Welcome to our new Colorado BYCers! I am personally biased toward bantam cochins & silkies
but I baby them....
For cold hardy birds....Alpine would sure know. We're at about 5400 ft on Front Range. Pea comb birds do well avoiding frostbite though having a well ventilated & insulated coop will go along way in caring for many breeds. I've had good luck with Easter Eggers (can be flighty from hatcheries), Speckled Sussex (real mellow & beautiful color).

For cold hardy birds....Alpine would sure know. We're at about 5400 ft on Front Range. Pea comb birds do well avoiding frostbite though having a well ventilated & insulated coop will go along way in caring for many breeds. I've had good luck with Easter Eggers (can be flighty from hatcheries), Speckled Sussex (real mellow & beautiful color).