I have 5 Muscovy ducklings, they're 8 weeks old. They're my first ducks. I've heard that they're hardier than chickens, so I'm wondering if I can turn off their heat lamp. At this point, their feathers are in, and I've kept their lamp on only at night. We're in NY, and it's chilly at night (20's-30's). They stay in the chicken coop at night in a rabbit hutch. Thanks.