I live in rural Turkey and usually have 15-25 chooks wandering our land (citrus farm) and beyond where it is long grass, more fruit trees etc... They all roost in trees near our dog and are fed barley in the morning, but other than that, they are left to nature. This week, one chook died, and now another seems to be following. It was quite lethargic for 2-3 days, sat down most of the time, kept away from the others and died peacefully. There was no sign of injury, mites, or other diseases; and it was almost 2 years old. Any ideas?