In article ,
Martin Brown writes:
On 27/09/2017 22:06, Andy Burns wrote:
Andrew Gabriel wrote:

Bats tend to fly up into corners of rooms (looking for something
they can grab hold of), and that's exactly where PIR's are often
mounted.

Maybe there's circuitry within the sensor (assuming it's not actually a
combined PIR/ultrasonic one) which happens to oscillate in the bat's
hearing range that they find "interesting" ...

I think it is more that the bat explores all the available space in the
room looking for a way out. If they ever end up on the floor then they
can find it impossible to climb up again on painted skirting boards.

In the wild they would climb the nearest rough piece of wood.

Many years ago in a previous house, I woke up in the middle of
the night. Not sure what woke me, but there was enough residual
light in the room for me to make out several things dive-bombing
me in bed. Turned the light on, and they were bats, repeatedly
swooping down in the middle of the room as they flew between
opposite corners of the room, trying but failing to find
something they could grab hold of in the corners near ceiling
level. I was thinking if I sit up, I'm going to get hit, but
then I thought they have good echo location for that, and sure
enough they went around me.

Wasn't much I could do to catch them, but they eventaully ran
out of energy and dropped to the floor. Hadn't occured to me
they can't take off from the floor, but I lifted the outside
at that point and put them in a tree.

They had come in where some large holes were left in the ceiling
through to the loft the previous day. I fixed up the holes
next day. I was often in that loft and it was all nice and clean
with new insulation, and I never saw any sign of them in the
loft, but presumably they were there somewhere.

--
Andrew Gabriel
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