They are a species of hot coastal jungles but evolved also in bamboo cloud forests (mist forests in mountains), this is not trivial, because chickens can surviv

They are a species of hot coastal jungles but evolved also in bamboo cloud forests (mist forests in mountains), this is not trivial, because chickens can survive in cold areas and even tolerate snow, and this is required to live in most Europe and US. Without those "chill genes", chicken would never had been a successful species in Occident. Evolving in bamboo cloud forests provided the other big weapon that chickens had to conquer the planet: After many years bamboos flower, seed and die. Chicken evolved to make the most of those years of huge seed production and in those exceptional years reproduce non stop, as many times as they can, instead to lay just once as in normal years. This trait was selected later, so in a coop with plenty of food, chicken just lay, and lay, and keep laying. Enduring a wide range of temperatures, and laying more than 300 eggs a year (plus a convenient size, plus roosters fighting and singing to our amusement), made jungle red-fowl the most successful bird in the planet just by pure luck