Bat research relies on being able to detect bat calls. The tricky thing about monitoring the Grey Long-eared Bat is that they are so quiet. Their very quiet echolocation and incredibly long ears has enabled them to be super-stealthy hunters – but this makes our task of monitoring them, to establish their whereabouts and measure how their populations are doing, extremely difficult.

One of our most important tools for monitoring bats is the bat detector – a device that enables us to hear the echolocation of bats, by converting these incredibly high frequency calls, into something that is within the range of human hearing.
They have come on in leaps and bounds in recent years. In the 1930’s, G.W.Pierce, a Harvard physicist developed an apparatus capable of detecting frequencies above the range of human hearing – thus the first bat detector was made.
Since then, the first UK Bat Detector Workshop was organised by the Bat Conservation Trust in 1992 and detectors have now developed into ultrasonic modules that can be plugged into a smart phone – and try to tell you which bat you are hearing! However, they still haven’t developed enough to consistently monitor Grey Long-eared Bats due to the incredibly quiet echolocation that they emit, and their habit of not echolocating at all in some situations!

Last month we had our first bat detector training session and bat walk of the season, at Devon Wildlife Trust’s nature reserve at South Efford Marsh. It was a great night for bats. Despite being cold and windy during the day, the wind dropped in the evening, enabling lots of insects to fly and resulted in lots of bat activity. We picked up 5 different bat species, but unfortunately no long-eared bats. It’s difficult to make conclusions from this. Were they there, but foraging silently over the marsh, or were they foraging elsewhere on that particular night? Either way, it was great to hear lots of bats!

If you’d like to come out to learn more about the ecology of Grey Long-eared Bats and their habitat requirements our next event will be at Trill Farm, East Devon on June 13th.
This will be an evening packed with information about this specific species, starting with a presentation, then a farm walk and later on a bat walk.
More information can be found here: or email

See you there!


Craig Dunton

Project Officer


Would you like to help this incredible species? There are numerous ways in which you can:

  • Why not volunteer for Back from the Brink? Check out our events page for opportunities near you.
  • Help us to spread the word of this species, and the others we will be helping over the next 3 years, by sharing our message across our Twitter, Facebook, Instagram and YouTube pages. Follow us: @naturebftb.
  • Finally - help support the work we do across England by donating. Our impact will be greater with your help.