Leislers Bat, Lesser Noctule

Maximum longevity: 16 years (wild)

Nyctalus leisleri is considered rare throughout its range and is protected by local laws throughout Europe. Its preferred forest habitat is patchy throughout its range. Additional lost of forests or the removal of dead trees can only reduce this species' chance of survival. Humans can help provide more habitat for Nyctalus leisleri by installing bat houses or tolerating their presence in buildings.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

Little information is available on predators of Nyctalus leisleri.

Nyctatus leisleri is a medium to small bat with a wingspan of 260 to 320 mm. Overall length is 83 to 113 mm and weight is between 11 and 20 g. The ears are low and rounded with a mushroom-shaped tragus. This species has somewhat long fur that is dark rufous brown on the back and lighter brown on the ventral side of the body. The dorsal fur is distinctly two-toned, being darker at the base. The face, ears and wing membranes are dark brown to black. The underside of the wing membranes are furred along the body and up along the arms to the fifth finger, hence the older common name 'hairy-armed bat'. The tail membrane extends to the ankles which have well-developed calcars. The tail is short and barely protrudes beyond the membrane.

Range mass: 11 to 20 g.

Range length: 83 to 113 mm.

Range wingspan: 260 to 320 mm.

Other Physical Features: endothermic ; bilateral symmetry

Little is known about the lifespan of Nyctalus leisleri. One individual is known to have lived 9 years in the wild, but other bats in the family Vespertilionidae can live several decades, so this may be a low estimate of the average lifespan.

Range lifespan
Status: wild: 9 (high) years.

Range lifespan
Status: captivity: 1 (high) years.

Average lifespan
Status: captivity: 16 years.

Leisler's bats inhabit open deciduous and coniferous forests throughout most of their range. They appear to prefer old growth forest because they requires hollow trees for roosting and hibernation. Parks and estates with ancient trees can provide appropriate habitat. However, Nyctalus leisleri can also be found in agricultural and suburban areas where it utilizes buildings and bat houses as roosting sites. It will forage over many adjacent types of habitat including fields and open water.

This species is migratory and is apparently willing to fly over inhospitable habitat, as evidenced by an individual that was found dead on a glacier at 2600 m.

Range elevation: 0 to 2600 m.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest

Other Habitat Features: suburban ; agricultural ; riparian

Nyctalus leisleri occurs throughout much of Europe and the Middle East. It ranges from the Mediterranean Sea north to Ireland, England, and central Scandinavia and from Portugal east to the Caspian Sea, western Russia and Iran. It is also known in Algeria and Libya in north Africa along the Mediterranean. Throughout its range it is relatively rare except in Ireland, where it is the third most common bat species.

Biogeographic Regions: palearctic (Native )

Nyctalus leisleri feeds primarily on small to medium-sized flying insects. It forages at heights up to 150 m, using long-distance echolocation to find prey items. Larger insects are caught individually in flight by aerial hawking. Leisler's bats are adapted for speed, not maneuverability, so they do not glean insects from stationary objects. Nyctalus leisleri is also not thought to be maneuverable enough to capture individual smaller insects. It has instead been observed to fly through swarms of such insects, probably capturing many at one time.

The specific diet of this species varies depending on local habitat. In Ireland, where forests are rare, Nyctalus leisleri forages primarily over agricultural areas. As a result, more than 20% of its diet is composed of a single species, the yellow dung-fly (Scathophaga stercoraria), which feeds on the dung of farm animals. Other important foods in pastoral areas include crane flies (Tipulidae), wood gnats (Anisopodidae) and cockchafer beetles (Scarabaeidae). Near water midges (Chironomidae) compose up to 25% of the diet. In wooded areas moths (Lepidoptera), wasps (Ichneumonidae) and lacewings (Chrysopidae and Hemerobiidae) are important prey along with a number of other insects. Non-insect invertebrates such as spiders are also sometimes eaten.

Animal Foods: insects; terrestrial non-insect arthropods

Primary Diet: carnivore (Insectivore , Eats non-insect arthropods)

Nyctalus leisleri is rare throughout its range so its role in the ecosystems it inhabits is somewhat limited. Colonies may be locally important predators of flying insects.

Nyctalus leisleri feeds on many insects that are considered pests or annoyances to humans.

Positive Impacts: controls pest population

In some parts of its range Nyctalus leisleri roosts primarily in buildings because of an absence of suitable hollow trees. This habit may annoy human inhabitats, though the species does not roost in large enough numbers to physically damage the structure.

Nyctalus leisleri communicates intraspecifically with a number of different vocalizations. Males produce a 'cheeping' call from their mating roosts or in flight to attract females. In maternity colonies, females communicate with each other and their offspring with a variety of squawks, cheeps and trills. In flight Nyctalus leisleri produces complex, songlike calls that may allow bats to identify other individuals and may be used in mate recognition or defense of foraging patches.

While in roosts chemical cues are also important and probably help females identify their offspring.

Communication Channels: acoustic ; chemical

Perception Channels: visual ; tactile ; acoustic ; ultrasound ; echolocation ; chemical

Male Nyctalus leisleri attract potential mates to breeding roosts by vocalizing and aquire harems of up to 9 females.

Mating System: polygynous

Nyctalus leisleri mates in late August or September and again in the spring. Males defend breeding roosts where they may aquire a harem of as many as 9 females. Females gather in maternity colonies where they give birth to 1 or 2 young in late spring. Only one litter is produced per year. Little is known about the specifics of development, but young can fly 30 days after birth.

Breeding interval: Nyctalus leisleri breeds twice yearly.

Breeding season: Mating occurs in the fall and again in the spring.

Range number of offspring: 1 to 2.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous

Average number of offspring: 1.5.

Female Nyctalus leisleri raise their young in maternity colonies and provide all care for the young after they are born. This includes providing milk as well as possibly transporting young between roosts.

Parental Investment: altricial ; female parental care

Bats are the only true flying mammals. In Britain they are insectivorous (eat insects), and contrary to popular misconception they are not blind; many can actually see very well (6). All British bats use echolocation to orient themselves at night; they emit bursts of sound that are of such high frequencies they are beyond the human range of hearing and are therefore called 'ultrasound' (7). They then listen to and interpret the echoes bounced back from objects, including prey, around them, allowing them to build up a 'sound-picture' of their surroundings (7). Leisler's bats produce echolocation calls of frequencies between 18-45 kHz (5). They emerge just after sunset, and with fast, high flight they hunt for moths, beetles and a range of flying insects, making frequent dives (2). Mating tends to occur towards the end of August and early September (2), but fertilisation is delayed until the following spring (6). During the mating season, a male holds a 'harem' of up to 9 breeding females in a mating roost (2). Hibernation occurs between the end of September and early April (2). The following summer, maternity roosts of 20 to 50 females form, with births occurring after mid-June (2). Leisler's bats are known to live to a maximum of 9 years (2).

In Britain, bats benefit from a very comprehensive level of legal protection (4). Under the Wildlife and Countryside Act it is illegal to intentionally kill, injure, take or sell a bat, posses a live bat or part of a bat, to intentionally (or in England and Wales, recklessly) damage, obstruct or destroy access to bat roosts. Under the Conservation Regulations it is an offence to damage or destroy breeding sites or resting places. Fines of up to £5,000 for every bat affected, and up to six months imprisonment are in place for these offences (3). Several species of bat can also benefit by bat boxes put up by the public.

This medium sized bat is similar in appearance to the noctule bat (Nyctalus noctula), but it is both darker and smaller (5). The fur is short, reddish-brown on the back and yellow-brown on the belly (2). Hairs on the back are dual coloured, being blackish-brown at the base, and reddish towards the tips (2). The wing membrane, face and ears are blackish-brown (2). Juveniles are darker in colour than adults (2).

This bat is largely a woodland species (5); maternity roosts occur in tree holes, buildings and bat boxes (2). Hibernation occurs in tree holes and cavities on and within buildings (2).

Leisler's bat occurs in England and Wales, but is absent from Scotland. In Europe, although populations are fragmented, it has a wide distribution (5), but is found mainly in the south (7). The species is fairly rare in most European countries (2) except Ireland, where it is widespread and common (7).

In Great Britain, all bats are fully protected under Schedule 5 of the Wildlife and Countryside Act (1981) as amended, and by the Conservation (Natural Habitats etc) Regulations (1994). An agreement on the Conservation of Bats in Europe (EUROBATS) under the auspices of the Bonn Convention, also known as the Convention on Migratory Species (CMS) is in force, and all European bats are listed under Appendix II of the CMS (4).

Like all bats, Leisler's bat is vulnerable to a number of threats, including the loss of roost sites; in particular hollow trees are felled if thought unsafe or 'untidy'. Habitat change and loss, affecting the availability of insect prey and causing the fragmentation of feeding habitat is a serious problem for many bats, furthermore pesticide use has devastating effects, by causing severe declines in insect prey abundance, and contaminating food with toxins that may be fatal (4).

The Leisler's bat is a rare animal for the Netherlands. For years, one was only seen every once in awhile. In 2009, the first nursing colony in 20 years was found in a hollow tree on an estate in Twente. Leisler's bats assumably migrate great distances between their summer and winter homes, some perhaps more than 800 kilometers. On Texel, an adult female was found in a shed in September 1979, on the Ploelanderweg in the woods. She died during migration and is now part of the museum collection at Naturalis in Leiden.

The lesser noctule, Leisler's bat or the Irish bat (Nyctalus leisleri), is a species of insectivorous bat belonging to the vesper bat family, Vespertilionidae. The species was named to honour the naturalist Johann Philipp Achilles Leisler