Chicks with swollen vent

[docdubz]

I just went in to check on the waterer in my brooder. Decided to spend some time looking at them all to see if I could tell pullets from roos yet and I quickly noticed that a lot of the white rock roos have swollen, bald vents. Some of them have pasty butt but most of them don't, just swollen bald vents. Before today I've seen no signs of pasty butt at all.

I am brooding them outside under an ecoglow. Nighttime ambient temps are ~60. They are eating starter/grower crumble. All seem active. What would cause this? And aside from giving them a soak what should I do?

 

[Wyorp Rock]

How old are these chicks?
Are you cleaning their butts when you see them pasting up?
What do you feed?
Photo of the brooder?

 

[docdubz]

Three weeks old. Their butts are NOT pasting up, only one of them had crap on them. They are on dumor starter/grower crumble. Here's a pic of the brooder, I removed the heater because it's well into the 90s this afternoon.

 

[docdubz]

Also, they are pooping quite a lot so it's not constipation. Welp I think I just found the problem while typing this. I decided to sneak over to the brooder slowly so they wouldnt notice me and I saw one of them running around pecking at butts.

 

[Wyorp Rock]

Looks like they need more room.
Is your outside space ready for them?

 

[docdubz]

Looks like they need more room.
Is your outside space ready for them?

It is. I've just been holding out because it dips down into the mid 50s at night and I wasn't sure if they are feathered enough for that

 

[Wyorp Rock]

It is. I've just been holding out because it dips down into the mid 50s at night and I wasn't sure if they are feathered enough for that

You may need to provide supplemental heat at night for them, but if it's possible, then I would move them outside.