Declines in the populations of amphibians (frogs, toads, salamanders, newts, and caecilians) were first highlighted internationally in 1989 at the First World Congress of Herpetology (the study of amphibians and reptiles) in Canterbury, U.K. Many researchers had independently noticed that the populations of frogs they studied were greatly reduced in number or had disappeared altogether from locations in which they had previously been abundant. One such location was in the Sierra Nevada mountains of California.