"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 abundant numbers of each species. However, in 2002 only four species

The author of the argument asserts that due to introduction of trout in waters of Xanadu National Park (XNP) a number of amphibians has dropped significantly. This author's conclusion is buttressed by several evidences. However, may they have alternative explanations? To answer on this question we need to closer look at the given facts.

First of all, we know from its name that Xanadu National Park is protected by the law as well as all national parks. However, XNP is connected with surroundings and the changes which are take place beyond the boundaries of XNP may affects animals which live in it. For example, some rivers should flow in the park, perhaps some mills and plants are usings this water for manufacturing purposes, these mills may contaminate the water of the river and therfore negatevly impact on such inhabitants of the park as amphibians. Moreover, the water may be used for farming purposes as well. In this case, the waters may be polluted by pesticides such as DDT. In other words, the park is connected with the rest of the state and some actions and events which take place beyond the protected boundaries may negatively affect on the XNP's environment.

Moreover, some global alterations may cause the reduction of the species of amphibians which inhabit the park. For example, an average temperature may slightly decline during the 27 years. Some species of amphibians are sensitive to the temperature of surroundings and they may extinct due this change. Moreover, the park may undergo some severe winters when waters of the park were frozen in this case, the number of amphibians may drop due to the climate disaster. Thus some global weather patterns may influence on the number of amphibians.

Besides, some factors in the park may affect the life of amphibians. Perhaps some other species which eat amphibians were introduced in waters of the park. Moreover, the park may be visited by a large number of people with children and domestic animals. Probably, the visitors may harmfully affect on local inhabitants such as amphibians. For example, children and youngsters may kill the amphibians for fun or destroy their nests accidently. Such animilas as dogs may eat the amphibians as well. Consequently, the trout's blame is not warranted.

In conclusion, despite the fact that the originator of the argument tends to blame introduction of trout as the reason of the extinction of the amphibians, a number of other factors may cause the alteration. The factors may be external such as farming and manufacturing which is probably contaminate the waters, the global changes as well as weather patterns may affect on life of animals. Thus the author's conclusion is unwarranted and trout may be blameless.