In the past, I have seen birds run, full force, into a window. Until now, I have never seen a cat run full force into a window. Ebenezer is a little bit dizzy at present. He left a spit and/or grease stain on the window. The funny thing is that the bird, about 8cm away on the other side of the window, heard the large THUD and did not budge. The birds are quickly catching on to the fact that the kitties are captive and unable to catch them…and they are sometimes a bit mean about it. One of these days, I will open the window.