Wednesday, 24 June 2009

Bits on Bats 3: Nyctalus on Nyctalus

The Noctule is a magnificent beast. Nyctalus noctula is the biggest resident bat in Northumberland and Durham and none of the photos you'll ever find really do it justice. My first close encounter with a noctule was when one sunk its not insignificant gnashers in the flesh of my finger as I tried to fish it out of the net I'd just caught it in. I was a trainee batman at the time working up to get my own licence to catch and handle bats and dealing with your first noctule is a kind of rite of passage!

Although I have noticed quite a variation in fur colour, my first noctule, photo above, had the most gorgeous sleek ginger-brown fur. The brown long-eared bat seems to be most people's favourite - and OK I agree that it is an endearing thing - but for me the noctule does it. Enigmatic, difficult to find, sleek and little understood.

They primarily use tree holes and cavities (though I have seen a maternity roost in a chimney stack) which is why it is not easy to find their roosts. This particular bat was part of a maternity colony of about 30 breeding females that used up to 5 old woodpecker holes in different trees in a thin strip of mixed deciduous woodland flanking a small stream in south Northumberland.

I would urge you to try to get to know the noctule a little. Watch the skies in the early dusk somewhere not too far away from woodland or areas with mature trees, while the swallows and swifts are still feeding. As the light drops you might just see a noctule. A cursory glance may dismiss it as a bird but look again. They fly strongly, above tree top level, often in a purposeful straight line.

If you can get your hands on an ultrasonic bat detector and tune it to 22Khz you might just get the thrill of hearing the unique echo-location sound. There's a recording you can listen to here .
The Harry Secombe-esque raspberry (9 seconds into the recording) is a feeding buzz. As the bat closes in on a moth or beetle it increases the rate of echolocation pulses to 'see' more accurately.

While you are at it, check out the sound of the horseshoe bat too. Wouldn't we love to come across a few of those in Northumberland! Not much prospect of that without a serious dose of climate change.....

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