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. Source