USGS Home
Contact USGS
Search USGS

There are reasons to expect significant production from predator exclosures. In many instances, islands and upland sites have been highly productive for waterfowl where predators are absent and waterfowl homing characteristics come into play. Flashes of success have occurred in the electric fence world, but not sustained performance. There is much to be gained by reviewing what is known and not known about a successful exclosure.

A personal list of fence lore includes the following. Location of the fence is probably the most important factor. Fence design and construction are a close second. Competent operation and monitoring of the fence are also crucial. Practicality requires a good backup system inside the fence to remove the occasional predator that manages to penetrate it. By proper management of vegetation both inside and outside the fence, birds can be attracted inside to nest. Inside fences, nest success rates of 100% have been achieved and nest densities have reached at least 2.25 nests per acre.

There are many unknowns concerning the relationships between ducks, predators and exclosures. For example, what is brood survival after hatching? What is the homing rate for birds nesting inside the fence? How does hunting mortality influence the homing rate and productivity of the exclosure? Why have nest densities not increased greatly above 2.25 nests per acre? What is the relationship between the exclosure and predator populations? What is the most effective fence design and back-up system for a particular combination of predators?

Electric fence exclosures have been tested in a variety of locations and are featured in many plans to improve waterfowl production. As a result, stakes are high. Research to examine the unknowns should have top priority. Meanwhile those building electric fences should keep in mind that at this stage more art is involved than science.