Rare bats (of the flying kind) on the Common?

In recent times all bats have declined in the UK and some, such as the two horseshoe bat species are now thought to be extinct in this part of the country, having declined in numbers by 99% over the last 100 years or so.  These general declines have been caused by changes in farming practices, loss of roost sites and general intolerance and have resulted in all bat species being afforded UK legal protection since 1981 and European protection since 1994.  In spite of increased protection and conservation it is taking some time for bats to recover and this is partly due to their low reproductive rate.  Although bats can live for 30 years the females only give birth to one baby each per year and of course that doesn’t mean that the young will all survive.

It can be expected that further species of bat remain to be confirmed as living or feeding in our local area with a final species list likely to be closer to 10.  Of particular interest is the possibility that two of our rarest bat species, the Barbastelle and Bechstein’s may be living locally.  These bats are rare enough to have been identified by the UK government as being in need of special conservation action plans.  They are restricted to the south of England and only a handful of maternity roosts, where females gather together to have their young, have been identified, all within the last few years.  Population estimates suggest that only a few thousand of these bats remain and records are infrequent.

Both of these rare bat species are associated with broadleaved woodland and are usually to be found roosting in the cracks and crevices of trees.  The Barbastelle is particularly associated with flaking bark, often on trees that died whilst still young, where the bat crawls under the bark to roost.  Foraging can be some distance from the roost site and I have followed bats for up to 12Km.  Bechstein’s bats tend to stay within the woodland to feed and can be found foraging along small woodland streams.

Another feature of Barbastelle and Bechstein’s preferred woodland habitat is a dense understorey.  Barbastelle bats have been found to roost in trees with a dense holly understorey and this is thought to be of particular importance during the winter.  The holly understorey is thought to act as a buffer to ambient temperature variances, producing a more stable micro-climate for roosting bats.  This can be very important for hibernating bats that prefer trees because if temperatures drop too far the bat risks frost damage to its delicate wing, tail and ear membranes.

I was impressed to see such good habitat for bats on the Common and in Pamber Forest.  The mature oak trees, streams and in particular the widespread holly understorey appeared to be very good bat habitat.  It is unusual to see such good understorey because this is often cleared for either access or aesthetic reasons. This summer I plan to do more surveys with Graham Dennis, Pamber Forest Warden, and members of the Common Working Party to find out more about bat activity in the area.

If you know of any areas where bats are particularly active or if you would like to get involved in surveys please let me know.  I would also be interested to receive any known bat roost records for buildings or trees.  If you would like any general information about bats I would be happy to advise.  Alternatively, you may like to visit the Bat Conservation Trust web site at www.bats.org.uk.

Steve Laurence
March 2006