Wednesday, 30 January 2013

Bat hibernation roost visit

Last Saturday, I met with fellow members of the Norwich Bat Group at Whitlingham to investigate 2 traditional Bat roosts in the vicinity. Even during the Winter, Bats become active every 20 days or so depending on temperature and and weather. What with the exceptionally cold weather, it was hoped that Bats would be using these tunnel roosts to keep warm, rather than the natural environment, for example trees.

The temperature was 1.5 degrees outside, and inside the first tunnel we registered around 6 degrees in the tunnel and it didn't take long until the first Bats were located. 2 Brown Long-eared, 2 Daubenten's, 1 Natt-Daub and 7+ Natterer's were found. Most were found inside purpose built Bat Bricks. Although some years ago I joined the Suffolk Bat Group in Thetford forest for a nestbox check, I have not observed these delightful creatures at such close quarters for some time. What became apparent were the similarities, and differences, between Natterer's and Daubenten's. Natterer's are larger and show a bedraggled, furry appearance. They also exhibit a pink face, compared to a more plain flesh coloured Daub.
The second tunnel was warmer at 6 degrees (the sun now stronger outside and the thaw setting in) and here we had 23 Natterer's and 5 Daubenten's, great stuff and so many were unexpected. This time, we encountered 2 Daubs hanging.
The Bats seemed on the whole unaware of our presence, but one or two began to stir (possibly a natural reflex  impossible to say) so we wasted no time in counting and leaving them in peace.

I decided it was worth a quick look for the Slavonian Grebe present on Whitlingham Great Broad, and as luck would have it the bird was showing close to the car-park and I was able to get other birders onto it.
A cracking morning, the Bats proving a fine antidote to cold Winter birding.

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