Radio tags are go.

With the birthing period now passed (we don't like to disturb bats when they are heavily pregnant or have young attached), we're now getting stuck into our second period of radio tracking. This should hopefully give us more information about where bats go to forage at night, both within and potentially outside the woods, as well as allowing us to identify roosts used during the day time.

The first step for this part of the project was to catch some bats to tag, and so on Wednesday night we went out to trap in one of our core woodlands. Things were initially quiet, but we then caught a Bechstein's which flew into the trap as we were stood there checking it. This was shortly followed by another Bechsteins, as well as a number of lactating female Brown-long-eared bats. Both Bechstein's were good condition and were tagged before being released. The tags are very small, weighing a fraction of a gram, and are glued to skin on the bat's back between the shoulder blades. A picture of one of the tagged bats is below and, while the tag is covered by the fur glued around it, you can see the aerial which is quite long but is extremely light and flexible, so it causes minimal interference to the bat when it is flying or crawling around in the roost.

Image Copyright Stuart Blair 2011

With the tagged bats successfully released, we returned to the wood the following day to locate them in their roost. Following the signals led quickly to the discovery of both bats together in an interesting tree roost away from the main part of the wood. To maximise the information we can gather during our tracking period we decided to tag two more bats, so returned to the roost in the evening to catch bats by hand net as they emerged. Five bats were quickly caught, with well over sixty emerging in total. After examining the five bats the two most suitable were given tags and all were released.

Image Copyright Toby Thorne 2011 
(the aerial is blurred in this picture as the bat moves to take off, and so appears larger than it actually is)

We then followed the tagged bats for a few hours, to try and establish the approximate areas that they had headed to. Three appeared to be foraging in the woodland, while the forth quickly disappeared and could not be located in the immediate area.

The next couple of weeks look set to be very busy, as ideally all bats must be located during the day to identify roosts, and we must also learn as much as we can while we are able to follow the bats at tonight. We will return tonight for some more preliminary tracking, tomorrow night we are doing emergence counts from all known roosts, with the help of volunteers from the bat group, and then next week we start on some more detailed tracking of the bats.

Not sure where sleep comes into it though...