Scientists were initially unconvinced that the decrease in the number of amphibians – animals such as frogs that live on land and in water – was real, because amphibian populations are notorious for fluctuating widely. However, after statistical evidence showed that the declines were far more widespread than would reasonably be expected by chance, most researchers agreed that something was seriously wrong. Reports of declines and extinctions accelerated during the 1990s, and the observations indicated that something specific and troubling was happening to amphibians. At one locale in Costa Rica, 40 per cent of the local amphibian species disappeared over a short period. The loss of amphibian species not only contributes to the world’s biodiversity crisis but also has remarkable implications for the ecosystems where the declines occur. Without amphibians, links to food webs are broken, and other organisms suffer in often unpredictable ways. Although some of the earliest amphibian declines were recorded in the US, much of the scientific literature focuses on decreases in tropical countries, where losses have often been more dramatic and have involved a larger number of species. This has led to the curious problem of declines in temperate amphibian species receiving insufficient attention.