How do mice get into 2nd story windows ?

[MarShelle]

We have no trees around the house.
Mice never get into the basement.
We've only seen them on the first floor once ( they were getting in from around the air conditioner).
But, they consistently find their way into the 2nd story bedroom every time we put a fan into the window.
We never see them around the house.
Where are they living that the minute we open the upstairs window one gets in?

I'm going nuts.

[Dutch9162]

Do you have phone lines or cable wires?
Put a little talcum powder on the window ledge next time and see if you get little tracks.

[zeroflex]

Mice are excellent climbers and may very well be climbing right up the side of the house.

[smarts4god]

Mice are amazing climbers, they can run up sheer walls.

[smarts4god]

Might probably have come in through the roof - under tiles, poor lagging etc

[smarts4god]

If they've been in your loft it would be worth looking for any damage to wires