Many scientists now believe that human changes to the environment have placed us in another great period of extinction, and that this time the amphibians may be one of the groups most affected. Examples of each have been found to be relevant to specific groups, but in other cases have not applied. It now seems likely that no one cause is behind the varied disappearances. Chyritids are a common fungus, found in all environments yet were never before a problem for amphibians. Daszak et al.
Habitat loss is considered by some experts to be the major factor.
Toxins are also suspected. Scientists agree that whatever the cause, some species and populations are much more vulnerable than others. Even within a single species, some populations may be in decline, whilst others are stable. This has led some scientists to suggest that the disappearances reflect the cumulative impact of local events rather than any single cause. Delis et al.