Thermoregulation is the system that every warm blooded animal uses to try to keep its body temperature at an optimal level. To control the body temperature, birds can either change their heat production or influence their heat loss.

When birds are too cold, they can:
- increase their heat production by
+ consuming and burning more feed
- decrease their heat loss by
+ huddling together

When birds are too warm, they can:
- decrease their heat production by
+ eating and digesting less food
+ avoid movement, sit still
- increase their heat loss by:
+ panting, evaporating water from their beak
+ spread out their wings, to reduce isolation
+ bring more blood to the surface of the skin

Day old chicks have a very limited thermoregulation system. Their only reaction is basically by behaviour as they can not respond in a more physiolgical way. This means that when a day old chick gets cold, it can not stop it and it will get colder quickly.