A LOT more info is needed. how many acres, land type, set up for planting and flooded or just ponds and swamps, how long have the holes been established, number or wintering birds per season and as mentioned above what species of ducks frequent the holes etc. Also I know there is a huge difference in listing a property for lease vs letting family/inlaws hunt it. Duck hunting has gotten out of hand as far as prices paid for leases though so in all reality also like mentioned above with the supply/demand you could charge a lot more per acre vs a deer lease and somebody out there would be willing to pay it!