either of two bats of the vesper bat family, Vespertilionidae, found in Europe and North Africa (B. barbastellus) and in the Middle East and Asia (B. leucomelas). Barbastelles have short, wide ears that are joined on the forehead. Their fur is long and dark, with hairs tipped in white or gray. A barbastelle's body is about 4–6 cm (1.6–2.4 inches) long; the tail is about the same length. Weight is about 6–10 grams (0.2–0.3 ounce). Relatively heavy fliers, barbastelles live alone or in small groups and roost in trees or buildings. From fall to spring they hibernate in caves.