A lady turned up on my doorstep with a bat today. Well it makes a change from politicians and dual fuel. She found it on her patio in a Newcastle suburb. It was a) dead and b) a pipistrelle.
Bat identification is not straightforward. In flight you have little chance of accurate identification without a bat detector and a lot of practice listening to random clicks. In the hand, they are all little brown furry jobs but i/d is reasonably straightforward if you get down to small bits with fancy names.
For pipistrelle, you need all of these 3 clinchers:-
1 Size. Measure the forearm. It should be less than 38 mm.
2. The tragus. This is a little flap of cartilage at the opening of the ear. In pips it's small and round-ended rather than longer and sharper -as would be the case in the Myotis species like Whiskered, Daubenton's, Natterer's etc. To compare, look at the pip here and the whiskered bat here.
3. The presence of a post-calcarial lobe. Fiddly to find if your bat is alive and wriggling; unpleasant to find if it is dead and a tad on the wiffy side, this is a tiny flap of skin on the outside edge of the calcar - a thin stip of cartilage sticking out from the ankle that stiffens up the trailing edge of the wing membrane.
So, you 've got your dead pip in the middle of your hand. Next question - is it the Common, Soprano or even the much rarer Nathusius's Pipistrelle?
That one's for another day......