Echolocation
Frequency sweeps similar to those produced by whiskered bats start at around 89 kHz ending at about 33 kHz, loudest ~45 kHz.
Clicks are slightly less regular and slower than Daubenton’s bat but heterodyne detectors cannot be relied on to identify to species. Flying in clutter they can be mistaken for pipistrelles, but their frequency range is much wider.
Habits
Brandt’s bats appear to depend on similar habitats to whiskered bats, but are more related to woodland and bodies of water. They avoid foraging in open areas such as clear cuttings and fields. In Europe they are often found at high altitudes.
Their main food items are moths and other small insects and spiders. During some seasons non-flying prey makes up a major part of their diet.
In summer they roost in trees and churches, and are regularly found in houses, particularly older ones. They have been known to use bat boxes.
Small numbers are found hibernating singly in caves and tunnels, often in tight crevices. It is uncertain where the majority of them hibernate.
Reproduction and life cycle
Mating takes places in the autumn but has also been observed in all winter months. Females can give birth in their first year but the majority do not mate until their second autumn. Nursery roosts are sometimes shared with pipistrelles and other species.
Young can fly at three weeks and by six weeks can forage by themselves. Like other Myotis species Brandt’s bats swarm in and around caves in autumn.
Brandt’s bats can have a lifespan of up to 40 years.
Distribution, status and conservation
Brandt’s bat is found throughout England and Wales and has recently been recorded in Ireland as well, but it is less common than the whiskered bat. DNA samples from a number of bats originally believed to be Brandt's bat have since been identified as Alcathoe bat. It is suggested that Brandt’s bat is a much rarer bat than previously thought.
No maternity roosts have ever been found in Kent, and there are few positive records as this species can only be identified in the hand; even then it can be difficult. However, a juvenile male was recorded on the Isle of Sheppey (Kent Bat Group), suggesting breeding, though no confirmed maternity roost yet. Two of the records shown on the map were of bats trapped in woodland during the BCT Bechstein's Bat Survey, one close to Westerham Mines during autumn swarming, and the fourth an injured bat in a garden. Some of the records shown as whiskered/Brandt’s/Alcathoe may have been Brandt’s bat.
Clearly more research is essential to find out more about this elusive species and its particular conservation needs.
