Illinois...

[cavemanrich]

Asap we're putting a functional window on the south side. At the start of sunset I turn on a battery operated light while they get settled for the night.

When I started viewing your pix, that is the first thing that came to my mind. Then the last pix explained it all.
Your ventilation looks sufficient to me.
A note on the window. Daylight, and light into coop at dusk are very important. This way chickens see where to jump onto the roost. I think you may no longer need the battery operated light once you have the window in place. Aim for the largest window you can reasonably get to fit. During warm summer weather, that window, if open will also provide summer heat venting.
Window will also allow sunlight in winter to somewhat warm the coop interior.

 

[WhyDoILikeChickens]

I dont do much in winter. These birds are pretty tough. I might add a heat lamp below 20°. Winter before last when the windchill was -54° I locked my only hen (at that time) in her coop and after work rushed home to check on her and she looked at me like "it's ok, calm down". They run an internal temp of 104 so they run a bit warmer than us without the feathers. But this is also breed specific so research your bird temp tolerances.
Also last year I stressed over making broader temp perfect for my hens. Then one of my hens decided to hatch some eggs and I just observed her. She didn't stress. If chicks were cold they ran to warm up.
I should have worried more about raccoons than temperature. Just know your breed and watch their behavior. They have also been eating more I suppose to fluff up a bit.

 

[Molpet]

Found a big fawn with it's head stuck in the e net fence. Looks like it died last night. Pulled 50 ft of fence down. Slight damage to the fence. Thought I was going to have to get the saws all and cut her head off to get her out. Called a buddy and he was actually still around.. he's in the middle of moving. Loaded her in the tractor bucket and dumped her in his truck. He will bring steaks and roast back later in the week.

Of course I didn't think of a picture.

 

[cavemanrich]

He will bring steaks and roast back later in the week

Dat venisin shore is berrer den dat coon

 

[CommunistEgg]

The window will be as big as it can for the slanted roof! We really enjoy our big south facing window, especially in winter when it heats the whole room. This is our first year with chickens and the coop/run have been such a learning curve. I just want them to be happy in the winter like they are now

 

[cavemanrich]

Lonely Update.
At lockup the other day, Lonely scrambled to top roost.

 

[Justso]

Last year I decided to leave the window open in my hen house, no matter what the temp. I had no frostbite on anyone. I'm now a believer in a lot of ventilation.

I'm curious, you haven't had anyone climbing over the run fence? I would be out of business if I didn't have a lid on my run.

 

[Justso]

The window will be as big as it can for the slanted roof! We really enjoy our big south facing window, especially in winter when it heats the whole room. This is our first year with chickens and the coop/run have been such a learning curve. I just want them to be happy in the winter like they are now

And BTW welcome to the IL thread!

 

[CommunistEgg]

Last year I decided to leave the window open in my hen house, no matter what the temp. I had no frostbite on anyone. I'm now a believer in a lot of ventilation.

I'm curious, you haven't had anyone climbing over the run fence? I would be out of business if I didn't have a lid on my run.

At first we did, we had like 3 ft high hardware cloth and it was only occasionally! Now we have the 3 ft fencing at bottom and 3 ft on top of that of bird netting for a total fence height of 6ft. They don't ever try to get out but I think that's also because the area is large and they have everything they need in it

 

[Pawsitivly]

Hi!! I live in Western Illinois, on the border to Missouri. I have a cutie pie rooster we sadly cannot keep, and I have been given 1-2 weeks to re-home him before my parents take it into their own hands (and ‘euthanize’ him). I’m hoping I can find someone on here willing to take him!!! Here is the link with more information—>
https://www.backyardchickens.com/threads/anyone-want-a-rooster.1424047/