Don't know if you've tried peel and stick mineralized roof underlayment before, but we've used it on a couple of our large bird boxes, and one shed. Needs to be nailed or stapled down so it doesn't lift over time, but it's kept the wood from rotting, easy enough to hose off the droppings too
The coop and the outside brooder both have ice and water for a roof, I had extra from doing a couple roofs. I was going to do the boxes, but I ran out and I was thinking it may be too much heat with a black roof in the sun. It's already 90+ degrees out when my teal are nesting. I see other peoples boxes with it though.
I had a pair of Hoodeds in the other pen for a few years, the only issue I had was last year when my male had no mate during breeding season and he cross bread with a hen wood duck and I had 5 hybrids. I also had the Buffleheads in that pen for a couple years. I'm keeping one pen just for divers.
The hens will start to get a bulge between her legs towards her vent when she starts getting eggs. She will also start checking out the boxes. Mandarins use a Wood duck box.
