I just recently found out that squirrels have been running into the duck pen during the day while the ducks are roaming outside and eating their feed. I was wondering how it was going so quickly, and I'm mad that I've been spending money to feed squirrels instead of my ducks! I want to keep the door open so that the ducks can walk in and out and eat whenever they want, but that's seemingly impossible now unless I want to watch the pen and scare off the squirrels all day. What can I do to solve this problem? I'm afraid that this is going to be an ongoing battle for as long as I have my beloved ducks