Mendips Bat Swarming Project

Group member Lewis Hillier is organising a 2021 survey using recording devices at the entrances of Mendip caves, with the hope of tracking swarming behavior of myotis species.

In a post on the SBG facebook page Lewis said:

Come and take part in the Mendips Swarming Project! We all know its been a tough time in terms of volunteering and getting hands on experience with bats, and it doesn’t look like that is about to change anytime soon. So I’ve been organising a project with Somerset Bat Group to gather some baseline acoustic data on underground sites throughout the Mendips, and I need your help. You dont need any experience, you just need to available for the key dates listed below and capable/willing to wander through woodland and go off the beaten trail! If you think you might be interested, read on and come to the Zoom session 🙂

The Mendips are littered underground sites and have been well studied for the presence of horseshoe bats. However, it’s much more difficult to survey for myotis bats because they tend to roost out of sight in crevices. There is seemingly very little data on swarming myotis at these sites, and therefore we dont know which sites are important for myotis. The plan is to deploy audiomoths at the entrances of underground sites to record acoustic data so we can compare the activity levels across all of these sites.

I’m looking for volunteers to help with the deployment/collection, and as much of the data analysis as youd like to. I’m hoping that this data will inform a future trapping project where we can gather further data on species assemblage at the sites of interest.

On the 12th August 2021 at 6pm I will be doing a Zoom session to give a more detailed introduction about the project, talk about how to use the audiomoths and discuss how it will all work. This doesn’t mean you have to help, you can just listen in and see what its all about.

– On the 21st August we will deploy the Audiomoths for the first session.
– Then the 25th September we will deploy them again for the second session.

Collection of audiomoths can happen any time after 5 days of them being in the field.

If you’re interested, please email me –

Lewis Hillier

The bat group is pleased to be able to help Lewis with the loan of our 12 AudioMoth devices.