My reference file on wood duck boxes states 4’-6’ above high water level when mounted over water. Several places recommend 10’ when over land. I’ve usually followed these and enjoyed good success. The oval hole works to keep raccoons and opossums from entering. I haven't noticed any difference in nesting usage success from the ones over water versus the ones over land.

At one of the previous Pond Boss Conferences I won a wood duck box and camera on the auction. The box is up but I never installed the camera, maybe this winter. Thanks.

Bryan