heat light in the winter?

I shut them in at night in a shed that now contains about 9" of straw (added now and then since the spring). This is to protect them from predators. I don't let them out until after 9 am. They tend to lay eggs in early morning, so all their eggs are laid in the shed and I collect them every day. I don't want ducklings in the middle of winter either!

The other day it was 42F here and a couple of the ducks were bathing in the duck pond (which is a kiddie wading pool). I thought they were nuts, but they seemed perfectly happy. They also like to stand in the rain and take a bath. The only thing they seem to avoid is blowing rain. They turn their backs to it.

In the Central Valley, there is no way you need a heat lamp for them in winter.