I just got a pair of 4 month old Ameraucanas. My 3 9 month old ladies are picking on the new girls. I’ve been keeping the new girls under the tractor in the 4x8 enclosure during the day while the older girls free range. The new girls have been here for 4 days. Do you think the new girls will run off if I let them roam or will they bond better with the older girls?  They act ok in the tractor after dark, but pick on the new kids if I turn the light on.   Inside of tractor is 4x8 and 5 ft high.
I’ve been punishing bullies by putting them in solitary at night in the downstairs run. It’s very secure, but not as cozy.
		
		
	 
	
		
	
	
		
		
			I let them roam for an hour. Every time the new girls got too close to the older girls, they were driven away. I introduced the tennis ball of justice. Any hen that picked on the little ones immediately had a tennis ball thrown at them. Even if I missed, it would break them up. My Pom-chi would retrieve the ball for an instant justice reload.
		
		
	 
Apologies to 
@Henrik Petersson for hijacking his thread.
@Flock In Texas ....Sounds like perfectly normal integration behavior, resident birds don't like new birds.
The tennis ball thing is funny, not sure how effective, but funny.
4x8 can be tight for integration, make take awhile for them to work things out inside the coop.
Here's some integration tips that might help.
Integration Basics:
It's all about territory and resources(space/food/water). 
Existing birds will almost always attack new ones to defend their resources.
Understanding chicken behaviors is essential to integrating new birds into your flock.
Confine new birds within sight but physically segregated from older/existing birds for several weeks, so they can see and get used to each other but not physically interact. 
In adjacent runs, spread scratch grains along the dividing mesh, best if mesh is just big enough for birds to stick their head thru, so they get used to eating together.
The more space, the better. Birds will peck to establish dominance, the pecked bird needs space to get away. As long as there's no copious blood drawn and/or new bird is not trapped/pinned down and beaten unmercilessly, let them work it out. Every time you interfere or remove new birds, they'll have to start the pecking order thing all over again.
Multiple feed/water stations. Dominance issues are most often carried out over sustenance, more stations lessens the frequency of that issue.
Places for the new birds to hide 'out of line of sight'(but not a dead end trap) and/or up and away from any bully birds. Roosts, pallets or boards leaned up against walls or up on concrete blocks, old chairs tables, branches, logs, stumps out in the run can 
really help. Lots of diversion and places to 'hide' instead of bare wide open run.
This used to be a better search, new format has reduced it's efficacy, but still:
Read up on integration..... BYC advanced search>titles only>
integration
This is good place to start reading, BUT some info is outdated IMO:
http://www.backyardchickens.com/a/adding-to-your-flock