Part of my is impressed by their cleverness. The other part of me is annoyed, as now I'm wondering how I'm supposed to keep them inside????
My living room has louvre windows, and when I went back to my parents for 3 days over Xmas I kept the boys locked inside. I had a friend coming around to feed them, and knowing how badly Owen reacts to me not being there (ie. VERY badly. He won't eat if it's someone else feeding him. He came out of the cattery skin and bones), I figured it would be easier on the mind if I knew the boys were inside and not roaming the countryside looking for me. And yeah; they got sick of being inside, and worked out how to open a window.
When I got home, I had just thought that Colleen had let them outside that morning, but the next morning when I got up to go to the loo in the middle of the night, the cats started crying to go outside. I didn't let them outside, and yet when I got up properly later I couldn't find them anywhere inside, and when I opened the back door they were both there crying to be let in.
After searching the house high and low trying to find out they did it, I happened upon Marley using their escape route. The louvre's don't close all the way, so they hop up on the window sill, and get on their back legs and use their body weight to force the window open. Then, using their trusty noses, they've pushed the fly screen away from the window and get out that way. So, even when I do shut the window, there's still enough gap for them to get up and lean on it.
My stupid clever cats.