Monday Mystery

Today, while Mommy was sitting at the computer, there was suddenly a loud bang on the window. We quickly looked outside but there was no one or thing around to blame. What could it have been? Mommy let me out to investigate the front yard for any strange scents but I couldn't find anything new. I discovered a few acorns in front of the window but Mommy's not so sure an acorn could fall out of the tree and hit the window. So this mystery will remain unsolved for now. But as always I am on full alert and ready to pounce anyone or anything banging on our glass.