Overview
The Brown Long-eared Bat (Plecotus auritus) is one of the most distinctive, enchanting, and anatomically remarkable vesper bats native to the ancient woodlands of Eurasia. Renowned for its enormous, translucent ears—which measure nearly the entire length of its head and body combined—this master of low-speed, hovering flight is affectionately termed the ‘whispering bat’ because of its quiet, subtle echolocation calls. It flits silently through the foliage of ancient oak, beech, and pine woods, plucking resting insects from leaves with surgical precision.
AT A GLANCE
- Common Name: Brown Long-eared Bat
- Scientific Name: Plecotus auritus
- Category: Mammals
- Subcategory: Bats
- Size: Head-and-body length 4.5 to 5.5 cm (1.8 to 2.2 in); wingspan 24 to 28 cm (9.4 to 11.0 in); ear length 3.4 to 3.9 cm (1.3 to 1.5 in)
- Weight: 6 to 12 g (0.21 to 0.42 oz)
- Lifespan: 10 to 15 years in the wild; maximum recorded age over 30 years
- Diet: Insectivore; nocturnal moths (noctuids), caterpillars, beetles, earwigs, harvestmen, and dipteran flies
- Habitat: Mature deciduous and coniferous broadleaf woodlands, parklands, orchards, and rural domestic roof spaces
- Range: Widespread across Europe and temperate Asia, from the British Isles and Scandinavia eastward to the Urals, Siberia, and Japan
- Conservation Status: Least Concern (IUCN Red List)
Ecologically, the brown long-eared bat is an essential nocturnal predator of agricultural and forest moth pests, specializing in gleaning non-flying caterpillars and earwigs directly from foliage. Its reliance on quiet bioacoustic stealth allows it to evade the tympanic defenses of deaf-moths that detect and dodge standard bat echolocation. When roosting during winter hibernation, it exhibits a charming behavioral oddity: it folds its massive ears backward beneath its wings, leaving only its pointed traguses exposed like miniature secondary ears.
Biology and Physical Characteristics
Plecotus auritus exhibits a soft, fluffy, grey-brown dorsal pelage with a warm yellowish-buff belly. Its defining anatomical feature is its pair of colossal, ribbed ears, measuring up to 39 mm in length, which are joined at their base across the forehead. These enormous acoustic funnels provide astonishing auditory sensitivity, allowing the bat to hear the faint fluttering footsteps of a moth walking across a leaf. Because it hunts largely by passive listening, it produces exceptionally faint, multi-harmonic echolocation calls (hence ‘whispering bat’) between 25 and 50 kHz, preventing tympanate moths from detecting its approach. Its broad, blunt wings and large tail membrane provide supreme aerostatic lift, allowing it to hover stationary in mid-air inside dense woodland foliage and even hover backward.
Behavior and Ecology
Brown long-eared bats emerge from diurnal roosts only in complete darkness, well after dusk, navigating low through woodland canopies. Foraging involves both aerial hawking and specialized foliage-gleaning: the bat hovers motionless beside a leaf, uses its hyper-sensitive ears to detect prey movements, and snatches the insect with its mouth or scoops it into its tail membrane. Large moths are carried to habitual ‘feeding perches’—such as open barn rafters or porch overhangs—where the bat hangs by one foot, dismembers the wings and legs, and consumes the nutritious abdomen, leaving diagnostic carpets of moth wings on the floor below. In winter, they hibernate in cold, humid caves, mines, and cellars, curling their ears tightly under their forearms to prevent delicate ear tissue from freezing.
Conservation and Human Impact
Currently assessed as Least Concern on the IUCN Red List due to expansive geographical distribution and large populations across Europe, the Brown Long-eared Bat is nevertheless strictly protected under international agreements (including the Eurobats convention). As a woodland specialist heavily dependent on old-growth tree cavities and large, uninsulated domestic roof voids, it is vulnerable to the clearance of ancient deciduous timber, artificial lighting around roosts, and modern chemical timber treatments in rural barns.
Interesting Factoid
During winter hibernation, the Brown Long-eared Bat tucks its massive ears completely backward beneath its wings to protect the delicate tissue from freezing, leaving only two small spiky inner ear flaps (traguses) visible.