Environmental Contaminants Program
U S Fish and Wildlife Service

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New Publication:
image of article from refuge update
"What's Happening to the Frogs?" (pdf) from the September/October 2006 issue of the Refuge Update Bulletin.

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.

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Screen shot of the Fish and Wildlife Service's Year of the Frog website2008 was declared the "Year of the Frog" to highlight this crisis and emphasize the importance of amphibian conservation. In support of this campaign, the Service has created a "Year of the Frog" website. Visit our site to learn what we are doing to help frogs and what you can do.

Amphibian Declines and Deformities

Currently, there are 23 amphibian species classified as endangered or threatened and 11 species waiting to be listed. Overall frog and salamander numbers are declining and the cause, or causes, have not been determined.

Possible causes of amphibian declines include:
  • Changes in climate - acid rain, ultraviolet radiation, drought, ozone layer depletion, etc.
  • Loss of wetlands
  • Invasive predators (such as trout and bullfrogs)
  • Disease (bacteria, viruses, fungus) or parasites
  • Pollution - pesticides, fertilizers, heavy metals, etc.

How is the Division of Environmental Contaminants Involved in Studying Amphibian Declines and Abnormalities?

Evaluating the Health of Our National Wildlife Refuges: Amphibian Abnormalities

The Service 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):
  • Background
  • 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

Fact Sheet on Amphibian Abnormalities and Refuges (pdf)


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.

For further information or to obtain a copy of this report, please see the contact information for the Chesapeake Bay Field Office.

Water Quality

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.

The Task Force on Amphibian Declines and Deformities

Environmental 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.

What 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).

Links to amphibian decline and abnormality sites and information: Links to information for homeowners on proper use of fertilizers:
Last Updated: November 29, 2011