American Beaver Castor canadensis Kuhl, 1820    
Kingdom Animalia   >   Phylum Chordata   >   Class Mammalia   >   Order Rodentia   >   Family Castoridae   >   Genus Castor   

Status:

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.

Relationships:

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 228 records in the project database.

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An American Beaver in Harford Co., Maryland (3/3/2019). Photo by Mark Johnson. (MBP list)

Tree felled by American Beaver at Patuxent Ponds, Anne Arundel Co., Maryland (3/5/2011). Photo by Janice Browne. (MBP list)

An American Beaver dam in Montgomery Co., Maryland (1/31/2014). Photo by Bonnie Bell. (MBP list)

American Beaver lodge in Prince George's Co., Maryland (2/28/2017). Photo by Bill Harms. (MBP list)

Beaver tracks at Meadowbrook Park, Howard Co., Maryland (1/4/2014). Notes from Richard Orr: "The tracks of Beaver are distinctive since their large broad nails show well in snow. Usually however the tracks are destroyed by the dragging tail. If the tail is not dragging it is because the beaver is dragging wood -- the tail is lifted up for added balance. In this case the beaver tracks were in a snow trough and were protected from the tail or wood being dragged behind." Photo by Richard Orr. (MBP list)

An American Beaver in Prince George's Co., Maryland (11/28/2014). Photo by Dan Small. (MBP list)

An American Beaver in Howard Co., Maryland (4/15/2015). Photo by Richard Orr. (MBP list)

American Beavers in Silver Spring, Maryland (8/20/2012). Photo by Stephen Davies. (MBP list)

An American Beaver in Charles Co., Maryland (4/8/2017). Photo by William Wise. (MBP list)

An American Beaver in Silver Spring, Maryland (8/20/2012). Overall size, head shape, and especially tail shape can be used to separate from Muskrat and River Otter. Photo by Stephen Davies. (MBP list)

An American Beaver in Montgomery Co., Maryland (5/3/2016). Photo by Max Wilson. (MBP list)

A dam made by American Beaver in Dorchester Co., Maryland (4/5/2015). Photo by Jim Brighton. (MBP list)

An American Beaver in Harford Co., Maryland (4/18/2018). Photo by Josh Emm. (MBP list)

American Beaver sign in Charles Co., Maryland (1/16/2017). Photo by Bill Hubick. (MBP list)

Evidence of an American Beaver in Garrett Co., Maryland (10/6/2014). Photo by Kimberly Booth. (MBP list)

Signs of American Beaver in Garrett Co., Maryland (5/16/2015). Photo by Kimberly Booth. (MBP list)

A tree recently felled by an American Beaver in Montgomery Co., Maryland (9/25/2016). Photo by Bonnie Bell. (MBP list)

An American Beaver lodge in Montgomery Co., Maryland (9/25/2016). Photo by Bonnie Bell. (MBP list)

An American Beaver dam in Montgomery Co., Maryland (1/16/2017). Photo by Bonnie Bell. (MBP list)

An American Beaver in St. Mary's Co., Maryland (5/31/2020). Photo by Ben Springer. (MBP list)

An American Beaver lodge in Anne Arundel Co., Maryland (1/1/2020). Photo by Sue Muller. (MBP list)


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