The following is a letter to the editor of an environmental magazine."Two studies of amphibians in Xanadu National Park confirm a significant decline in the numbers of amphibians. In 1975 there were seven species of amphibians in the park, and there were

Even though the explanation proposed to explain why amphibians have drastically reduced from 1975 to 2002 in Xanadu National Park seems plausible, there are alternatives to respond the same fact.

On account of the large span between the two studies, 27 years, many phenomena could have happened causing the reduction in the numbers of amphibians. One likely scenario is that half of the amphibian specimens in 1975 were already very old, which passed away naturally a few years later as no creature can escape the final destiny forever. Or even if they were not elderly amphibians, could have died from animal chronical diseases since no human was taking care of them each day like in the zoos, otherwise the reason of this reduction would be clearly stated.

Besides the natural death as a factor of the drastic descending in the numbers of amphibians over this period, other species that are predators other than trout could have also increased in the park. Therefore, it is necessary to observe the evolution of other species at the same time as counting amphibians specimens in the two years in order to draw a different conclusion: if predator species inhabitants correlate inversely to the amphibians, then it is probably the former had preyed on the later which ensued the reduction in amphibians.

Other than their death of any kind, they could have gone out of the park unconsciously or by storms or even human beings could also have been responsible for the disappeared members. To illustrate, some of the visitors to the park could have been amphibian fanatics who could not resist the thought of taking some specimens with them either as pets or for experiments. Thus, if many of them have done it, this could have led to amphibians reduction.

In summary, there is no single explanation that accounts for 100% of the fact, instead, it is normally many agents altogether that have caused the effect, and in regard to which one has more weight on it requires further study. In this case, the combination of the introduction of the trout into park's water along with other inherent factors of the species like age or illness and extrinsic ones as meteorological or human beings could have caused amphibians reduction in the park.