I have had opossums come to the pen and I have trapped them too. My dad said they could kill a peafowl but they might not be fast enough to catch one. I think it would be nice to have mesh netting (not chicken netting, but something zoo grade), but I don't know how expensive that would be...
We had a miniature poodle that we let into the peafowl pen. She was a good dog and was only interested in sniffing around the pen. Well my smallest peahen sneaks up to the dog and jumps on her! Since then our poodle was very afraid of the peafowl, except she did act like she wanted to eat Peep when he was a peachick. Zazouse has lots of dogs with all of her birds. I think with lots of work and maybe raising them with birds she has gotten them trained to not hurt, but look after the birds. When you free-range peafowl you have to be careful that dogs don't scare them so much that they fly away. I don't know if our new poodle is afraid of the birds or not. I know that for some reason she is really scared of big dogs. She yells very loudly when she is near a big dog as if it were trying to kill her even though the dog is not even sniffing her! Silly pup.