Amphibian Declines and Deformities
As of December 2012,
there were 29 amphibian species classified as endangered
or threatened and 5 species waiting to be listed.
Overall frog and salamander numbers are declining and
the cause, or causes, have not been determined.
of amphibian declines include:
- Changes in
climate - acid rain, ultraviolet radiation, drought,
ozone layer depletion, etc.
- Loss of wetlands
predators (such as trout and bullfrogs)
- Disease (bacteria,
viruses, fungus) or parasites
- pesticides, fertilizers, heavy metals, etc.
is the Division of Environmental Contaminants Involved
in Studying Amphibian Declines and Abnormalities?
the Health of Our National Wildlife Refuges: Amphibian
helps conserve habitat for fish and wildlife through
the National Wildlife Refuge System, the world's largest
and most diverse collection of lands set aside specifically
for wildlife. To ensure the health of this habitat, Service
environmental contaminant specialists monitor the effects
of contamination on fish and wildlife found on refuges.
Many amphibian species are sensitive to a variety of
environmental stresses and may be good early indicators
of the health of their environment. For this reason,
the Service has a keen interest in determining if amphibian
abnormalities are occurring on National Wildlife Refuges.
On July 6, 2000, the Service launched a nationwide survey
of abnormal amphibians on wildlife refuges. If abnormal
amphibians are found, the Service will then seek to identify
the cause, or causes, of the abnormalities and provide
concrete management guidelines for wildlife refuges and
other land managers to address the problem.
Abnormal Amphibian Survey Standard Operating Procedures (SOPs):
- Abnormality Classification SOP
- HTML - for viewing on the web
- PDF - for downloading
- Photos - examples of different amphibian abnormalities
- Other SOPs
- HTML - for viewing on the web
- PDF- for downloading
Sheet on Amphibian Abnormalities and
The Service's abnormal amphibian surveys have resulted in several journal publications. Two of these publications focus on the disease caused by Batrachochytrium dendrobatidis (which is also known as Bd, chytrid fungus, or the amphibian chytrid fungus). A third publication is a summary of results from the 2000-2006 Alaskan abnormal amphibian surveys. This publication examines skeletal abnormalities in wood frogs (Rana sylvatica).
Reeves, M.K. and D.E. Green. 2006. Rana sylvatica Chytridiomycosis. Herpetological Review. 37 (4): 450.
The above article documents the first report of a Bd-infected frog from Alaska. The infected sub-adult wood frog was found dead in 2002 at a site on the Kenai National Wildlife Refuge.
Reeves, M.K. 2008. Batrachochytrium dendrobatidis in Wood frogs (Rana sylvatica) from three national wildlife refuges in Alaska, USA. Herpetological Review. 39 (1): 68-70.
In the above article, wood frogs from three National Wildlife Refuges in Alaska (Innoko, Kenai, and Tetlin) were sampled and screened for Bd.
Reeves, M.K., C.L. Dolph, H. Zimmer, R.S. Tjeerdema, and K.A. Trust. 2008. Road Proximity Increases Risk of Skeletal Abnormalities in Wood Frogs from National Wildlife Refuges in Alaska (pdf) Environmental Health Perspectives 116(8): 1009-1014.
In addition to these publications, the Service's abnormal amphibian surveys also have resulted in two book chapters:
Eaton-Poole, L., A.E. Pinkney, D.E. Green, D.R. Sutherland, and K.J. Babbitt. 2003. Investigation of Frog Abnormalities on National Wildlife Refuges in the Northeast U.S. In: G. Linder, S. Krest, D. Sparling, and E. Little, eds. Multiple Stressor Effects in Relation to Declining Amphibian Populations. ASTM International, West Conshohocken, PA. pp.63-78.
Turley, S.D., L. Eaton-Poole, A.E. Pinkney, M.A. Oborn, and D.T. Burton. 2003. Evaluation of the Potential Impact of Water and Sediment from National Wildlife Refuge Sites Using a Modified Frog Embryo Teratogenesis Assay-Xenopus (FETAX). In: G. Linder, S. Krest, D. Sparling, and E. Little, eds. Multiple Stressor Effects in Relation to Declining Amphibian Populations. ASTM International, West Conshohocken, PA. pp. 79-95.
Finally, Service Environmental Contaminant (EC) biologists have initiated two separate EC investigations. One investigation is complete, while the other investigation is ongoing. The citation for the completed investigation is:
Pinkney, A.E., L. Eaton-Poole, E.M. LaFiandra, K.J. Babbitt, C.M. Bridges Britton, E.E. Little, and W.L. Cranor. 2006. Investigation of Contaminant Effects on Frog Development at Great Bay National Wildlife Refuge, Newington, NH. CBFO-C0602 & RY2006-NEFO-EC-01. U.S. Fish and Wildlife Service, Chesapeake Bay Field Office, Annapolis, MD. 288 p.
The Service works
with States, local communities, and other Federal agencies
to ensure that water quality standards
protect natural resources. The Service's expertise in determining
the effect of proposed standards on fish and wildlife resources
is broadly recognized. It is this expertise which is used
in developing protective standards.
Force on Amphibian Declines and Deformities
contaminants staff participate in the Task Force on Amphibian
Declines and Deformities (TADD). TADD was established
by Secretary of the Interior, Bruce Babbitt, in response
to concerns about the declining numbers and overall health
of amphibian populations. TADD's mission is to "promote
and coordinate Federal agency activities to identify
the factors responsible for population declines, and
implement conservation and management activities to arrest
or reverse these declines". The Service's Division
of Environmental Contaminants is an active participant
in three of the TADD Working Groups: Science, Conservation,
and International Affairs.
Can You Do To Help Amphibians?
You can help keep the environment clean and the frogs
healthy by changing the way you care for your yard. Check
out our Homeowner's
Guide to Protecting Frogs - Lawn and Garden Care (pdf).
Amphibian decline and abnormality sites and information:
- A New Threat
to Frogs (U.S. Fish and Wildlife
Service. Endangered Species Bulletin. September/October
Declines: an issue overview (3MB pdf) -
Task force on Amphibian Declines and Deformities.
- Frog Chytrid fungus. New South Wales (NSW), Australia, National Parks and Wildlife Service,
- North American Reporting Center for Amphibian Malformations
- Amphibians Home Page at NBII (National Biological Information Infrastructure)
- Amphibian Specialist Group (ASG) - part of the International Union for Conservation, Species Survival Commission (The Declining Amphibian Populations Task Force is now part of ASG)
- Amphibian Research and Monitoring Initiative (ARMI) - U.S. Geological
- Amphibian Declines and Deformities - U.S. Geological Survey, National Wildlife Health Center
for North American Herpetology
- North American
Amphibian Monitoring Program
- The Herptox Page - The effects of environmental contaminants on
reptiles and amphibians
- Amphibiaweb - Information on all aspects of amphibian biology
- Declining Amphibians Forum - University
of California, Berkeley - University of Washington
- Global Amphibian Assessment - conservation status information for the world's 5,743 known species of amphibians.
- Amphibian Ark - coordinating the effort to conserve select species of amphibians in zoos and aquariums with the hope that the species can be reintroduced to the wild at a later stage.
- Partners in Amphibian and Reptile Conservation - members include individuals from state and federal agencies, conservation organizations, museums, pet trade industry, nature centers, zoos, energy industry, universities, herpetological organizations, research laboratories, forest industries, and environmental consultants.
- Association of Zoos & Aquariums Amphibian Conservation Program
Pollution Control Agency: Deformed Frog Information
- Save the Frogs - a nonprofit organization dedicated to amphibian conservation. Save the Frogs!
Information for homeowners on proper use
What is the Difference Between a Malformation and Deformity?
The phrases abnormality, malformation, and deformity are often used interchangeably. However, a true malformation is a biological problem that occurs during development, causing an organ or body part to form improperly. A deformity is usually the result of trauma to a previously normal body part (a foot lost to a predatory beetle, for example). Both malformations and deformities are abnormalities.