This medium-sized bat has incredibly long ears - 75% as long as the animal’s body and very obvious when seen flying in the
twilight. The fur is pale brown on the back, fading to cream or white beneath, although the backs of juveniles, up to a year old, may be dark grey. The face is pink or brown. The large dark ears have obvious horizontal folds and the pointed tragus is almost half as long as the outer ear. Where the ears meet on top of the head they are joined by a narrow skin flap. At rest, and when hibernating, the outer ear is folded back under the wings or curled back like a ram’s horn so that only the tragus is visible. They can weigh up to 12g and have a wingspan of 285mm. Brown long-eared bats specialise in hunting in and around trees; they are agile fliers and often pick their insect prey from the surface of leaves or branches and often land on the ground. Their echolocation calls are very quiet, beyond the capabilities of some detectors, when they can be heard they use frequencies around 50 kHz with rapid ticks. They may also rely on listening to noises of the insects themselves. After the common pipistrelle, brown long-eared bats are probably our second most common bat and are seen quite frequently as they often roost in houses and fly around gardens. The much rarer grey long-eared bat is very similar in appearance, but generally larger and darker, and it requires a detailed examination to tell them apart. There is a single, unverified, record for this species in Cornwall.
Brown long-eared bats are one of the species most likely to be seen in and around buildings. Cornwall Bat Hospital volunteers once rescued eighteen from a classroom ceiling. Elsewhere in the county they have been found roosting in a telephone box and even in a Lloyd’s Bank cash machine.
© Paul McNie
Brown long-eared bats feed in woodland, parks and gardens and are found across Cornwall, except in the most exposed situations. Their broad wings and tail allow them to fly slowly, and even hover briefly, to pick moths, caterpillars and spiders from leaves, as well as catching insects in flight.
They roost in roof spaces and barns, bat boxes and trees, and can be found in roofs at all times of the year, although they also hibernate in caves, tunnels, and trees where they tuck themselves into crevices. Brown long-eared bats are able to withstand cooler weather than many bats and hibernate rather late, emerging in March. Particularly cold hibernation sites are often chosen. They may even be seen flying on winter evenings when the temperatures rise above 4º C.
Breeding roosts are relatively small, between 20 and 30 individuals, and males are often present as well. The bats mate in the autumn, normally with partners from other colonies, and the single pups are born in June; 50 to 70% of the females breed each year, depending on the environmental conditions. Most breeding females are at least 2 years old. The pups weigh about 1.7 g at birth and are able to fly within 30 days. The oldest brown long-eared bat recorded in Europe was 30 years old.
Although the brown long-eared bat is widespread and common across much of its range, and not regarded as threatened, it is vulnerable to changing agricultural practices and loss of roosting and hibernation sites. Timber treatments and pesticide use may have direct and indirect effects on the bats and their prey. The loss of large trees, used in summer and winter, and building works carried out during the winter when brown long-eared bats may still be resident, are both considered to be detrimental.
© David Chapman
Brown long-eared bats often roost along the ridge line of roofs, leaving a characteristic trail of small, black, crumbly droppings. They may also use regular feeding perches where insect remains may be found alongside their droppings. Their habit of feeding on the ground makes them susceptible to predation by domestic cats and they are probably the bat most likely to be brought in by your pet.
Brown long-eared bats are common and widespread in Cornwall and apparently increasing, including recent reports from the Isles of Scilly (which arrived after our data collection period). In the UK and Ireland, they are found everywhere apart from the north of Scotland. They occur across western and central Europe and, together with closely related species, east towards Japan.
Did you know?:
Brown long-eared bats usually feed within 1.5 km of their roosts. Although they emerge to hunt about 30-45 minutes after dark, they are often active within the roost, and flying around, well before this.
As with all British bats the brown long-eared bat is subject to extensive legal protection in the UK and Europe. It is the UK’s second most common bat and although numbers have declined recent data in Cornwall suggest its numbers may be increasing. It is listed as a UK BAP species. This bat may also be seriously under recorded, in part because of its quiet echolocation calls.
Monitoring of summer maternity roosts and hibernation roosts by licensed bat workers. Mist net trapping by licensed bat workers. Emergence surveys. Bat detector monitoring - although of limited use for this species. Cat kills and incidental reports (brown long eared bats are the bat species most often caught by cats as the bats often land on the ground whilst hunting).