I actually caught it with a chick under the coop. I had waited until full dark to go get the chicks in. Since I actually saw one of my dogs kill a chick, I assumed the one that disappeared the day before was killed by her too. Now I'm thinking it was a rat since we did get back from out of town after dark. The chicks are almost a month old. I do plan to keep them inside at night anyway but when is it going to be safe for them to be out after dark? I'm going to use plaster of paris mixed with powdered sugar, but I can't be sure how well it's working so will keep the chicks in at night until they are too big to be an easy meal for the rats.