How can you tell if a chicken is in pain?

[Chocobo]

I originally posted this in the chick section but I think this actually the proper place.
I have gotten help with what appears to be a sick chick (original thread: https://www.backyardchickens.com/forum/viewtopic.php?id=523696) and am hopeful everything will turn out well.
But while looking in on her I had the thought that even though she looked tired she didn't appear to be in any pain. I then realized that I didn't actually know what a chicken in pain would look like except one that was peeping loudly and constantly.
In a general sense, how do chickens actually react to pain?
Do they always just peep or vocalize loudly?
If not, is there any way to tell if a chicken is in pain just by looking at it?

 

[twistedwire]

Chickens are generally always busy, unless they are sunbathing. Mine will rest in groups, by tree stumps, buried in dust, under bushes, etc.

Rarely do they do this alone.

The best indicator for pain tends to be appetite-if an animal is eating and drinking normally, it probably feels pretty good.f


If a chick is resting a lot, droopy eyes or droopy wings and no appetite, and not being busy, something isn't right.

 

[mulewagon]

Yep, like twistedwire said. Then, if they're really bad, they just stand in one place with their feathers kind of puffed out, staring ahead.

Also, if they suddenly don't want to jump on/off the roost, that can indicate a hurt leg.