Wednesday 17 August 2016

CCTV for bat surveying and monitoring

In my work as a wildlife photographer I have met many bat specialists and have often sympathised with the amount of antisocial night work involved in surveys. As my background is in physics and engineering, I have always found technology exciting, and have combined my interests to develop a portable CCTV system for bat roost monitoring that can reduce the need for human presence during emergence and dawn swarming surveys or bat monitoring near roosts.

 Barbastelle bats dawn swarming

The portable system I have developed works well in woodland, but can be used in buildings or caves. If mains power is present, there is even more flexibility and the possibility of obtaining HD quality videos. With power and internet availability it is even possible to view remotely.
I have used trail cameras for many years as a way of establishing the presence of wildlife, and reducing the time spent looking for it, but became frustrated with the lack of flexibility and the generally unsatisfying image quality of night videos. This led to me researching CCTV as a method of wildlife monitoring. In order to test out systems in natural environments, I joined Natural England on Dartmoor as a volunteer.
The possibility of using a CCTV system for bat monitoring was always in my mind and it became apparent that, as there was no power, internet or suitable mobile phone signal in the study area, I would have to develop a portable CCTV system that could work reliably and withstand the uncertain weather in a Dartmoor woodland.
Portable CCTV systems for wildlife are not common, except in the large expensive forms used in major projects, so I had to start from scratch. Although the basics of a CCTV system are straightforward, consisting of camera, recorder and power source, finding suitable, reliable equipment is not easy. Small details can mean the difference between success and failure, but I did eventually achieve success.
The Natural England team at Yarner Wood on Dartmoor are part of the Moor than Meets the Eye project, and I was interested to discover that, as part of the project, the Woodland Trust was carrying out research on Barbastelle bats in the Bovey Valley with a PhD student from Bristol University. Luckily the team were interested in my CCTV system and willing to allow me to test it alongside their research. In addition to the CCTV camera, an SM2 bat recorder was set up to identify the bats seen on video. One big advantage of CCTV is that only infrared light is used and there is no bat disturbance. All UK bat species and their roosts are legally protected and should never be disturbed in any way. The biggest advantage, however, is that equipment setup, data collection and analysis takes place during the day and does not involve night work.
One of the roosts being studied was a Barbastelle maternity roost which was within range of the CCTV camera without tree climbing being necessary. Unfortunately the day before the camera was to be set up at the end of July, the bats vacated the roost, and it looked like the CCTV project would fail before it started. However, as Barbastelle bats are known to switch roosts frequently, it was decided to leave the equipment set up until the end of September and hope that the bats would return.
The results were surprising and exciting and yielded a large number of interesting videos. Although the main colony did not return, throughout the period studied there were regular inspection visits to the roost, together with interesting behaviour that was not fully understood.  A large proportion of the visits did not appear to have calls associated with them at all.
In July and August, Barbastelle bats visited, but in September Long-eared bats were frequently seen on video, easily distinguished by the ears and the hovering flight:

The CCTV system performed reliably and gave some excellent quality videos.  The initial hope of an occasional video was greatly surpassed, despite there being no large colony using the tree as a day roost.
Because of the success of the pilot study, a more formal research project was proposed in order to study the call structure of Barbastelle bats in more detail. The research is taking place at present, using portable CCTV as before, together with two SM4 Wildlife Acoustics recorders. Because it is possible to see the bats as well as record their calls, one aim of the project is to measure how calls vary with activity. Another aim is to investigate if there are ‘silent’ visits. Because the roost was occupied by a Barbastelle colony for the first few weeks, there is an opportunity to study behaviour and call structure before and after roost occupation.
CCTV equipment costs less than bat recorders, the only major cost being in battery power for a portable system. I visit the site twice a week to change batteries and SD cards. This level of activity ensures that data analysis remains exciting and avoids the tedium of trawling though weeks of videos and bat calls. It also allows regular synchronisation of bat detectors and video recorder, both of which can drift in time.
Details of equipment and set up can be found in my book CCTV for Wildlife Monitoring (Pelagic Publishing). The book also give details of many other wildlife CCTV applications. For those less technically oriented I give courses for those willing to travel to Devon.
For further information:  (A new site under development)

Susan Young

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