New hens sleeping in outside pen

I would be concerned with predators with them sleeping outside but it depends on the wildlife around you.  Is it possible to move the roost inside the coop to encourage them to sleep in there where it's a little more secure?

At some point you will lose hens that sleep outside to predators. Also, it's best for them to sleep in a dry, draft-free coop. Take a look at your coop from the hens' perspective. Are there enough roosts where the older hens don't have to be near the others? Is it comfortable? Hens can't see in the dark, so when they go in is it too dark for them to see their way to the roost? (One reason why coops should have windows!) Also, hens like to sleep high, so if the outside roosts are nice and high and you have a small coop with roosts low to the ground, they'll chose the trees. You can see my set-up on live-streaming cams at www.hencam.com. If you watch at dusk you'll see healthy, normal hen roosting behavior.

Yes, you should force them into the coop. The fenced in area is not a coop, is it?

Why force them to sleep inside?  These are chickens.  They've been sleeping in trees for a very long time.  I have a coop and outside roosts.  Their pen is completely secure and the majority of my chickens will sleep on the outside roost, even during the coldest of nights.  They are protected from rain and wind.  I tried forcing them, didn't work.  They are happy sleeping outside, I'm happy.

Years ago I learned my lesson about "secure pens." A raccoon ripped off the hawk netting to get into the pen to get into the coop (the pop door was left open) and killed my hens. Unless you have a chain link fence on sides and on top, and fencing 8 inches down, there are predators that will get in. Maybe not this year. But they will. It sounds like you have a nice coop and it's simply a matter of training them that the coop is their haven at night. Once they get it, they'll put themselves to bed at night.

My chickens love to sleep outside in the pen on their roost. I also have 3 dogs and a doggy door and a fenced in yard. The dogs will jet out the door at a drop of a hat.My chickens are safe and secure. There is always a chance of loosing a chicken for any reason. But with 3 dogs a fenced in yard and a fenced in coop I think they are as safe as they can be .My dogs are very nice to the chickens. I have a shepard that helps me hurd them in the run (mainly when a storm comes through). I know that they would protect them.