|from the February 9, 2009 Newsletter, issued from near
A BEAVER LODGE, HIGH & DRY
The other day in a swamp along the Mississippi River on the Louisiana side I visited the
beaver lodge shown below:
The lodge had been built atop a rise when the Mississippi's water was high, and now
that the water is low you can see entrances to the lodge below the pile of sticks. The
biggest entrance is in the photo's center, at the bottom. To the left of that entrance is
another smaller one. The lodge had about eight entrances, most of them mere tunnels,
unlike the big one in the center of the photo, which was more like a deep trench. I was
told that when the lodge was built water reached the lodge's base, and the entrance holes
were all underwater.
You can see a beaver dam, a diagram of a beaver tunnel, an excellent video of beavers
working, and read a lot more about them at http://animals.howstuffworks.com/mammals/beaver-dam.htm.
from the March 23, 2009 Newsletter, issued from near
A CLASSIC BEAVER DAM
Recently we looked at a beaver lodge. This week in the Refuge I ran across a classic
beaver dam, shown below:
Notice how pooled water on the high, nearer side is muddy while water below the dam
looks a bit clearer. Here the dam is fulfilling one of its services to the ecosystem by
slowing water down causing eroded soil particles suspended in the water to settle out. The
dam thus keeps eroded soil from continuing into rivers downstream. If the dam is permitted
to remain, eventually a species-rich "beaver meadow" or marsh will form above
The Beaver Dam Information Site provides loads of info about beaver dams at http://www.beaverdam.info/.
from the February 29, 2004 Newsletter, issued from near
SIGNS OF BEAVER -- OR MAYBE NUTRIA?
For the last two or three weeks, at both the Field Pond and the Forest Pond, something has
been gnawing on the stems of Black Willows along the banks. On some willows, debarked
patches a foot or more long extend up the trunks, sometimes nearly encircling them. A few
stems an inch thick or more have been completely severed as cleanly as with a sharp knife.
Several slender, two-ft-long stem segments of 10-ft-high plumegrass (genus Erianthus)
float at the water's edge as well. The willows' debarked patches and the floating
plumegrass stems are almost white, so in the rain-saturated pond area beneath overcast
skies, these signs show up like beacons. In a marshy area where grass emerges from shallow
water there's a network of runways, and the water in the runways' vicinity is cloudy.
These are all classic signs of Beaver, CASTOR CANADENSIS. Even before I moved to the Sandy
Creek area often I'd admired beaver dams at several locations in Homochitto National
Forest, which adjoins this property. Beaver are known to wander five or more miles from
their birthplaces, and 150-mile moves have been documented, so there's no reason to be
surprised to see beaver signs here.
Still, I can't say with 100% certainty that what I'm seeing is made by beaver, and not
nutria, MYOCASTOR COYPUS. I just have no experience with nutria, though in southern
Louisiana this rodent has in some places become a major problem. Nutria, nearly as large
as beaver, was introduced from Argentina into the US by people hoping to farm them for
their fur. Nutria fur never did catch on, animals escaped and were released, and now
certain wetlands are being devastated by the rapidly multiplying critters. You can read an
article entitled "Louisiana Puts Bounty on Rodents," where you meet to a fellow
who plops down more than 1,200 nutria tails and is paid $4,824 in bounty, here.
The Louisiana Department of Wildlife and Fisheries provides a fine page on the history of
nutria in our area, entitled "Nutria Population Dynamics - A Timeline," along
with illustrations of them, at www.nutria.com/site2.php.
I'm 99% sure that we have beaver visiting our ponds, not nutria. For one thing, the
highest nutria concentrations are a bit south of here. More importantly, the other day I
was standing next to a stream in the woods not far from the ponds when suddenly a splash
detonated next to me so loud that it only could have been made by a beaver who had
surfaced, seen me, then slapped his flat tail on the water before diving to his underwater
den entrance. Nutrias don't have flat tails to slap with. Also, nearby was a mammal track
in which the footprints were obliterated by something being dragged over them -- like a
Maybe someone out there can tell me how to distinguish gnawings and floating food debris
of a beaver from that of a nutria. Do nutria leave broad, flat toothmarks on debarked,
standing willow trunks, as beaver do?
from the March 2, 2009 Newsletter, issued from near
This week at St. Catherine Creek NWR wherever there were trees we saw a lot of beaver
activity. Above you see where beaver have toppled a fairly tall Black Willow onto a levee,
mostly debarked it and left behind lots of woodchips. The willow had had two trunks and if
you look at the very base of the fallen trunk you can see that the remaining stem itself
has been gnawed most of the way through and looks about to fall.
I have read that before Europeans came into North America and began killing beavers for
commerce the landscape and its ecology was much different from now because beaver had
dammed almost every stream, with the dams supporting vast communities of plants and
animals, and altering the water tables. The presence of beaver not only encouraged a level
of wildlife activity we can only imagine now, but also contributed to long term drainage
patterns, and thus the form of the landscape itself.