I have several society finches together in a cage, chestnut and fawn coloured, and one that's pure white.
The problem is that the other finches are bullying the white one, they pull out her feathers and play with them. It's making her very stressed, I'm wondering why they do this...They all have enough space and seem to get along perfectly fine with each other.
I can't remove her from the cage because I have no extra cages at the moment

What else can I do?