Ahhh.... Now that you mention it, it is the boys who look like they're struggling more than the girls, which is I think why I may have noticed it.
It is mostly the youngest birds that have their mouths open. And the last batch (5 weeks ahead of the youngest group, now about 15 weeks old or so) used to worry me with their beaks open in the shade in 80-degree weather at 9-10 weeks old. Now they are totally fine (and it's hotter). As they are in age cohorts (artificially hatched), I wonder if the older group finally "learned" the best ways to adapt and cool off. Thinking that when I get to my goal of raising chicks in a flock with older birds, then perhaps they'll learn from the older birds? Bee, that would fit your experience - you are a broody-hatch kinda person, right? (Though I agree that a healthy/strong bird will do better than a weak bird under environmental stress - I know this may sound harsh, but that's why I refuse to put out ice water, etc., until it gets REALLY hot - they need to make it in 90 degree weather without too much coddling.)
DesertChic, I'm hoping to get a naked neck on just about everything eventually...
- Ant Farm