Long-eared bat

(Plecotus auritus)

This is the most easily recognised bat in the Europe because of its huge ears that are almost as long as it's body. At rest it is able to fold down the ears into the shape of a rams horn. When alarmed the ears slowly unfurl and the bat will scan the observer while twisting its head from side to side.

The very long ears are the giveaway for this bat but it can be very confusing when the bats are at rest and the ears are folded away out of site. The fur of Long-eared bats is brown with highlights giving it a two-tone colour. The underside is the colour of oatmeal.

Forearm 34 - 42mm / 1 inch
Length 37 - 48mm / 1 - 2 inches
Weight 6 - 12g / 3rd oz

The main roost sites for these bats are traditional built barns that have a hayloft although they can also be found in other buildings. All the roosts in my area are in barns except one which is in a 'Gentleman's Residence'. They must have free access into the roost either through window, doors or loose roof slates. Long-eared bats always roost close to their feeding area, which are usually only a few hundred yards away. They are active inside the roost from before sunset but it is well after dark that the bats emerge to feed. The place to look for Long-eared bats is along the ridge beam where they often hang in the open. Below their favourite roosts there is always an accumulation of light brown droppings and insect wings especially those of the Yellow Underwing moth. The bats like to feed in open woods and in unimproved pasture where the hover while listening for the rustles of insects.

• Emergence: late dusk, although normally only when dark. Approximately 50 - 60 minutes after sunset. Compare emergence to other N. Irish bats.

• Flight: slow and fluttering, low, can hover, very agile in confined spaces.

• Habitat: Picks insect off leaves and twigs on trees and bushes. Scans foliage in an upward direction. Occasionally gleans from grass or even the ground. Feeds in open deciduous and coniferous woodland, parkland and gardens. It does not normally forage very far away from the roost.

  Echolocation

  • Heterodyne: Long-eared bats are also called 'whispering bats' because their echolocation calls are so quiet. The bat compensates for this by having large ears that pick up more sounds. The loudest frequency to hear these bats is 40kHz but the bat has to be less than 6m away to hear the echolocations. The observer will probably see the bat before the detector kicks in. Using a heterodyne detector the echolocation of a Long-eared bat sounds like quiet clicks. Very quiet FM call. Can only be heard at a distance less than 5m from the detector. More commonly seen before it is heard. Social calls are occasionally heard as very soft 'chirps'.
  • Time expansion: Calls may contain 'missing frequencies' due to interference as a result of nasal emission. Occasionally whilst hunting in the open, uses loud low frequency FM/ CF sweeps regularly repeated. These can be heard without the use of a bat detector. The function of these calls is not clear.
  • See a time expanded call.