We have had two pet chickens for about 3 years now, One is a rhode Is red ,and the other is an Isa brown. Both are very friendly and are wonderful pets,they both love being nursed and handled daily. There has always been an established pecking order between the two of them,with the Rhode Is being the dominant bird. Just in the last few days, the Rhode Is has become extremly aggressive toward the other hen,she will puff up the feathers and line the other hen up,and charge at her.In the past I have seen roosters behave in a similar manner, but she is definatley not a rooster. I have never seen her behave this way before. There does not seem to be any signs of brooding,and she has never been broodie before. they have both been good egg layers up until recent weeks,which I would think is more to do with their age.Although the Rhoad Is has always been the dominant bird, she has always got on extremly well with her little mate. They spend every day together in their large pen with no problems while we are at work,and are free to roam the the backyard when we come home,they normally just cruise around and hang out together ....until now. We have had to seperate the aggressive one away from other as I have a real fear she will hurt her badly (ie broken wing or neck) chasing her about in an area she can't make an effective escape. She is currently housed in our laundry overnight and during work hours,with some yard time by herself morning and afternoon. One is locked up while the other has the yard,this is not an ideal situation for either of them. We are at a lose to work out this sudden change in behaviour, also the sorts of "normal chook sounds" the Rhode Is makes are somehow different,I am sure this is somehow symptomatic of the problem. Does anybody out there have any experience with or have seen this before in their chooks. And, no..., culling/eating the offender is not an option for us,these are very loved little people and we need to sort out this weirdness soon.......Any suggestions?????