disappear.
No, it is not venomous and does not attack you. But do not touch any bat with bare hands, because rabies cannot be ruled out by looks. If a bat bites or scratches you, wash the spot with soap and water for at least 15 minutes and see a doctor at once. In an emergency, call 112.
Yes. It is listed as Vulnerable (VU) on the Red List of Georgia and is Near Threatened globally (NT, 2016). Its numbers are falling almost everywhere. The main threats are the loss of old forests and hollow trees, and disturbance in caves.
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.
