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Plecotus auritusbrown big-eared bat

By Leah Thompson

Geographic Range

Plecotus auritus is found all across Eurasia, from Spain east to Japan, and south into India. (Roberts and Hutson, 2004; Swift, 1998)

Habitat

In general, P. auritus seem to prefer higher altitudes. In the summer, the long-eared bat can most often be found roosting in hollow trees at the edge of parks or woodlands. They are also commonly found clustering next to a chimney or along the beams of large roof spaces in stables, barns, lofts, and older buildings. From mid October to early April they hibernate in caves, mineshafts, hollow trees, under roofs, and in underground sites. Favorite roost sites of the long-eared bat can often be indicated by stains on the timbers. (Burton, 1962; Roberts and Hutson, 2004; Swift, 1998)

  • Range elevation
    1,400 (high) m
    ft

Physical Description

As their common name implies, P. auritus have large ears--almost as long as their bodies. When in flight, the bats hold the ears fully erect and extended forward. At rest, their ears fold and curl sideways in a way that resembles ram horns. During hibernation the bats fold and tuck ears down, so that only the long pointed ear cover is visible.

P. auritus have relatively large eyes without a tapetum lucidum, and slit-shaped nostrils that open laterally. They usually weigh 6-12 grams and females are slightly larger than males. They have long, silky fur that is brownish on the upper side and grayish brown below. The dental formula for the P.auritus is 2/3, 1/1, 2/3, 3/3=36.

(Grzimek, 1975; Howard, 1995; Swift, 1998)

  • Range mass
    6 to 12 g
    0.21 to 0.42 oz
  • Average mass
    8 g
    0.28 oz
  • Average basal metabolic rate
    0.082 W
    AnAge

Reproduction

These bats and mate in autumn. For males, sperm production reaches its peak in late August and September, when the testes are descended. The testes regress and sperm production ceases in November. Females delay fertilization until spring (late April or May).

Females only bear one offspring per breeding season (every year); twins are very rare. (Roberts and Hutson, 2004; Swift, 1998)

  • Breeding interval
    once per year
  • Breeding season
    Autumn
  • Range number of offspring
    1 to 3
  • Average number of offspring
    1
  • Average number of offspring
    1.33
    AnAge
  • Range gestation period
    60 to 70 days
  • Range weaning age
    40 to 45 days
  • Average weaning age
    42 days
  • Range age at sexual or reproductive maturity (female)
    12 to 15 months
  • Range age at sexual or reproductive maturity (male)
    12 to 15 months

The gestation period of Long-eared bats is relatively long, but the specifics are unknown. The young are altricial at birth, born pink and hairless with disproportionately large feet, used to grasp their mothers' fur once they are born. They feed on their mothers' milk until they are three weeks old, and then are left in the roost while the mother leaves to forage for food. At six weeks old they are weaned and able to forage for themselves. Females are often ready to breed at one year old and males are sexually mature at fifteen months.

(Roberts and Hutson, 2001; Swift, 1998)

Lifespan/Longevity

Climate is a very important factor for the survival of the young long-eared bat. Poor weather during lactation results in delayed growth, abandonment by mother and high mortality. Although records show that P. auritus are able to live up to thirty years, the average lifespan is seven years for males, sixteen years for females, and fifteen years for the sexes combined. High longevity could be due to the large amounts of time spent in a state of torpor, when the metabolic rate is very low. (Howard, 1995; Swift, 1998)

Behavior

P. auritus group together in relatively small groups (no more than 80 individuals). The only social relationship that has been identified is the mother/offspring relationship. Females remain in natal roosts their entire lives and males are likely to depart to another roost.

Long-eared bats emerge from roost after sunset and do not return again until shortly before sunrise. They hover in the confined roost briefly before emerging, displaying their ability to remain stationary in the air without any forward motion. There is no convincing evidence of migration of P. auritus, but they do hibernate from autumn to March.

(Grzimek, 1975; Swift, 1998)

Communication and Perception

Food Habits

P. auritus are insectivorous, feeding mainly on Lepidoptera (moths). They are opportunistic foragers, feeding on the most available insects, including beetles, flies, earwigs, and spiders. Long-eared bats forage in a variety of ways, such as catching insects in free flight, landing on the ground to capture prey, or hovering in mid-air to listen for movements of insects to pick them off the foliage. They forage at night, usually relatively close to their roost.

(Burton, 1962; Roberts and Hutson, 2001)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

Long-eared bats avoid most predators by only flying at night; however, they are still sometimes captured by some nocturnal predators such as owls and cats. The domestic cat is the most significant mammalian predator, especially to bats roosting under the roofs of houses. Their habit of flying close to the ground to forage and landing to catch insects makes them especially vulnerable to cats. (Roberts and Hutson, 2004; Swift, 1998)

Ecosystem Roles

P. auritus harbor relatively few parasites comparted to other bats, perhaps due to its small colony size. Several species of fleas in the family Ischnopsyllidae and mites in Spinturnicidae have been recorded on long-eared bats.

The only species of internal parasites that have been noted in P. auritus are bacteria in the genus Grahamella. (Swift, 1998)

Mutualist Species
  • Grahamella (internal parasite)
  • Ischnopsyllidae (Bat fleas)
  • Spincturnidae (Mites) including:
  • Spincturnix plecotina
  • Ornithonussus pipistrelli
  • Neomyobia plecotia
  • Leptotrombidium russicum

Economic Importance for Humans: Positive

They consume large numbers of insect pests.

  • Positive Impacts
  • controls pest population

Conservation Status

Contributors

Leah Thompson (author), University of Michigan-Ann Arbor, Kate Teeter (editor), University of Michigan-Ann Arbor.

Glossary

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Burton, M. 1962. University Dictionary of Mammals of the World. NY: Thomas Y. Crowell Company.

Grzimek, 1975. Animal Life Encyclopedia. NY: Van Nostrand Reinhold Company.

Howard, R. 1995. York, England: William Sessions Limited.

Roberts, G., A. Hutson. 2004. "The Bat Conservation Trust" (On-line). Accessed 03/23/04 at http://www.bats.org.uk/batinfo/ble.htm.

Swift, S. 1998. Long-eared Bats. London: T&AD Poyser Ltd..

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