For you that have never seen a Pack Rat here you go. These little free loaders can easily fit through the 1 inch chicken wire that makes up the Duck pen and Chicken coop. But once their mouths are full of the feed meant for OUR birds no way are they fitting through the chicken wire. Reminds me of a monkey and a pickle jar, they just won't spit out all the food in their mouths to be able to escape.