I have 12 hens and 2 roosters, 5 hens and 1 rooster are in one pen. Of those 6 chickens, ones a Dominique Rooster, two Dominique hens, and 3 RIR hens. They are 3 years old. The rest of the chickens (7 Dominique hens, and one Dominique Rooster) are in another pen. Those are only a year old. The younger chickens were laying pretty good, getting 5-6 eggs per day from them, and about 1-2 eggs from the older ones. Now I'm only getting 1-3 eggs a day. It's been pretty hot here, highs about 90-100, and heat indexes over a 100 most days. There haven't been any major changes to them that should upset them. Any ideas on what's wrong? Is it just the heat?