The given argument states that the number of amphibians have decreased dramatically since two studies indicate that although seven species were available in the Xanadu National Park in 1975, another study indicates that in 2002 only four species observed in the national park. The author points out that this decline might be explained by the introduction of trout which consumes the amphibian 's eggs into the park. The reasons given by the author might be sound and reasonable at the first glance, however, there are several logical flaws in the argument which undermines the arguer 's conclusion. First, this decline might be due to the sampling errors of the second study. It is likely that the researchers could not find amphibians in nature