In the old active stage the dam is wider and the pond enlarged. Tree trunks, but little overhead cover remain. The pond is somewhat channelized with open water mixed with shrubs and herbaceous ground cover. In the abandonment stage, the dam, no longer maintained, breaks and the water level decreases. Herbaceous and shrubby cover characterize this stage.
All six of the Commonwealth's common breading waterfowl were found on beaver ponds in Pennsylvania -Canada goose, wood duck, green winged teal, American black duck, hooded merganser and mallard. Overall, waterfowl used all stages of beaver ponds, but were more common on new active ponds and old active ponds. These areas produced the most broods. Wood duck, mallard and hooded merganser were the most common species seen. Geese prefer the more open older and abandoned ponds, while wood duck, hooded merganser and black duck used areas with more cover.
Beaver ponds also create habitats for marsh and song birds. The American Bittern and Virginia Rail, both secretive marsh birds, were found in older ponds. Among the wetland-dependent song birds, the Louisiana waterthrush and Acadian flycatcher were only found at active ponds, the alder flycatcher and red-winged blackbird prefer older ponds and the swamp sparrow, common yellowthroat and veery were found in all beaver pond habitats.
"A beaver pair's goal in building a dam is to create a pond where they can build a lodge, hide from predators in the water, raise offspring and store food for the winter," says Prosser. "In the process, they are creating a variety of wetland habitat for waterfowl and other wetland-dependent birds."
Editor: Ms. Prosser may be reached at 814-865-2180 or
djp137@psu.edu.
Dr.
Brooks may be reached at 814-863-1596 or '"/>
Contact: A'ndrea Elyse Messer
aem1@psu.edu
814-865-9481
Penn State
5-Aug-1998