Myotid Bats

Natterer’s Bat (Myotis nattereri)

Natterer's Bat photo by John Altringham

Natterer’s Bat
photo by John Altringham

  • Head & body: 40 – 50 mm
  • Wingspan: 245 – 300 mm
  • Weight: 7 – 12 grams
  • Call frequency: 50 kHz (very quiet frequency range 35 – 80 kHz)
  • Age: Up to 20 years
Flight patterns:
A slow to medium flight speed anywhere between low (less than 5 metres) to tree top height and sometimes seen over water.
Emergence times:
40 minutes after sunset although show a peak at 1 hour after sunset.
Diptera (flies, midges, mosquitoes and gnats), moths, beetles, earwigs, hermiptera (true bugs) other small insects and spiders.
Feeding habitat:
Open woodland, parkland, hedgerows and, characteristically, along water side vegetation. These bats take much of their prey from foliage and include many flightless or day flying insects, falling into the category of being a gleaner.
Often crammed into crevices in stonework of man-made structures but often have a variety of roosts that are used in different ways. Commonly found in mortice joints. The size of a colony may vary between 20 to 100 bats.

Summer –
Traditionally trees but also old stone, well timbered buildings (e.g. castles and manor houses) and large timbered barns but rare in houses. Relatively few roosts are actually known. As mentioned above Natterer’s bat will use crevices in beams or gaps in beam joints, also mines and garden walls during the summer.
Winter –
Hibernation sites are used in December with most individuals leaving by March. These bats show a preference for cool entrances to caves and mines but generally any underground shelter will suffice and sometimes even exposed rock crevices or churches. Most roosts will be comprised of individual bats or small groups.
Mating occurs mainly in autumn but has been observed during the winter months. Maternity colonies of females are formed during May and June but will continue until September or October. Females give birth to a single young at the end of June or July.The young spend the first 3 weeks feeding solely on the mother’s milk and are kept in a crèche inside the roost when the mothers go out to feed. During this time the juveniles may make trial flights inside the roost to strengthen their muscles. After 6 weeks the young are fully weaned are able to forage for themselves.
General distribution notes:
Found throughout the British Isles but generally scarce and their distribution is poorly known. In Jersey, mist netting has confirmed the presence of at least one breeding colony (exhibited by capture of 2 juveniles in 2014) and the capture of at least one during a netting session in 2016.  Natterer’s is believed to be an uncommon resident in Jersey.