Amphibian Declines and Deformities

Image of an abnormal frog.

Landmark Study Reveals Low National Rate of Frog Abnormalities on Wildlife Refuges

An unprecedented 10-year-study by the U.S. Fish and Wildlife Service shows encouraging results for frogs and toads on national wildlife refuges. The study, published today in the peer-reviewed online journal PLOS ONE, finds that on average, less than 2 percent of frogs and toads sampled on 152 refuges had physical abnormalities involving the skeleton and eyes - a lower rate than many experts feared based on earlier reports. This indicates that the severe malformations such as missing or extra limbs reported in the media during the mid-1990s were actually very rare on national wildlife refuges.

The Service's study also detected areas where sites with higher rates of abnormalities tend to cluster together geographically. Within these regional hotspot clusters, which were found in the Mississippi River Valley (northeast Missouri, Arkansas and northern Louisiana), in the Central Valley of California, and in south-central and eastern Alaska, abnormality frequency often exceeded the national average of 2 percent, affecting up to 40 percent of emerging amphibians in some individual samples.


MORE INFORMATION:

Abnormal Amphibian Program: Background and Standard Operating Procedures (SOPs)

PUBLICATIONS:

In addition to our recent publication in PLOS ONE, Service biologists have produced additional journal publications and book chapters as a result of either our abnormal amphibian program or separate investigations on abnormal amphibians. A list of these publications is provided below.

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.

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.

Reeves, M.K. and D.E. Green. 2006. Rana sylvatica Chytridiomycosis. Herpetological Review. 37 (4): 450.

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.

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.

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.


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).


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Last updated: November 15, 2013