I have a 3.5 month white Americana pullet. She weighs about 2.5 lbs. The problem I am having, and I am not sure if it is really a serious problem, is that she seems to breathing irregularly. Her breaths are raspy, and when she exhales it sounds like a "coo". It only developed yesterday (July 3rd) during the afternoon, around 2:00 pm. At first I thought she might be overheated, since temperatures were in the high 90's and even up to 100, but the problem persisted even when temperatures dropped during the night. I make sure that their area stays cool, and even have a fan on for them. It has been 24 hrs since I first noticed, and while she is not making the irregular "coo" noise as often or as loudly, her breathing still sounds raspy. She appears to be eating and drinking well, and is still fairly active considering the heat. Her poops are normal. My other chickens that she is out with (two black Australorps, one Buff Orpington, and a Rhode Island Red/Silkie mix rooster) are not exhibiting the same behavior. I thought she might have something stuck in her throat, and that was causing her trouble breathing, or perhaps something stuck in her nose. It doesn't appear that she is just "nose-breathing" and that the noise is the whistling of nose-breathing. My chickens are kept in a well shaded 60 sq ft chicken tractor that I move often, and when I moved it this time, there were some plants that had grown up from some wild bird seed I had scattered. They have eaten the plant before and enjoy it, and no problems have come of it. I am at a loss. She doesn't appear to be distressed or sick, but this just seem normal, and it worries me. Any help is appreciated.