I have searched the forum and most say 8 weeks. Mine are 2 weeks old, 3 runners. My daytime temps are 80-90 with night time temps in the upper 60s-70s. The duck house is almost totally enclosed, no drafts, with the front open. There will be a heat lamp. I feel that they will be ok, but it is my first time with ducks and am at a loss and would like you all experts to weigh in.