The Natterer’s bat (Myotis nattereri) is a medium-sized species
that was often called the ‘red-armed bat’ because of its pinkish limbs. The natterer’s broad wings enables it to fly slowly so that
it can even snatch spiders from their webs.
The echolocation calls of these bats are very quiet. On a bat detector the calls are heard as irregular rapid clicks, with a sound
similar to cellophane being crumpled.
Most known summer colonies are in old stone buildings with large timber beams, such as castles, manor houses and churches, or large old timbered barns. They also roost under bridges and occasionally in the roof spaces of houses. When hibernating Natterer’s bats can be found in any small cave-like site or even exposed rock crevices. In their efforts to lodge in small crevices they can be found in almost any position, including lying on their back or sides, or even resting on their heads. Individual Natterer’s bats are occasionally found hibernating in churches, in crevices between beams.
Natterer’s have a slow to medium flight, sometimes over water, but more often amongst trees, where their broad wings and tail membrane give them great manoeuvrability at slow speed. They normally fly at heights of less than 5m, but occasionally may reach 15m in the tree canopy. Much of the prey is taken from foliage and includes many flightless or day-flying insects. Sometimes larger prey is taken to a feeding perch. They feed on flies (mainly midges), small moths, caddis flies, lacewings, beetles, small wasps, spiders.
The Natterer’s bat is a medium-sized species, distinctive by its fringe of very stiff bristles along the trailing end of its broad tail membrane. It has a bare pink face and the ears are narrow, fairly long and slightly curved backwards at the tip.. Its head and body length is 40mm - 50mm with a fur colour of light buff brown on black and a white underneath. The wingspan is 245mm - 300mm and it weighs 7g – 12g.
Mating occurs mainly in the autumn and maternity colonies of adult females are mainly formed from May-June through to July. They may change roost sites frequently. The female gives birth to a single young at the end of June or in early July. For the first 3 weeks the young bat feeds only on its mother’s milk and is left in a crèche inside the roost when its mother goes out at night to feed. During this time the juvenile may make its first flight inside the roost, and within 6 weeks it is fully weaned and able to forage for itself.
In Britain all bat species and their roosts are legally protected, by both domestic and international legislation.
Many thanks to the Bat Conservation Trust for sharing this information; for more detailed reading please visit their website below.