No heat. All most people do is screw up the birds cold tolerance by adding heat. Talking about the puffyness. This is the first time my birds have seen winter. Less than freezing here wind chill of 6* They look normal when out and about but in the coop they are poofed up. Looks like ive got more birds than I should. Tonight is the coldest they have seen. I picked a couple off the roost to see how warm their feet and legs were. Pretty toasty I must say.