Horton (2020) describes how beavers shaped the precolonial Chesapeake Bay watershed: "For millennia, they inhabited virtually every stream of the 64,000-square-mile Bay watershed; and they controlled how the land shed water — cleanly, clearly, slowly — in a manner almost unrecognizable today.
"We understand how green the precolonial Bay watershed was; we seldom realize how wet it was....
"On the Chesapeake...rainfall did not rush to the Bay. It oozed and seeped, soaked into the ground, then reappeared, its energy dissipated through multiple flow ways.
"Sediment settled out in ponds behind dams that might occur every 50 yards on some streams. Nitrogen, the Bay’s prime pollutant today, was digested in the beaver-created wetlands and turned to harmless nitrogen gas. And the ponded landscape was lush with waterfowl and all manner of amphibians, not to mention otter and muskrat.
"...[T]hose landscapes have been gone so long that we’ve forgotten what they looked like....
[T]he trapping out of beaver — by the mid-1700s on the Chesapeake — likely was seen as beneficial.
"Some of the richest farmland was the deep bottom sediments of vanished beaver ponds."
Horton believes that beavered landscapes are more resilient to blowouts of streams.
Horton writes, "Beavers... are coming back on their own, though they are frequently trapped and killed as nuisances who chew down trees for food and dams and whose dams cause flooding. New Englanders, Canadians, several western states and even Mongolia are finding ways to peacefully coexist with all of this, having learned that the benefits of beavers far outweigh the costs.
There is evidence that watersheds can be shared with beavers using "beaver deceiver" devices "such as pipes placed in their dams to control flooding," notes Horton.
Maryland beavers almost certainly host the Beaver Parasite Beetle (Platypsyllus castoris) that is an ectoparasite that specializes on beavers throughout the U.S. and southern Canada (Evans, 2014).
There are 600 records in the project database.
| GA | AL | WA | FR | CL | MO | HO | BA | BC | HA | CE | PG | AA | CV | CH | SM | KE | QA | CN | TA | DO | WI | SO | WO |
