Xandu National Park.
In the letter, the reader suggests that there has been a decline of amphibians in Xandu National Park due to the introduction of trouts in 1975. The author’s hpyothesis is based on the 1975 widlife census and a observation in the year 2002. The authors arguments may be correct, however his arguments are based on three assumptions which need a more detailed elaboration.
First, the authors cites a comparision between the 1975 wildlife census and 2002 observation in the Xandu National Park. There may be diffference between the manner in which these two things might have been conducted. The 1975 census might have been done more scientifically whereas the 2002 is an observation by the existing forest staff or visitors. There might be a difference in month during which the survey was conducted. If 1975 was conducted in summer and the 2002 was conducted in winter. The lower numbers might be due to the fact that during winter most of the animals might have been in a hibernation phase. These scenarios if true, deminish the credibility of the authors assumptions.
Second, author assumes that there has been a substantial decline in the numbers of amphibians worldwide due to pollution of water and air while the decline of amphibians in Xandu National Park is due to introduction of trout. This might not be the case. There can be polluting industries nearby Xandu National Park and this might be affecting the numbers of amphibians in the park. Further there might be the case where globally trout popullation increased and which has cuased a global decline in amphibians. These facts hamper the authors contentions.
Laslty, the author assumes that the trout eats amhibian eggs which causes the reduction in amphibians in the park. This might not indicate the decline. We need to consider the reason that there might be substantial number of amphibians eggs which can accomodate the needs of the trouts. Also, there might be a possibilty that the trout popullation might have decreased substantially from 1975. If either of the scenario proves true, then the authors aurgument does not hold water.