Some coloration changes to the face, comb, & wattles probably. Instead being bright red, probably lighten to a pink since lighter colors cool. It would make sense for this function to happen with as vascular the comb, & wattles are.
Just a theory, on what it may look like.
Good point. I guess my only question with that is, what is the cutoff point? How gradual should the shift in comb colour be, and if so, at what temperature should we notice each change? Of course there are a lot more variables to this, but those are my main questions per se