Major Threats

A variety of threats are impacting amphibian species around the world, causing the massive declines documented during the GAA. To better understand the leading threats to amphibians, GAA researchers recorded known threats to each amphibian species using a standardized list (IUCN Major Threat Authority File) of major threats. A summary of the number of species affected by each threatening process is shown in Figure 11.

Figure 11. Major Threats to Amphibians.

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 GAA on the relative importance of one threat compared to another for a particular species. Development of such information in the future is a priority for the assessment and will enable a more complete analysis of significant threats to amphibians.