Established healthy flock suddenly won't leave coup

[Coup de Grace]

Not sure what's going on with the chickens this morning. They always coming running out of the henhouse when I open the door. This morning, two ran out and then right back in. They are all staying inside as though afraid to come out. There are no hawks around, it's daylight so no owls present, electric fence is on to deter foxes. Egglaying is way down, 5 eggs from 17 birds the last two days. Don't know how to read this.
This is a well established flock of 18 birds ranging from 1 to 3 years old and of mixed breeds. We haven't introduced any new chickens since last spring. They have easy access to clean food and water in and out of the coup and it's not overly cold this morning.
Any ideas?

 

[silkie16]

Although you say you have electric fence on have there been any signs of foxes eg droppings or fur, if your chucks sense a fox they won't venture out

 

[redsoxs]

Did they possibly get harassed by a predator overnight - not that one got into the coop - but maybe you had a raccoon or coyote bothering them in the dark? Or did they get spooked by something sometime yesterday and now they are jittery? I recently had a stray dog in my yard - he didn't kill any birds but he chased and scared them and they stayed in the coop all the next day and laying was off for several more. That's all I can think of. It might also explain your decreased egg production. Most flocks should be on the upswing as the days are starting to get longer. Also, I noticed this is your first posting on BYC. If you would like, pop on over to the New Member Introduction Forum and say hello so the can give you a proper BYC welcome!

Here's the link: https://www.backyardchickens.com/f/44/new-member-introductions