A small bat with shaggy fur, brown on the top and light grey with a yellowish tinge below, Brandt’s bat was only recognised as
occurring in the UK in the early 1970s because it is almost indistinguishable from the whiskered bat. Even experienced bat
workers have difficulty discriminating between the two species but Brandt’s bat tends to be larger and have a pinker face. There are also subtle differences in the teeth, the shape of the male’s penis, the length of the claws and the shape of the tragus. The bats themselves have no difficulty telling each other apart and when the two species occur in the same roost sites they will occupy separate areas.
Echolocation calls are similar to those of the whiskered bat, using frequency modulation
over a range of 32 to 89 kHz, with peak strength at about 45 kHz. The application
of sound analysis software does allow the two species to be separated with a high
degree of accuracy. Echolocation calls of both whiskered and Brandt’s bats can be confused with those of pipistrelle bats.
Brandt’s bats roost in similar sites to those favoured by whiskered bats, a cavity
roosting bat which prefers old buildings in the summer. Brandt’s bats have also been
recorded roosting in bat boxes and tree cavities. During winter hibernation caves and
tunnels are used. Brandt’s bats seem to prefer lodging themselves in small cracks,
whereas whiskered bats are often found closer to the roost entrance.
The small cylindrical droppings (6 to 9 mm long) may be found in roosts or near to the
entrances. Brandt’s bats may also be detected calling in the roost just prior to emergence.
© John Kaczanow
A crevice-roosting bat like the whiskered bat, Brandt’s bat emerges soon after sunset
and hunts throughout the night, flying beneath the canopy through woods and
around woodland edges, along hedge lines and into domestic gardens. They are less
likely to be found near water than whiskered bats. Brandt’s bats are very agile and can even pick resting insects from leaves and branches. They do seem to take more flying prey than whiskered bats. They focus on moths and smaller insects, including midges.
The breeding of Brandt’s bats has not been extensively studied, but we know that
they mate in the autumn and early winter and that the females ovulate in spring,
producing a single pup in mid summer. Although some females may be mature at
3 months, the majority do not breed until their second year. Maternity colonies are
formed in the spring and abandoned in August. Maternity roosts of 20 to 60 females
are located in buildings and sometimes trees.
Hibernating from October to March, Brandt’s bats are found in small groups, or individually, often in the cooler areas of caves. They may sometimes hibernate in groups with other species. Males may remain at the hibernation sites until late spring.
The issues that impact on whiskered bats affect Brandt’s bats as well, although the
lower population levels of the Brandt’s bat may make them more vulnerable.
Monitoring of summer maternity and hibernation roosts by licensed bat workers. Mist net trapping by licensed bat workers. Emergence surveys. Bat
detectormonitoring. Cat kills and incidental reports.
Did you know?:
The oldest bat on record was a Russian Brandt’s bat which was determined to be
41 years old.
Brandt’s bat was named in honour of the 19th century German naturalist Johann
Friedrich von Brandt.
Brandt’s bat is locally distributed in Cornwall with 0records from central and western areas, but the confusion with whiskered bats means that long term trends are difficult to determine. It occurs across England and Wales, although less commonly than the whiskered bat. Brandt’s bat occurs from western Europe across to Korea and Japan.
Brandt’s bat is regarded as being at low risk of extinction worldwide by the IUCN. In the UK it is classified as Vulnerable. The total UK population is estimated at about
30,000 individuals. To confuse matters further, another similar bat species, the alcathoe bat, has recently been identified in the UK. This European species has been
found in Yorkshire and Sussex and it is possible it may be resident in Cornwall -
watch this space…
Brandt’s bats seem to be very limited in their distribution in Cornwall and could be
one of our rarest bats, but the shortage of records may be due to their similarity to
whiskered bats. They are generally considered to be the rarer of the two species, but can only be reliably identified from roosting, or grounded, individuals so their presence may be underestimated in the county.