Sunday, 17 May 2009

Bats in Penkridge

A small group of us are attempting to survey the bats of Penkridge Parish this year. Not an easy job - but we have acquired a more modern Bat Detector and a Recorder which should help us with identification. What do we do? The Detector can scan from 20 Khz to 120 Khz which is the range in which all bats make their echo location calls to help them fly in the dark and home-in on insects. So we scan the airwaves and when a bat is heard calling, the detector microphone picks up the echo location calls and turns them into sounds that the human ear can hear. With the recorder we can now record the calls on a disc and when we return home, we can analyze the calls with special software on the computer which produces a sonogram. Examining the sonogram closely we are able to better identify the different species that have passed over and that we have recorded.

On a visit to Gailey Pools recently we recorded much activity over a 2 hour period after dusk. On returning home and examining the sonograms we were able to confidently say that we had recorded 4 different species of bats that evening - Common Pipistrelle, Soprano Pipistrelle, Daubenton's and Noctule bats.

We would love to hear from anyone in Penkridge who knows of good areas for bats. Pipistrelle bats are common in the built up area (I have two or three regularly feeding over my garden and house as I have trees and a pond which means lots of insects here). What we are particularly wanting to establish is where our bats roost and breed so we can produce a picture of the different species we have in Penkridge and their preferred habitats and their breeding, roosting and hibernating sites.

Bats frequently change these sites throughout the year, depending on the weather, the humidity of the sites they use and the time of their breeding. They are found in cavities (sometimes only very small) in many types of buildings, old and modern, as well as in holes in trees, under bridges, in caves, as well as in bat and bird boxes, etc.

So if you ever see bats emerging from a particular spot in a tree or in a building (perhaps from under tiles or soffit boards) at dusk, we would love to know and would pay you a visit with the detector and identify the species and try to establish how many are there. This month female bats are beginning to form maternity colonies and are looking for suitable nursery sites, such as buildings, trees or bat boxes. Male bats of most species will roost on their own or in smaller groups.

We only have 17 species of bat in the UK, all of which are protected by law because their numbers have decreased so dramatically.


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