Arizona Amphibians

» Posted by Garry Rogers on Oct 28, 2011 in Amphibians, Endangered Animals, Human Impacts, Wildlife | 2 comments

Arizona Amphibians Are Declining

Arizona’s amphibians aren’t doing very well.  It seems that the more a species depends on water, the greater its risk of extinction.  Most of Arizona’s fish and many of its mollusks are in danger.   There is very little local data for our amphibians, but it is well documented that frogs and toads are disappearing around the world.  The causes are a ‘perfect storm’ of surface water diversion and use, water pollution, disease, and predation by invasive species.

The photograph shows a Woodhouse’s Toad, often heard crying in the woods along the Agua Fria River in central Arizona.

Pollutants in streams and lakes produce physical malformations—extra limbs, crooked or missing limbs, and facial disfigurement – that have been found in more than 60 U. S. amphibian species.  More than half the individuals in some populations are malformed.

Adding to the effects of water pollution, a fungal disease is causing even greater devastation than the white-nose syndrome described earlier for bats.  The disease is known as chytridiomycosis (Batrachochytrium dendrobatidis) or Bd.  “Chytridiomycosis caused by Bd infects and severely injures numerous amphibian species.

Recently completed surveys found Bd in several watersheds within Arizona, particularly in central and southeastern portions of the state.  Surveyors found Bd in 92 out of 166 animals tested in Arizona, and six out of six tested in Lake Pleasant (Amphibiaweb and www.bdmaps.net).

The Arizona Game and Fish Department (AZGFD) lists the American Bullfrog as one of its ten most unwanted invasive species.  Bullfrogs prey on other frogs and small creatures, and have altered species assemblages wherever they have become established.  Moreover, Bullfrogs are a significant carrier of Bd and may be one of the early vectors of its spread.  However, Bullfrogs are not immune to Bd or the effects of human wastes in the water.  Bellows of Bullfrogs in the stock watering ponds near my house have declined steadily for several years.

Field guides are available online (Arizona Herpetological Association, Brennan, 2008), and in print (Bishop, 1962, Stebbins, 1966).

Arizona Amphibian References

Amphibian Conservation Alliance:  http://www.frogs.org/index.asp.

Amphibiaweb:  http://amphibiaweb.org/chytrid/chytridiomycosis.html

Bishop, S.C.  1962.  Handbook of salamanders.  Hafner, New York, NY.  555 p.

Brennan, T.C.  2008.  Online field guide to reptiles and amphibians of Arizona:  http://www.reptilesofaz.com/.

Global Amphibian Assessment:  http://www.globalamphibians.org/overview.htm.

NBII.  U. S. National Biological Information Infrastructure:  http://www.nbii.gov.

Partners in Amphibian and Reptile Conservation:  http://www.parcplace.org/.

Stebbins, R.C.  1966.  A field guide to western reptiles and amphibians.  Houghton Mifflin, Boston, MA.  279 p.

U. S. Endangered Species Act.  1973. The act and related laws are discussed at:  http://www.fws.gov/laws/lawsdigest/ESACT.html.

U. S. Forest Service.  2007.  Regional Forester’s list of sensitive animals:  http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev3_021328.pdf.

Arizona Amphibian Checklist

I compiled the checklist from the National Biological Information Infrastructure (NBII) website, the Arizona Game and Fish Department website, and other sources in the Reference list.

Symbols in the left check box:  S = Sensitive species (U. S. Forest Service), ** = Introduced species, T = Threatened (U. S. Endangered Species Act), E = Endangered (U. S. Endangered Species Act).