Reliable reports of amphibians with malformities are centuries old. In fact, malformed amphibians have probably existed for the entire 350 million years of amphibian evolutionary history. What is without a doubt unique about the situation that concerns us now is the number of places with amphibian malformities, and the percentage of individual animals with malformities at these sites. Among field biologists, concern about amphibian malformities piggybacks onto an older concern over amphibian declines. Today, scientists have narrowed down the causes of amphibian declines.
Different factors are more or less important, depending on the species and the region.
The link between amphibian declines and amphibian malformities has remained speculative. Declines are occurring in the absence of malformities. Malformities appear to be occurring in otherwise healthy populations. I suspect that continuous loss to a population of such animals before they have a chance to breed will have harmful consequences for that population over time. There are several reasons for this, but generally, in the information that has been disseminated to the public, scientific facts have competed with issues of subjective bias.