Anyway, about this coop, the rat, the weasel, stoat and mink.
It has been suggested that a predator, should it manage to breach the coop, would be unlikely to enter for fear of violent retribution for the damage by the hens, or even our magnificent roosters.
So what's going on here then.

Is someone going to tell me I'm dealing with an intellectually challenged rat.

I mean, there's only a bit of chicken feed in the coop. It's not like she's broken into the Fort Knox of rat treats.
The reader may recall I fixed a stainless steel cage over the string that pulls the door to stop the rat from chewing through it. Looked a smart move at the time. Mrs rat thought so to. She now had a climbing frame and excellent foot purchase points to get some serious teeth pressure on one of the small round ventilation holes a had drilled.
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You may recall she chewed a hole in the right side first; the pictures are earlier in the thread. I covered that side with stainless steel mesh and there was no more damage for a while.
Then she decided to have another go. The indignation of being denied food apparently drove her to chew through the left side.
I know she's been in the coop while the chickens are in there. I've found rat droppings around the food bowl and signs of rat activity in a nest box. I wrote about that earlier.
She apparently wasn't assaulted by indignant chickens badly enough to discourage returning. It is very unusual for chickens to get off their roost bar at night to go rat hunting and their night eyesight isn't as good as the rats. It's a no contest usually. I've had rats in coops at night before. There is truth in the stories of rats chewing chicken toes off during the night.
I found this yesterday.
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That isn't where I've slipped when cutting the plastic board.

She didn't come back last night. Maybe it's a cyclic thing, maybe it's one of those bi polar problems. If I can't either kill her or get her on the appropriate meds she going to destroy the coop!
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Oh arr, about making these recycled plastic coops secure...
Being a country boy I know the weasels and stoats, probably mink as well will investigate the tunnels and openings a rat makes. It's a win win. They may either find a rat to eat or what the rat went there to eat. It's a bit of a contest with a weasel, they're considerable smaller than the mink in the video I posted. Incredible how the mink was able to squeeze through the gap under that door. A common European weasel could be almost half that girth, they could probably trot under the door holding an umbrella.
An easy rule. If there is a rat tunnel wide enough to allow the rat that dug it (this generally means an adult rat) then it's wide enough for a weasel. If that's your coop, the weasel is probably not after the chicken food.