The lesser mouse-eared myotis (Myotis blythii) is a member of the most widely distributed groups of bats in the world, the mouse-eared or little brown bats (Myotis spp.) (3). A relatively large bat with long, narrow ears and a slender, tapering tragus(2)(3), the lesser mouse-eared myotis is blackish- or greyish-brown on the upperparts and brown-grey to off-white on the underparts, with grey tips to the hairs (2). Some individuals have a white patch between the ears (4). The wing membrane is dark and attaches at the ankles, and the tail is quite long (2).
A number of subspecies of the lesser mouse-eared myotis have been identified (2)(4)(5), but it is thought that some may represent distinct species (1)(2). The lesser mouse-eared myotis often occurs in mixed colonies with the closely related greater mouse-eared myotis (Myotis myotis), and the two can be difficult to distinguish (1)(2)(4). However, the lesser mouse-eared myotis is more slender, has a thinner snout (4), and also differs in its diet and habitat preferences (6)(7).
The diet of the lesser mouse-eared myotis consists predominantly of grass-dwelling insects, particularly bush crickets (Tettigoniidae species) (6)(9)(10). However, when bush crickets are unavailable, often between May and June, it may switch to alternative prey such as cockchafers (Melolontha melolontha) (10). The lesser mouse-eared myotis hunts by flying slowly over grass, sometimes hovering before snatching prey from grass stems or even landing briefly to pick it up (9)(10). Cockchafers may also be caught in flight or taken from leaves (10). In addition to detecting the rustling sounds made by prey, the lesser mouse-eared myotis may locate bush crickets by listening for their calls (11).
The lesser mouse-eared myotis is a gregarious species, the females congregating in large ‘maternity’ colonies to give birth. Colonies also form for hibernation(1)(3). Mating takes place around August (4), but, as in many other Myotis species, the female can store the male’s sperm over winter and fertilisation may not occur until the spring (3). The lesser mouse-eared myotis has been recorded giving birth in June, although the exact timing of births is related to food availability (12). Usually, a single young is born (2)(3), which is weaned at six to seven weeks old (2). This species has been recorded living for up to 13 years (2)(4).
The lesser mouse-eared myotis is found in southern and central Europe, North Africa, non-arid parts of south-west Asia, as far east as Kashmir, the Altai mountains and Nepal, and in scattered locations in China (1)(2)(3). It may be migratory in some areas (1)(2).
The exact limits of this species’ distribution are debated, and some studies have suggested that populations in North Africa, Malta, Sardinia and Corsica may in fact be the greater mouse-eared myotis (8).
Colonies of the lesser mouse-eared myotis are usually found in caves, mines and other underground sites, as well as in old buildings and occasionally tree holes (1)(2)(4). Foraging takes place in grassland and scrub habitats, including farmland and gardens (1), and this species appears to prefer meadows and pastures with relatively high, dense grass (7)(9)(10).
The lesser mouse-eared myotis has been recorded at elevations up to 2,100 metres in southern Spain (1)(4).
Although the lesser mouse-eared myotis is abundant in some areas, population declines have occurred in parts of its range, including in central Europe, Israel and central Asia (1). The main threats to this species come from changes in land management, including agricultural activities and the loss of traditionally cultivated meadows, as well as associated agricultural pollution (1)(9). Intensive farming can also reduce the abundance of its prey (12).
A further threat to the lesser mouse-eared myotis is disturbance at its roosts (1)(3). For example, some large colonies have disappeared in Spain as a result of disturbance by cavers, while roosts in Turkey and Syria are affected by herders who use caves for their livestock and often light fires at the entrances (1).
The lesser mouse-eared myotis is protected under a range of national and international legislation (1), including the Bonn Convention (Eurobats) (13), Bern Convention (14) and EU Habitats and Species Directive (15). Its habitats also receive some protection through the Natura 2000 network (1)(16).
In countries including Spain, Portugal and Italy, a number of lesser mouse-eared myotis colonies have been protected by the closing of cave entrances with fences. However, more colonies need protection, and alternative methods may be needed as the fences themselves can negatively affect the bats, causing direct mortality or leading to the bats abandoning the cave (1). The lesser mouse-eared myotis would also benefit from population monitoring and further action to conserve its preferred feeding habitats (1)(9), particularly where the status of this species is less secure (1).
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The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
A winter survival strategy in which an animal’s metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer.
A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
A soft cartilaginous projection extending in front of the external opening of the ear. In bats, it plays an important role in filtering returning echoes in echolocation.
Dzeverin, I.I. and Strelkov, P.P. (2008) Taxonomic status of Myotis blythii (Chiroptera, Vespertilionidae) from the Altai. Zoologichesky Zhurnal, 87(8): 973-982.
Arlettaz, R., Perrin, N. and Hausser, J. (1997) Trophic resource partitioning and competition between the two sibling bat species Myotis myotis and Myotis blythii. Journal of Animal Ecology, 66: 897-911.
Arlettaz, R. (1999) Habitat selection as a major resource partitioning mechanism between the two sympatric sibling bat species Myotis myotis and Myotis blythii. Journal of Animal Ecology, 68: 460-471.
Arlettaz, R., Ruedi, M., Ibañez, C., Palmeirim, J. and Hausser, J. (1997) A new perspective on the zoogeography of the sibling mouse-eared bat species Myotis myotis and Myotis blythii: morphological, genetical and ecological evidence. Journal of Zoology, 242: 45-62.
Güttinger, R., Lustenberger, J., Beck, A. and Weber, U. (1998) Traditionally cultivated wetland meadows as foraging habitats of the grass-gleaning lesser mouse-eared bat (Myotis blythii). Myotis, 36: 41-49.
Arlettaz, R. (1996) Feeding behaviour and foraging strategy of free-living mouse-eared bats, Myotis myotis and Myotis blythii. Animal Behaviour, 51(1): 1-11.
Jones, P.L., Page, R.A., Hartbauer, M. and Siemers, B.M. (2011) Behavioral evidence for eavesdropping on prey song in two Palearctic sibling bat species. Behavioral Ecology and Sociobiology, 65: 333-340.
Arlettaz, R., Christe, P., Lugon, A., Perrin, N. and Vogel, P. (2001) Food availability dictates the timing of parturition in insectivorous mouse-eared bats. Oikos, 95: 105-111.
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