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Wire fences were built across peninsulas using 18 gauge 1 inch mesh poultry netting. The fences were constructed to extend 5.5 feet above ground level (AGL), 1 foot below ground level and 50-150 feet into the lake. Two energized electric wires were placed on the outside of the fence, one 4 feet AGL and 1 on the top of the fence. Moats located at the base of the peninsulas were 100 yard wide and filled with water.

Peninsulas with electric barriers had 549 nests with 59% nesting success compared with 71 nests and 10% nesting success control areas. An average of 164 young hatched each year on the treated areas compared to 9 young hatched per control. Peninsulas with moats held 548 nests with 76% nesting success compared to 151 nests with 8% nesting success on control areas. An average of 773 young hatched on peninsulas with moats compared to an average of 48 young hatched on control areas. Gadwalls (Anas strepera) comprised 37% of the total nests, blue-winged teal (Anas discors) 25%, and mallards (Anas platyrhynchos) 14%.

Electric barriers plus predator management greatly benefited duck nest success but did not stop all predation. Several hens were killed by raptors and some eggs were destroyed by American crows (Corvus brachyrhynchos), mink (Mustela vison), badgers (Taxidea taxus) and raccoon (Procyon lotor).

The average cost of each fence was $5,964.96, which is an annual cost of $650.18 when amortized over 20 years. This capital cost plus yearly maintenance and predator removal expenses resulted in an annual cost of $917.93 or $5.88 for each duck hatched. The annualized cost of moats was $13,997.80 when amortized over 50 years. This figure plus annual expenses of $217.75 resulted in a $18.40 cost per duckling hatched.

These results indicate that predator barriers can be highly effective and cost efficient. The response of ducks to predator-reduced nesting environments was rapid and production was greatly enhanced even in the first year. The production capabilities of these peninsulas could rise if the nesting population increased because of homing hens or if managers increased trapping effectiveness.