Heat is everyone's big bugg-bear but Sunstroke can strike at almost any time and temperature and kill a healthy vigorous chicken in as little as 300 seconds (5 minutes) Seeing that our chickens are derived from the Red. Green, and/or Grey JUNGLE fowl it continually befuddles me when people fail to provide sufficient shade for their flock. One year during a real scorcher of a heat wave I climbed into the loft of a barn standing on a piece of ground where I was growing off young game roosters to watch their reaction to Sunlight. I was never bothered having to water these youngsters because a year round, artesian spring surfaced about a quarter of a mile away and ran within 200 feet of the barn. There were a scattering of beech trees between the spring outflow and the barn. When I fed these little roosters they came from everywhere to eat and then immediately went to water. But watching from the loft of the barn not one out of the hundred or so of these chickens would venture from beneath the shade of the overhanging tree limbs to get to that water. Often they would travel 400 or more feet in a roundabout fashion to go from the shade of the barn then follow the shade of one beech tree limb to another in order to get a drink. Shade is THAT IMPORTANT to a chicken.