I clean the boxes each December. It's incredibly messy in the boxes with egg shells, eggs that failed to hatch, and wet wood shavings full of very tiny bugs. No self-respecting duck would nest in a box that hasn't been cleaned.
Who the heck cleans out them nests that're 50 feet up in the dead maple trees on my place? I cleaned the boxes on the ponds religiously the first three seasons...and they never used them. The insisted the dead trees on the creek over the hill were better...I gave up cleaning them out. If they want to use 'em, they can clean them on their own.
