Brandt’s bat, scientifically known as Myotis brandtii, is a small, elusive species. This bat, belonging to the family Vespertilionidae, is of interest due to its unique biological characteristics. It is a fascinating subject for researchers studying mammalian longevity and adaptation.
Identifying Brandt’s Bat
Brandt’s bat is a small species, weighing between 4.5 and 9.5 grams, with a forearm length ranging from 31 to 39 millimeters. Its wingspan measures between 190 and 240 millimeters. The fur on its back is light brown to reddish-brown, often with golden tips, while its underside is paler and greyish.
Distinguishing features include its short ears, which have a paler lower part and inner ear. The tragus, a small cartilaginous flap inside the ear, has a distinct notch on its edge. Its eyes are small and dark.
Habitat and Distribution
Brandt’s bat prefers forests (deciduous and coniferous woodlands) and can also be found in more open areas near water sources like lakes, rivers, and streams. This species is widely distributed across Eurasia, encompassing parts of Europe and western Asia. Its range extends through central and northern Europe, including southern Scandinavia, and reaches eastward into Russia up to the Urals.
These bats roost in sheltered, undisturbed sites, utilizing tree hollows, cracks in trunks, and behind peeling bark. They also use rock crevices and caves, and may be found in human structures such as old buildings or bat boxes. Maternity colonies comprise 20 to 60 females, though some roosts have over 200 individuals.
Diet and Behavior
Brandt’s bat feeds on small flying insects, including moths, midges, and mosquitoes. They employ echolocation to hunt, emitting high-frequency sounds that bounce off objects, allowing them to create a detailed sound map of their surroundings and pinpoint prey in flight. Their foraging behavior is characterized by agile flight patterns, hunting near water or among trees, gleaning non-flying invertebrates like spiders from foliage.
This species exhibits social behavior, forming small maternity colonies during the summer months. During winter, they hibernate in larger groups within caves, tunnels, or abandoned mines, seeking cool and humid conditions. Brandt’s bats are known for their remarkable longevity for a small mammal; while older reports of 41 years in the wild have been reclassified to the Siberian bat, true Brandt’s bats have been recorded living approximately 8.5 years in some populations and up to 18.5 years in others. This extended lifespan is partly attributed to adaptations like hibernation and a low reproductive rate, along with molecular changes in growth hormone and insulin-like growth factor 1 receptors.