Myotis myotis (Borkhausen, 1797)
Vespertilionidae

Least Concern

Description

A large bat species, with a head and body length between 65 and 84 mm (the largest mouse-eared bat in Europe), a tail length between 40 and 60 mm, a forearm length between 55 and 67 mm, a wingspan of 350 to 450 mm, and a weight ranging from 20 to 27 g. The ears are characteristically long, measuring between 24 and 27 mm, and the snout is particularly pronounced. The colouration is distinct between the dorsal part, which is brownish or reddish, and the ventral part, which is whitish or grayish. Generally, juveniles have a much grayer colouration than adults. The wings are gray or dark brown.

For identification purposes, the relatively large ears (with about 7-8 transverse folds), a dark spot at the tip of the tragus, and the elongated snout are important characteristics that distinguish it from the lesser mouse-eared bat (Myotis blythii). The latter typically has narrower ears (with about 5-6 transverse folds), a white spot of fur between the ears, and no dark spot on the tragus.

Distribution

It is distributed from Western Europe (Portugal) to Eastern Europe (Turkey), reaching Anatolia. The northern limit of its distribution is found south of the Netherlands, Germany, Denmark, Poland, and Ukraine. Its distribution includes the Balearic Islands and Sicily. Isolated individuals, non-residents, have been detected in the United Kingdom and southern Sweden, and it is absent in northern Africa, Corsica, Sardinia, and Malta.

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Roosts and phenology

In central Europe, breeding colonies are usually found in large spaces of abandoned buildings, attics, and occasionally under bridges and other structures, while in the Mediterranean, they primarily breed in caves. Individual males have been found in attics, towers, behind window sills, and in fissures of bridges, trees, and even in bat boxes. Reproductive colonies can be formed by thousands of individuals, usually females and their offspring, and in the Mediterranean area, they are often mixed with other species. In central Europe, breeding colonies usually comprise 50-1,000 individuals, rarely reaching 5,000, while in the Mediterranean, colonies can reach 8,000 individuals. The number of males is typically very low. Colonies form in late March or April; pups are born between May and early June, start flying at 3-4 weeks of age, and juveniles become independent at 6-8 weeks of age. Breeding roosts are abandoned once the pups are weaned, usually by late August.

In Germany, 15-40% of juvenile females mate in the first autumn and reproduce the following year, a figure that reaches 95% in Portugal. In late August, males of this species gather in caves that serve as their swarming refuges, bringing together individuals from many surrounding roosts. Mating usually occurs in male roosts. This species is not considered migratory, although movements of 50 to 100 km have been recorded between their breeding and hibernation roosts. The average movements for males is 27.5 km and for females is 51.3 km. The longest recorded movements is 436 km between the Netherlands and Germany. Hibernation roosts are typically underground and may include caves, mines, bunkers, and rock crevices, generally with high humidity and relatively high temperatures of up to 12°C. During winter, clusters of hundreds of animals can form, although smaller groups or individual bats are more common.

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Habitat and diet

Typically, it is found at altitudes below 800 meters, although in the southern part of its distribution, it can be found at higher elevations. Hunting areas are usually characterized by vegetation that allows easy access to the ground and terrestrial insects, such as mixed and deciduous forests. Population densities are often correlated with the amount of surrounding forest near the roosts. They also hunt in temporary habitats such as meadows, pastures, and recently plowed, grazed, or mowed fields. They tend to hunt within a distance of 5-15 km from the roost, with a maximum of 26 km.

The diet is dominated by terrestrial animals of 10 mm or more. The most common prey are large ground beetles (genus Carabus), followed by other terrestrial arthropods such as centipedes, spiders, and beetle larvae. Occasionally and seasonally, they also hunt smaller beetles, crickets, crane flies, and orthopterans. In the Mediterranean area, spiders can be one of the main components of the diet. This species typically hunts at low altitudes. If it locates prey based on the sound it makes, the bat approaches, flies around it for a bit, and then dives directly onto it. During this approach phase, the sense of smell likely plays an important role.