My ducklings are so big now they can just about step out of their brooder. We don't have room in our garage or shop to put them in! When my chicks were about 4 weeks old I put them outside on the patio in front of the sliding glass door with a heatlamp. It was much cooler outside then, but they did just fine. Would it be unwise to put my ducklings out at 2-3 weeks with a heat lamp? The night lows are in the mid to upper 40s. I walk out without a coat these days when I open the chicken coop so it feels pretty nice to me (yeaaa spring!).
