My ducks are growing so fast! Even though this is my second time raising ducklings, it still blows me away! They are going to be 4 weeks old on Tuesday, and I was wondering if I could move them out into their coop with a heat lamp. They have most of their chest feathers, wing "covers" and are working on their actual wing feathers. Their backs are still pretty much fluff though I think. Will they be warm enough? Or will I have to play it by ear?