Intruder in the Hen House

I am sorry to say that ‘someone’ has decided to ‘dump’ an unwanted chicken on us.  They did not ask, they just arrived at dead of night and fed their chicken in with ours.  I wish they knew how incredibly cruel that is.  Chickens do NOT take kindly to a stranger in their midst and unless introduced carefully and slowly are inclined to attack the intruder.  Ours have not, I am glad to say, attacked the new hen but they are not being kind to her and she is so scared she rarely ventures out of the house.  I hope she will not die of starvation or de-hydration, but both are possibilities.