I was eating breakfast this morning when I saw a fox come through the hedge and go straight to the hen coop. The chickens were safe inside, but they ran around frantically flapping, feathers flying everywhere. Of course I ran out shouting at the fox, and it looked for an exit, couldn't find one and jumped over the netting fence around the coop and up the garden. Our chickens remained nervous for some while afterwards.
We now realise this must have been what happened last Wednesday. No one had checked on the chooks all day, and when I went to have a look at them in the evening there were a lot of feathers in one corner and others scattered inside the run. I thought some feather pecking or other aggressive behaviour had taken place, which did seem out of character, but we thought they must have been bored or hungry. Now it is clear that Mr Fox (or his mate) must have shown an interest in them and put them in a blind panic.
This evening I saw the fox again, coming down the top of the garden, so I went out to scare him away.
We're wondering if we might need to invest in some electric fencing as that is meant to keep foxes out very well, although if he's around the edge of that the chickens might still panic.