Survey Results 2020

The Devon Bat Survey results 2020 are in!

2020 was the 5th and final year of the Devon Bat Survey, run by Devon Greater Horseshoe Bat Project. Despite the shorter and smaller survey period due to Covid-19, 194 volunteers managed to gather over 500,000 sound files by placing specialist bat detecting equipment in 224 locations across the county.

90 of the 214 grid squares surveyed had greater horseshoe bat activity. The levels of activity varied quite a bit between locations – at one site there were 436 greater horseshoe bat passes on a single night!

In all the detectors picked just over 1000 greater horseshoe bat recordings. As part of the survey we have also recorded other bat species, providing a wealth of data to add to the Bat Conservation Trust’s National Bat Monitoring Programme, which provides vital information for effective bat conservation the UK.

Thank to everyone who took part. Your incredible efforts will help us to focus our work in key areas. It will assist both in terms of further research and targeted land management advice. Your results reports have been sent by email to you. However if you took part and haven’t received yours please email

The Survey Locations map uses tetrads to show the survey areas. Although people selected a 1km grid square to deploy their detector, the map shows a tetrad square to make it easier to view on this map. A tetrad is a 2km by 2km grid square used for biological recording.

In total the survey recorded over 500,000 sound files. Whilst we have some great technological aids for helping us to work out which are bats and which are birds, crickets and general noise, we still need to manually check lots of the files. As you can imagine, this takes a huge amount of time!

The second map shows ‘hotspots’ or the density of greater horseshoe bats recorded. This is only based on the sites surveyed. It does not mean that if an area of the map doesn’t show any greater horseshoes that they do not occur here. The strongest colours show where there were over 400 greater horseshoe passes in one location, a great result!

DBS 2020 GHB Heatmap

We have been busy mapping all the greater horseshoe, lesser horseshoe and barbastelle bat data and have created a set of cumulative maps for all years. Later this year, we hope to produce a further map showing the number of species recorded in each tetrad, so watch this space! You can view previous year’s results on our Devon Bat Survey menu.

A massive thanks to all the Monitoring Centres and volunteers who took part in this extraordinary Citizen Science survey, both in 2020 and the previous years. We couldn’t have done it without you!