Older chickens prevent younger ones from entering the coop

[537264]

I put my older and younger chickens together at 2 years old and 16 weeks old. They had been in adjacent pens for 5 weeks.
The young ones run away any time the older ones come near them, although there doesn't seem to be any real pecking going on.
Evidently the older ones are not letting the younger ones into the coop at night, or they are running back out when the older ones go in? Last night one of the younger ones was squashed to death in my automatic door, on her way out. The other young ones were outside the coop.
I just added an extension to my coop so there is plenty of room for all of them.

The older ones lay in the new part, they were sleeping in that part as well when I checked on them the first few nights. The new part is at the back of the coop, well away from the door.
Any ideas on what to do? I don't have space for a second coop, I had the older ones in a tiny dog box and run until the younger ones were 16 weeks old. There are 3 older ones and now only 4 younger ones that will hopefully start laying soon.

 

[3KillerBs]

Can you turn off the auto-door for now and go out at dusk to put everyone into the coop?

 

[aart]

I just added an extension to my coop so there is plenty of room for all of them.

Pics of coop, inside and out, please?

Definitely disable the auto door until things smooth out.

 

[537264]

The coops are totally open inside and connect by a doorway. They measure 36x36 each.
The older hens roost in the left coop, the younger ones in the right coop https://photos.app.goo.gl/eWfU8yMrT34nAReW9.

 

[aart]

They measure 36x36 each.

36"?
That's pretty small for 3 and 4 birds...certainly to small for 7.
Can't see pics, please attach them here in thread.

 

[537264]

18 square feet of floor space is plenty of room for 7 chickens, considering they only sleep and lay eggs in the coops.

 

[cmom]

Can you turn off the auto-door for now and go out at dusk to put everyone into the coop?

I was wondering the same thing???
Do they have space outside of their coop to roam? The space under the coops looks a little small for 7 birds.

 

[3KillerBs]

18 square feet of floor space is plenty of room for 7 chickens, considering they only sleep and lay eggs in the coops.

The usual guidelines are that each adult, standard-sized hen needs:

4 square feet in the coop,
10 square feet in the run,
1 linear foot of roost,
1/4 of a nestbox,
and 1 square foot of permanent, 24/7/365 ventilation, which is preferably located over the birds' head when they're sitting on their roost.

18 square feet for 7 chickens is only 2.5 square feet per bird -- better than commercial caged layers, but approximately half the recommended space. Integration is one of the situations where you usually need more than the minimum space so it's not surprising that the adults are defending their scarce territory against the interlopers.

 

[aart]

18 square feet of floor space is plenty of room for 7 chickens, considering they only sleep and lay eggs in the coops.

Maybe, if they all grew up together, but integration work much better with extra space.

 

[537264]

As I said, they only sleep and lay in the coop so it is plenty of space. They have a very large fenced in run that they spend all day in. The area under the coop is a very small portion of the run. The only time any of them are ever in the coop is at night or briefly when laying.

The older ones were put into the pen/coop that the younger ones were in, not the other way around.