We’re Batty about BATS on Alderney.
Our Little Island loves its bats (Chiroptera in Latin). We don’t have that many types and you probably have more of them where you live, but here on Alderney we’ve grown to really appreciate these small flying mammals.
Our common species is the Common Pipestrelle. This, the smallest British bat, has a wing span of only around 22cms and a body length of just 4cms or so. Yet Pippestrelles can fly at over 25mph, as fast as the fastest human runner, and need to eat thousands of miniscule insects every night!
Perhaps the most impressive feature of the micro chiroptera (small bats), is their echolocation. This system of using sound to map the dark nocturnal world they hunt in works on the same principal as sonar for submarines and dolphins. The bats spray noise from their mouths (in the case of Pipestrelles) and listen to the thousands of echo’s that bounce back each second to calculate how far objects are away from them. You can only imagine a bat sees sound in a similar way to how we see radar used by a plane. Echolocation is vital because Bats often hunt in locations where its almost completely dark and they hunt midges and micro moths which are only millimetres in length. On the whole British bat species have good eyesight and echolocation is an additional sense which helps them hunt more effectively and they can even use it to stun the insects they are trying to catch by blasting them with incredibly strong pulses of sound.
Bat Echolocation is outside the range of human hearing (0.5-16khz), in fact Pipestrelles echolocation (45khz) is over two and a half times higher than you can hear. So to hear a bat echolocating we need bat detectors, microphones which record and replay the sound at a lower level which we can hear. Using these detectors not only can we track a bat through the night as it hunts, but hear it buzzing insects with their echolocation before they scoop them up to eat and even identify what type of bat without needing to see them.
Perhaps the reason we love our Bats so much on Alderney is that there are so few of them! Bat populations have fallen dramatically all over the world but especially in Europe, England and here in Alderney. For bats to do well they need a healthy environment which is rich in insects. These insects not only feed the bats but they help to pollinate flowers and remove rubbish, so when bat numbers drop we have to worry about what is happening the environment we live in.
So here on Alderney we celebrate our bats, be they Common Pipestrelles, or the rare Grey Long-Eared. Why don’t you see if you have a local Bat Group in your area and join them on a bat walk (http://www.bats.org.uk/pages/local_bat_groups.html)?
-Roland Gauvain, Trust Manager