Secrets of a bat survey!

This past weekend I was invited on my first ever bat box survey! And let me tell you I may now have a new love for bats. So, today’s post I thought I would retell the survey day, and discuss what actually went on; as well as addressing a few misconceptions I had about bats/surveying!

Small note:

This survey was conducted by/with trained and licensed individuals; UK bat species are protected under law, and it is an offence to go around disturbing them without appropriate training. I was very lucky to be invited along and feel privileged that I got to see what was involved in a survey! When speaking to the experts it became apparent that they also open some checks up to members of the public to see what is involved, if you would like to do this, I suggest checking local nature reserve and bat group event pages. Also, during Saturday’s survey no bats where ever handled or moved but in surveys where this does occur only licenced individuals can hold them and everyone has to wear PPE; even with the PPE those holding bats must also have had a rabies vaccine to avoid any potential risk.

The Survey:

Firstly, lets address the time of day… I thought that all bat surveys took place at night because that’s when bats are actually active. However it turns out that bat box surveys actually take place during the day (and in my case a 9am on a rather sunny Saturday!). Now when reviewing this I actually realised this made a lot of sense because if bats are flapping around at night, then there would be nothing in the boxes to check (duh!). Secondly, how do you actually check a box? Like those things are pretty high up in the trees- its not like a dormouse box where they are all placed at arm level? Well, the answer lies in two different methods: 1. Ladder (physically climbing up, opening a box, and looking for bats). 2. Endoscope camera/torches and binos.

The method we used on Saturday was number two, mainly because you need at least six people to carry a ladder around the forest! Also, upon speaking to the bat experts (licenced bat checkers) it was clear that a lot of the time even with the ladder they would still use the endoscope camera and binoculars first because you don’t want to blindly go opening boxes or disturbing maternity roosts.

So, let me tell you about the coolest bit of ecology equipment I have seen- an endoscopic camera! Now if you are unfamiliar with endoscopic cameras, it is basically a tiny camera with a light on the end of a piece of wire most commonly used (that I can think of) in hospitals when they want to see what’s going on inside your body. In the case of bat surveys, the endoscope is stuck on an extending pole in order to reach the boxes.

Now on this particular survey there was two types of boxes- one which was completely enclosed with only a small entrance and another which looked more like a large bird box without a floor and separated sections. The second of these could be checked by just using clever torch aim and binoculars. These boxes were all located on trees in small clusters of about three boxes per tree/area.

Actually, surveying the bats: Checking bat boxes is very similar to checking dormice boxes, in that you can never be sure what you will find in the box- it could be completely empty or contain anything from bats, birds or even bugs. This can make the task of checking the boxes both really exciting and boring at the same time because you could go all day and not see a single bat or see a bat in every box, you just never know!

On the survey I attended there was around 60 boxes to check, placed in groups of three or so boxes to a tree; and we found bats in around 10-15 of the boxes all together. Over the course of the survey, the bats we did find where not all of the same species and differed in how many in each box- this was due to some of the boxes being known maternity roosts! I was quite surprised at how many bats could fit into a single box, with upwards of 15 individuals squished into one!

Overall, the survey made for a very exciting Saturday, and to be able to see the individual bats so up close with the equipment was a great experience and the even better news is I was invited to attend next months survey as well! So, expect to catch up with some more bats in the future. I hope you found this post insightful, and it gave you an idea about what goes on during a bat survey!