Good pointIf your chicken pen is so insecure that a possum can get in, you have a big problem. It is easy to keep out possums and skunks. If either one of those can get in, a raccoon certainly can and a raccoon can wipe out the whole flock in one night. Ask my neighbor.
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I have heard that raccoons like marshmallows but skunks do not. I do not know whether this is true. I have no idea what opossums like, specifically. I do know that long ago when I first moved here, the family used to keep their trash on the back porch and one exciting night there was both a raccoon AND an opossum tearing into it. We don't keep trash there any more.