Amphibian Malformations

In 1996, a group of Minnesota school children on a field trip to a local pond made a disturbing discovery: dozens of frogs with missing limbs and eyes, extra limbs and underformed limbs.  Reports surfaced from other areas of the nation that frogs with similar malformations were present.

In the past decade, extensive research into the malformations phenomena has been undertaken by scientists from government, academic, and non-profit sectors. Scientists have identified several variables potentially contributing to malformations, such as diseases, ultraviolet radiation, contaminants, and predation.  It is probable that malformations are not the result of a single cause, but are rather brought on by different factors in different regions.  The debate over malformations phenomena is far from conclusive, however, and research continues.

In cooperation with the greater scientific community, this Web site serves as a resource for people to learn about amphibian malformations phenomena in North America and for citizens to report on the health of local amphibian populations.

If you have observed malformed amphibians, we encourage you to report your sightings to the North American Reporting Center for Amphibian Malformations (NARCAM) using this site's online reporting form.  You can also get information on the extent of malformation reports received to date, including geographic distribution, information on the types of malformations found and species affected in each area.

Founded and developed by the USGS Northern Prairie Wildlife Research center, NARCAM is now managed by the Southern Appalachian Information Node of the USGS NBII in partnership with the University of Georgia's Savannah River Ecology Lab.

According to the U.S. Geological Survey's National Wildlife Health Center, malformations in amphibians arise from environmental factors that affect individuals at the larval stage of development. Observed malformations have included:

• Missing forelimbs or hindlimbs
• Extra forelimbs or hindlimbs
• Incompletely formed forelimbs or hindlimbs
• Missing eye(s)

Researchers suggest that multiple causes are probably to blame for the malformation instances that have been reported worldwide, and that factors leading to malformations at a particular site may be different from those causing malformations at another site. At this time, the four major environmental factors identified as the causes of malformations are contaminants, nutritional deficiencies, parasites, and injuries from predators (USGS National Wildlife Health Center).