Beavers are distributed statewide and inhabit a variety of wetlands. Today, beaver populations are on a steady increase. Trapping and available food sources are the major factors which limit beaver populations.
Beaver ponds provide a diversity of habitat types depending upon the size, age, and hydrology of the area. The ponds effect wetland quality by filtering sediment and organic matter that is normally carried down stream. The transport of organic matter provides a nutrient base for invertebrates and aquatic plants. Aquatic invertebrates are the protein base for breeding waterfowl and their broods.
Beaver ponds may be managed for waterfowl, but water level control structures need to be established. Three successful designs that have been used are the three log drain, box drain, and perforated plastic pipe. Water levels in early spring must be sufficient to attract breeding pairs and then maintained for brood rearing. However, prolonged stable water levels over several years becomes detrimental because plant diversity is lost.
Ponds should be drained after July 1st of each year. Earlier draining may expose young birds to predation. A partial draw down of 1-2 feet is recommended to promote germination of seed-producing emergent plants. The shallow areas may dry out well enough to disc and plant Japanese millet, or seed Japanese millet directly onto the moist mudflats.
In areas where elevations are not suitable for drainage, ponds may be enhanced by introducing duckweed and watermeal. If the overstory is too dense and shades out the growth of aquatic plants, clear-cutting small openings will be beneficial.
Where beaver populations are left unchecked they eventually deplete their food supply and move from the area. The beaver meadow which remains has lost plant diversity and available surface water. The site becomes useless to waterfowl and other wetland wildlife species and takes years to recover from these changes. To prevent and/or to reduce beaver damage, the population must be kept within the area’s carrying capacity. As a general rule 25-30% of the fall beaver population should be removed through trapping. Live trapping and translocating beaver is discouraged to prevent the spread of disease and because most suitable habitats are already populated with beaver.