Myotis nattereri (Kuhl, 1817)
Vespertilionidae

Least Concern

Description

The grey long-eared bat is a medium-sized bat, with a head and body length ranging from 44 to 51 mm, a forearm between 34 and 44 mm, and a weight typically between 7 and 10 g. The ears are long, and the snout is narrow. The fur is clearly contrasting, with a light grey or white belly and a dark grey or brownish back. The face is distinctly pink, the tragus slightly curved, and the margin of the uropatagium is covered by two rows of short bristles.

The grey long-eared bat forms a species complex (the Nattereri complex) that used to include the Escalera's bat (Myotis escalerai) and the Cryptic myotis (Myotis crypticus), now considered separate species. It is distinguished from these by the shorter bristles on the uropatagium and the attachment of the wing membrane at the base of the toe digits.

Distribution

It is found in much of Central Europe, including Great Britain and the southern part of the Scandinavian Peninsula. To the south, its distribution extends to the southern half of France, Austria, and northern Greece, reaching eastward to Turkmenistan. The exact boundaries of its distribution are not entirely clear due to the presence of different cryptic lineages.

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Roosts and phenology

Summer roosts are primarily in tree cavities and bat boxes, although solitary individuals can be found in crevices of various buildings, bridges, and other structures. Maternity colonies typically include between 20 and 50 animals in tree roosts in central Europe, although colonies of up to 120 animals have been found in buildings. In Bulgaria, maternity colonies in rock crevices usually include between 4 and 10 females. Although males can be found in maternity colonies, they often form their own colonies of up to 25 individuals. The locations of maternity colonies typically change every 2-5 days, leading to a constant fluctuation in the number of individuals. A single pup is born between early June and early July. After about 20 days, it begins its first flights, and within four weeks, the juveniles become independent.

Mating occurs in September in "swarming" roosts, where individuals from different colonies gather to mate. These "swarming" roosts can attract individuals from roosts within a radius of up to 4,100 square kilometers, with recorded movements ranging from 20 to 60 km. The species is predominantly sedentary, although some individuals undertake short migrations. Distances greater than 40 km between maternity, swarming, and hibernation roosts are rare, although occasional movements of 266-327 km are known. In winter, roosts include rock crevices, caves, mines, and subterranean rock formations, with colonies of up to 8,000 individuals having been discovered.

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Habitat and diet

This species mainly inhabits forested habitats across much of its distribution. In central and northern Europe, it is primarily found in forests, open wooded areas, as well as parks and traditional farming areas. It is also often found near bodies of water. It occurs in various types of forests, from beech and oak forests to pine forests. Its range extends from low altitudes to the tree line in mountainous regions.

Most of its prey consists of non-flying arthropods such as spiders, harvestmen, and caterpillars, though flies are also part of its diet. Beetles and moths appear in its diet seasonally. In certain areas, it also hunts millipedes, woodlice, or aquatic insects like crane flies and stoneflies. Hunting grounds are typically about 4 km from the roost. It is a species with slow and highly maneuverable flight, often hunting close to the ground and near vegetation. Most of its prey is captured directly from leaves or the ground using the uropatagium, although occasionally, it can catch prey in mid-air. Echolocation is also employed to capture animals somewhat separated from the substrate, such as spiders in webs. As a significant portion of prey is caught with the uropatagium, the bristles it possesses are believed to have a sensory function.