roosting bar refusal

Hi All. I have an Eglu cube (as well as a more traditional wooden hen house) My hens are all rescued from slaughter. None of them will roost on the wooden bars in the wooden hen house and only 1 will roost on the plastic roosting 'grid' in the Eglu. When they were in the wooden hen house they slept on the shavings on the floor under the roosting bars or in the nesting box.
My flock of 10 has dwindled to 5 so I have got them all in the Eglu now. 1 or 2 sleep in the egg laying area. 1 on the plastic grid and the other 2 on the wood shavings in the other half of the cube - I took one plastic grid out. They all seem healthy etc. The newer hens are Hubbards - heavy and not so agile - who have curly toes and I don't think they can grip on anyway. The 2 older ones are Ranger (type) and are much lighter and agile with normal toes.
If it is cold they all sit on top of each other in the egg laying area!
If I put both grids in the cube they all get on the shavings in the egg laying area. If I close off the egg laying area there is a lot of fighting!!
I guess my question is ...is this lack of roosting behaviour because they were in barns and had to sleep on the floor?
I want to get some more hens next spring and I am thinking of getting POL not ex batts - they will want roosting bars won't they? So I can put them all in the wooden hen house which has 'proper' roosting bars.
Interested to hear your thoughts or if anyone has had similar issues.

What size are the wooden bars ?

5cm x 5cm with the corners rounded off is good.

I had to put a board in front of the nest box for a while to stop them roosting there and fouling .

Most of my roosts bars are round, though never as small as a broom handle...that would be difficult for any full size chicken to roost upon.  My flock prefer the round roosts made from natural saplings/branches to the 2x4 that is also in the coop, so round vs. flat isn't truly an issue. 

Could be your roosts aren't high enough off the floor to even warrant them using them when the floor and nest boxes are more comfy.  Normally a chicken will roost on a roost due to an instinct for safety rather than the comfort of it all, but if the roosts are low or level with nesting areas, there's really no point in them mounting up to them. 

The coop may be up and the roost bars a little up from that, but the roost bars aren't even as tall as a standard chicken above the coop floor.  To a chicken, that's not any safer to roost upon than the floor, which is likely why they don't bother. 

When discussing roosts height, it's generally meant the height of the roosts above the nearest floor...to a bird, being high above where predators can walk/stand/jump is the issue.   They can't really reason that the coop is off the ground and it holds roosts inside it that make them equally far off the ground...all they can see is that the roosts aren't even a foot above the nearest solid surface where predators can be, so no point in getting up on them to sleep. 

 

Where they choose to sleep often depends on how they were raised.  If a hen roosts and she raises the chicks, they will all learn to roost.  If they are incubator hatched and raised without a hen, they usually opt for the floor, but can switch to roosting once introduced to other hens that do use the roosting bars.

Nearly every coop on the market here in the UK will feature low roosting bars.  Most of mine have always used them without any problem, but as they get older, they sometimes switch to the floor.

Old boy Foggy is my current floor sleeper.  He was always one for the roosting bars - preferably securely squished between 2 of his favourite girlies.  He's got a bit of a rheumatism in one of his legs, so I make him a nice deep layer of wood shavings in his preferred corner, which is still next to where his favourite girly roosts.  He may be old, but he's still a player