Soaking Up the Sun

14
Feb
2012

Maintaining Basking Sites for California Red Legged Frog at Big Gun Conservation Bank

Back in 2010 we announced the approval by U.S. Fish and Wildlife Service of our Big Gun Conservation Bank.  The Bank, located in Michigan Bluff, outside Foresthill, is home to what may be the largest remaining documented population of California red-legged frogs (CRLF) in the Sierra Nevada.  The California red-legged frog, made famous by the Mark Twain story of the “The Celebrated Jumping Frog of Calaveras County”, is listed as endangered by the U.S. Fish and Wildlife Service. This species once spread far and wide throughout western California and northwest Baja, however mining activities, intensive agriculture and development has limited the range of the species. Historically, the 48-acre site was hydraulically mined for gold in the late 19 century and as a result large pools were formed and have since become prime habitat for the CRLF.  Since 2010, Westervelt Ecological Services (WES) has been working diligently to maintain the site and the population of the species.

One of our most recent maintenance activities included the removal of dense vegetation in several locations around some of the ponds to increase basking sites for the CRLF.  Each of the areas selected for vegetation removal was selected based on several factors.  First, CRLF’s had been observed in the pond during previous surveys.  The pond edge had a gentle slope and shallow water, allowing the water to warm quickly in the late spring.  Finally, vegetation or other escape cover was immediately adjacent to the basking site, acting as a nearby retreat from predators.  All vegetation removed from the basking sites was removed by hand in the late spring under the supervision of a biological monitor.

an image of a California Red-Legged Frog swimming in some murky water

Why is this critical for the frogs?  Basking is important for absorbing solar energy and raising the body temperature of the adults and tadpoles.  This helps a frog have a temperature higher than its environment.  An increased body temperature accelerates growth, digestion and produces fat deposits.

You can see from the photos posted below the difference in vegetation from 2010 to 2011 – after the vegetation has been removed.

2010 copy 2011