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Why is my female rabbit going after my other 3 females rabbits they have been together for a year and she just started?

Chippy (one of the 4 females) has been going after the other 3 when around them. so now she is sepperted from them. they all live outside in a large hutch with an upstairs and down stairs(there is a door you can shut to keep them from going up stairs or down stairs so they can be seprate). chippy is now up stairs at night and down stairs during the day and gets an hour to run everyday while they other 3 are inside their hutch(there is a 6 foot run ). The 4 of them have been together for a year, since winter has started moving in, Chippy has been going after the other three by putting his head under their butt and biting them so they go away, or is it to show dominance? Today i let him sit with Cocoa (our lop ear) and he was cleaning her ears and sitting with her on top of their hutch just with her and had made Nutty (one of the other 3 rabits) go away. chippy hopped down to the run and cocoa followed and then i noticed his ear was startn to bug him a little and he made her go away (with the bighting there bottom thing). he seems to tollerate cocoa Way mor then the other 2. when ever alice (1 of the 4 chippy used to have a big bond with) comes within a foot of chippy, chippy pounced at her and alice ran off. 
I think it's dominance, will getting her spayed fix this?
I worry if chippy will be warm enough threw the Whole winter by herself...(i put warm blankets in both halves of the hutch each night for them to use and on the openings in the hutch thats made for sun to go threw we have covered so its not So cold at night)
Advice? please

i have a male rabbitt and and he is very taratorial,(i think i spelled that right)he is constintally spraying,females on the other hand can get very agressive bacause when they become sexually mature they become dominate to find the boss/top bunny.kinda like dogs.... 1 of my 5 dogs(shadow) is the top dog.and spaying is not going to change it.i read this in my vet book i am trainig really early so when i go to veteranerian school i will be caught up. so if you hane any more questions on any more animals just ask:)
Long time ago we raised a batch of rabbits. 
As the young male rabbits reached their maturity they started to bite
each others reproductive organs.

I can still hear their high pitched screams until they were separated to metal cages and sold off.