Wednesday, October 17, 2012

Busy Beavers Expand Operation

The beavers (Castor canadensis) at Audubon's Francis Beidler Forest have been busy again!  Previously, none of the beaver construction (shown in orange) could be easily seen from the boardwalk.

However, beavers have recently constructed a 20+-foot section damming the creek channel that runs under the boardwalk at #5.

The image below shows the view back toward the boardwalk (look closely).

Only a portion of this short dam can be seen from the boardwalk, but it slows water that has found its way through or under the main dam, which is another 50 meters north at the power line right-of-way/tree line interface.  A few meters behind the main dam and hidden by a thick screen of cattails, is the beaver's lodge.

Although some trees may not survive the gnawing of the beavers or the near-permanent presence of water behind the dam, other species are benefiting from the beavers' work.  As noted above, cattails are growing in a dense block from tree line to tree line in the sunny, pond-like conditions in the power line right-of-way.  A small Banded Water Snake (Nerodia fasciata fasciata) sought refuge the dam shown above and an Eastern Mud Turtle (Kinosternon subrubrum subrubrum) was foraging in the shallow water on the downstream side.  Wood Ducks (Aix sponsa) and Belted Kingfishers (Ceryle alcyon) can be heard calling behind the dam and big fish can be heard pursuing smaller prey through the deeper water.

While beavers may be providing improved habitat and a bounty for other species, they may have improved the habitat sufficiently to entice an American Alligator (Alligator mississippiensis) to take up residence in the deeper water and sunshine within the power line corridor.  If that occurs, beavers will likely become meals and the maintenance-intensive dam system will fall into disrepair.

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