They probably like the top of the milk crates because it's higher like another poster said AND it is flat so they can comfortably sit down over their feet.
With the roost you built, the boards are angled forcing them to have to grip it all night. Not comfy.
I built a ladder roost just like yours except I put my 1 x 4's with the flat side up (pic below) when I first put mine in the coop at 6 wks old and they didn't use it at night. They do now during the day but not at night.
Since they like to be up high, I had some left over 1/2" plywood that I put up 4 1/2 feet above a large deck storage box on shelf hangers out from the wall 4". It's 6" x 8' and they love it. They fly up to the storage box then up to the roost and stay there all night.
I think it's better to have one long roost the same height so they don't have to fight over who gets what. They still jocky around climbing over and under to get next to the chick they like for the night but then settle down.
Good luck with your chicks. Great coop and run.
With the roost you built, the boards are angled forcing them to have to grip it all night. Not comfy.
I built a ladder roost just like yours except I put my 1 x 4's with the flat side up (pic below) when I first put mine in the coop at 6 wks old and they didn't use it at night. They do now during the day but not at night.
Since they like to be up high, I had some left over 1/2" plywood that I put up 4 1/2 feet above a large deck storage box on shelf hangers out from the wall 4". It's 6" x 8' and they love it. They fly up to the storage box then up to the roost and stay there all night.
I think it's better to have one long roost the same height so they don't have to fight over who gets what. They still jocky around climbing over and under to get next to the chick they like for the night but then settle down.
Good luck with your chicks. Great coop and run.
