Bat night

14^th September 2011

23 adults and 11 children joined our 2011 Bat Night, including a group from Fieldtown Ladies. The evening was warm and still, a great relief after the tail end of Hurricane Katia.

John Woolliams introduced the session by explaining that bats are a large and diverse group, with about a thousand species worldwide. A bat swooped round the glade on cue, its cry converted by the bat detector into audible clicks. The call frequency of 45 kHz identified it as a common pipistrelle and John explained that these tend to work a cicuit, removing flying insects from one area before moving on, only to return later in the evening. At about 7.45 pm, it had probably just emerged and was still warming up and very hungry. It was soon joined by 2 more and John handed the detector round to see who could make the most noise by accurately following the 3 bats as they worked the glade.

There are 16 native bat species in Britain; common and soprano pipistrelles have been detected at the Community Woodland before and a brown long-eared bat has been spotted in the village. Bats use echo location to avoid obstacles and find prey, a method also used by dolphins and, more surprisingly, by shrews and mice. Children are often able to head lower frequency calls. Bats can detect distance and shape so accurately, it is thought that their brains convert the information to allow them to 'see' with their ears. Every time the bat screams, it automatically closes down its ears to avoid deafening itself, before re-opening them to receive the echo.

Bats favour a range of habitats, according to species: Daubenton's bats use a flap of skin by their tail to scoop insects from the surface of water, and Natterer's bats like open fields. Brown long-eared bats don't hunt in quite such a macho way, swooping out of the sky: they pick insects from the leaves of trees, moving in close with a whisper rather than a scream, a sound like dropping plastic straws onto a kitchen top. Bats may not breed every year and only give birth to one baby at a time in the spring, which the mothers carry with them. When the babies become too large to carry, they are left in creches, their mothers returning regularly for feeds. At this time of year, the babies are grown and bat numbers have reached a maximum.

We are grateful to John Woolliams for an interesting and enjoyable evening and, of course, to our 3 stars for their well-timed performance.

There were also Bat Nights in 2007, 2006, and 2005.

2011 news index