A variety of threats are impacting amphibian species around the world, causing the massive declines documented here. To better understand the leading threats to amphibians, the assessment recorded known threats to each amphibian species using a standardized list (IUCN Threats Classification Scheme) of major threats. A summary of the number of species affected by each threatening process is shown in Figure 11.
Habitat loss and degradation are by far the greatest threat to amphibians at present, affecting nearly 4,000 species. The number of species impacted by habitat loss and degradation is almost four times greater than the next most common threat, pollution. Although disease appears to be a relatively less significant threat for amphibians, for those species affected, it can cause sudden and dramatic population declines resulting in very rapid extinction. In comparison, although habitat loss and degradation affect a much greater number of species, the rate at which a species declines is usually much slower, and there are a number of strategies, such as the creation of protected areas, to counter this threat.
Information has not been collected during the assessment on the relative importance of one threat compared with another for a particular species. Development of such information in the future is a priority and will enable a more complete analysis of significant threats to amphibians.