Created April 2008
Last updated April 2018
Nyctalus leisleri (Kuhl 1818)
Photo Chris Vine Cambridgeshire Bt Group
Up until 2007 we had no record of Leisler’s in Bedfordshire, except for a rather vague record from the 1980s and a remote recording which was either a serotine or a Leisler’s. Then in 2007 during a series of car transects, we recorded thirteen calls which we think were Leisler’s. (There is always a possibility that they were serotines.) At this stage we are unable to say whether they are resident or were just passing through.
In May 2010 we got a recording of what we have identified as a “probable Leisler” at Priory Country Park. In 2012, we got a recording of what was almost certainly a Leisler’s at Marston Thrift.
In May 2014 we managed to catch one in a harp trap near Bggleswade
They are large woodland bats with a body length of between 50 and 68mm. and weigh between 11 and 20g. The peak frequency is at 30 HZ . They are difficult to distinguish from Noctules and we may have fallen into the trap in the past of assuming that all big bats were Noctules. Since discovering serotines comparatively recently we are now looking at sonogram recordings very carefully.
Leisler’s are early emerging bats which fly high and fast but will also fly low along lanes or roads.
We have picked up several possible Leisler’s on bat detector surveys,
More information
http://www.bio.bris.ac.uk/research/bats/britishbats/index.htm
http://www.bats.org.uk/pages/uk_bat_species.html
an article on the problems of identifying Leisler’s by call alone 2011-7- Leisler’s