permaculture

["Lawrence F. London, Jr." <lfl@intrex.net>]

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Subject: [IWM-L] Beavers helping frogs, toads survive
Date: Mon, 4 Jun 2007 15:05:01 -0600
From: Sarah Primeau <sarah_primeau@yahoo.ca>
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References: <00c701c7a6e6$b1076810$7101a8c0@SPRIMEAU>


(From http://www.eurekalert.org/pub_releases/2007-01/uoa-bhf011007.php)

Beavers helping frogs, toads survive

The humble beaver, besides claiming a spot of honour on the Canadian
nickel, is also helping fellow species survive.

Though considered a pest because of the culvert-clogging dams it
builds on streams, the beaver is an ally in conserving valuable
wetland habitat for declining amphibian populations, a University of
Alberta study shows.

The study, conducted in the boreal forests of west-central Alberta,
showed that frog and toad choruses are only present on streams where
beaver dams are present.  While surveying the calls of male frogs and
toads engaged in acoustic displays for females, researchers recorded
approximately 5,000 boreal chorus frogs, wood frogs and western toads
at 54 beaver ponds over a two-year period.  Pitfall traps on beaver
ponds captured 5.7 times more newly metamorphosed wood frogs, 29 times
more western toads and 24 times more boreal chorus frogs than on
nearby free-flowing streams.

The study identifies beaver as a valuable 'surrogate species', said
University of Alberta researchers Dr. Cam Stevens (lead author) and
Dr. Cindy Paszkowski. The work is published in the January 2007 issue
of Biological Conservation. Surrogate species can be indicators of
changes to the environment caused directly or indirectly by human
activities, population changes in other species, or they can act as
'umbrellas' protecting a large number of naturally co-occurring
species.

"The concept of surrogate species in conservation planning offers
simple, ecologically-based solutions to help conserve and manage
ecosystems," said Paszkowski, a professor of biological sciences at
the University of Alberta in Edmonton, Canada.

The beaver pond seems to provide suitable breeding habitats because of
its warm, well-oxygenated water, which enhances development and growth
rates of frog and toad larvae.  As well, the ponds may be less
hospitable to predatory fish because the dams are often located on
small streams where winterkill conditions are common, the study
suggests.

The findings could benefit amphibian conservation efforts for forestry
and energy industries, by making room for beaver dams in their
landscape-use plans, the researchers said.

"The challenge will be to promote modest levels of beaver activity
even where conflicts with human interests might occur, such as areas
designated for tree harvesting and landscapes with high road
densities," Stevens noted.

Beaver may prove useful as a surrogate species in helping conserve
frogs and toads in other remote parts of Canada's boreal forest and
western North America.

###

The study was supported in part by the Natural Sciences and
Engineering Research Council of Canada.

Public release date: 10-Jan-2007
Contact: Bev Betkowski
beverly.betkowski@ualberta.ca
780-492-3808
University of Alberta: http://www.ualberta.ca
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--
Lawrence F. London, Jr.
Venaura Farm
lfl@intrex.net
http://market-farming.com
http://market-farming.com/venaurafarm
http://venaurafarm.blogspot.com/
http://www.ibiblio.org/ecolandtech