I am interested in temps where chickens are comfortable vs what they can tolerate. What are your thoughts on temps for bantam roosters?
I can't assist. I only raise production birds, and pay no attention whatsoever to most threads on Banties, I simply don't have the time.
Thermodynamics dictates that smaller birds have greater difficulty maintaining body heat, but the differences aren't that great -
in this study of mammals (yes, not avians, so limited utility) the effects were really noted only in mammals under 100g, about 1/4#.
I therefore suspect, but honestly am only BSing my way thru, that the comfortable temperature range for bantams and full size birds are likely within a degree or two of each other. But I could be COMPLETELY WRONG.
What I do know is that larger birds, which I do have experience with, are far more susceptible to drafts which displace their feathers (impairing their natural insulation) and moisture than they are to low temperatures, and thus my focus would be there. I also know that pack creatures of all sorts, from bees and wasps thru penguins and dogs will huddle together for warmth when needed - so this is a case where having 2 or 3 likely results in a need for more warmth than a flock of 10 or 12.
And finally, I know that wind chill doesn't matter. Wind chill is a measure of *perceived* temperature on exposed skin. Ours. If a chicken is willing outside in the weather, the weather is obviously not a problem for them. If they are inside a well ventilated coop, protected from drafts, there is no wind on them to chill. So ignore the hype from the weatherman on those rare opportunities when the weather is the news. Well, maybe not ignore - you shold protect yourself when venturing out in it - but as far as your chickens are concerned, you can largely disregard anything but the thermometer.