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:
www.cctvwildlifemonitoring.co.uk (A new site under development)
Susan Young
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Any pictures of what the equipment looks like?
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