Swarming weekend with South Lancs Bat Group

Way back on August Bank Holiday weekend I joined South Lancs Bat Group for a weekend of swarming bats.  We have for several years held a project licence to trap and ring bats at two local swarming sites to find out more about the bats using the sites and hopefully add to scientific knowledge about swarming behaviour.This is not only interesting from a scientific perspective but is also a very good training opportunity – when harp trapping and mist netting at our Nathusius pipistrelle project sites, we usually catch lots of pipistrelles (fairly obviously) because we use a lure on the traps and nets specifically designed to attract Nathusius pipistrelle.  It’s not actually that common for us to catch Myotis bats on these nights.  So that means those of us who are training for a roost visitor or other type of bat licence get a lot of experience with pipistrelles but can feel less confident with Myotis species.  This is where the swarming project is great, as it’s only long-eared and Myotis bats which are in the habit of swarming (in the UK at least).

At a swarming survey we usually catch brown long-eared bats and at least two species of Myotis, if not all four of the Myotis species thought to occur in our area (Daubenton’s, Natterer’s, Brandt’s and whiskered).  So we spend a lot of time examining these bats in the hand and looking at the calcar, tragus, teeth and other ID features.  I am still working on my ID and every year at the first swarming survey spend ages re-learning how to hold the bat’s tail and feet so that I can see the calcar properly.  And don’t even ask me about the tragus shape or the tooth cusp(s) on whiskered/Brandt’s – I’m not ready for that yet.  I will get there eventually though!

The other reason attending a swarming survey is good for training purposes is that quite often the bats come thick and fast and we have to process them quickly to try and keep up with the catch rate.  It sounds counter-intuitive but having to handle, ID and process fast seems to hone skills, somehow.  There’s something about seeing 20 Daubenton’s in one night that seems to help crystallise my knowledge of how to ID this species – I only wish I didn’t have to revise this every single year 😦

I’ve asked to join in with hibernation surveys this winter, so hopefully I’ll be a *little* bit better at ID of bats in hibernation than last year.  Fingers crossed!

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