The herpetologists began to pay attention to the sharp reduction of global amphibious groups in 1989. The cause for the significant extinctive decline in the numbers of several species is a sign of global environmental degradation; and the amphibians are not just affected, avian, reptiles and other forms of life also cause for concern. However, the most attention paid to the amphibians is the natural reserves, national parks and other protective zones for the protection of biological diversity. The most representative case is the Monteverde Claud Forest Preserve in Costa Rica , in which, several unique species of frogs and salamanders, including Bufo periglenes, have disappeared; this phenomenon has become the most evident symbol of decrease in numbers of amphibians.

Although the immediate causes of the decreasing or disappearing of the amphibians in the reserves has ruled out the factor of loss in habitat in these special cases, but it is no doubt that the loss of habitat is still the major reason for the decreasing amphibians around the world. The amphibians are still being threatened by the results of continual human growth such as deforestation, industrialized management of agriculture and pollution.

The common characteristics of the decrease in such a wide range of protective area for amphibians in the world like eastern Australia, the Pacific coasts of northwestern United States, and Central and Southern Americas are: first, the rate of decline is rapid; the species vanish in two to three years; second, a few of the amphibious species in the same area are affected, and not the other species in the same area. The fact has lead to one or multiple factors that can affect amphibious investigation in the global environment, and the cause for particular species to be more affected than others.

A similar cause is the air pollution has increased ultraviolet B radiation that further lead to the thinning of the ozone layer. Surveys conducted in the field and in the laboratory have shown that eggs, embryo and larvae of the amphibians have high sensitivity towards elevated ultraviolet B in general; ultraviolet B could disintegrate their DNA causing abnormal development and death. Nonetheless, a few species are not affected by the increasing ultraviolet B which brings hope to the extent for the influence of ultraviolet B.

Yet, this optimistic view is only temporary. Many amphibians still experience declining numbers without increasing ultraviolet B radiation, or exposing the eggs and the embryos under the sun, especially in the tropical area. Although ultraviolet B has been ruled out for the decrease in the numbers of these species, it still possesses a significant threat; especially for the species breeding in shallow waters of the high altitude where the magnitude of ultraviolet radiation is at a maximum. Recent studies have pointed out that increased ultraviolet B may not lead to mass mortality, but may still bring harmful effects to the amphibians in development; it has restricted the growth and can induce deformities, leading to reduced fecundity of the population.

The amphibians in many areas in the world are threatened by one or multiple artificial chemical substances. These materials are released in the environment in forms of herbicide, pesticides, fertilizers, or the by-products of other industrial processes. There are many known substances that can harm amphibians, among which, the nitrates deserve special attention; it is being used in agricultural fertilizers and accumulates in ponds or streams. Many chemical substances may even become endocrine disruptors that have an effect on the natural hormones of the amphibians. These materials can cause two major harms: first, induce abnormal development in amphibians that lead to deformed mouth, or the disappearance or the increase in number of appendages in most severe cases. Second, even minute concentrations would lead to the feminization of males which can reduce the chances of successful reproduction.

The public in the United States are aware of the deformity in the amphibians. However, the overall relationship between the deformity and the decline in amphibian groups is still unclear. This phenomenon tends to concentrate in a particular area; especially in Minnesota , the “hotspot for deformed frogs.” The deformity is induced by several factors. Some of these factors may entirely be natural as the result from predatory attack or parasites entering the limb bud of frogs or tadpoles leading to the development of two or more limbs in the place of one. As for deformity induced by artificial factors (usually complete or partial disappearance of appendages) include all types of artificial chemical substances, increase in ultraviolet radiation, and inbreeding within small and independent groups. Deformities in a single group are relatively common which has a negative impact on the numbers of local amphibians. Deformities may symbolize the meaning other than the half lethal dose of amphibian death in the environment.

Industrialized activities in many parts of the world have created acid rain, which may fall thousands of kilometers from the source of pollution; for example, the burning of fossil fuels in Britain is the major cause for the formation of acid rains above the Scandinavian Peninsula . Water acidification has negative effect on the eggs and embryo of the amphibians, and can cause decline of amphibian groups in a wide scale.

Many amphibians rely considerably on temporary ponds or streams for breeding; their mating behavior and the climate changes of arriving suitable environment is closely connected. The amphibians in England nowadays are breeding several weeks earlier than those twenty years ago; it is clear to all that this trend is a sign of global warming. Climate changes can influence the amphibians in many different ways, and has caused many groups leading significant decline of numbers. Many frog species in the Monteverde Claud Forest Preserve in Costa Rica have vanished suddenly; this is related to the reduced land being surrounded by low clouds and a series of El Niño phenomena. It has been considered that the decrease in cloud covering has lead to more arid environment and forced the amphibians to concentrate in a few concealed underground locations that increased the possibility for the spreading of parasites and diseases.