Effects Of Invasive Burmese Pythons On Ecosystems In Southern Florida

Invasive predators can have a detrimental effect on their prey, yet also on non-prey species due to trophic cascades. Python molurus bivittatus (Burmese python) which are native to Asia are an an invasive species that predominates majority of the Everglades in Florida. Since their appearance around 2000 they have significantly reduced the common animals that once lurked in the Everglades. The declines of mammals such as racoons, bobcats, rabbits, and opossums in the everglades have been linked to python predation. The decline of these animals could have certain impacts on other aspects of the ecosystem.

In this scientific article, John Willson experimentally studies the indirect effect of the Burmese pythons on the ecosystems located in southern Florida. In specific, Willson placed artificial turtle nests in places of high python density and low python density to test whether the predation rates by mammals in general would vary.

The hypothesis in this study was that the predation rates of the artificial nest would be at its lowest in the area where pythons have been the longest due to mammal appearances being rare, and higher in areas where pythons have not expanded to. The author had 4 groupings of sites, the core site would be where pythons have been the longest, the peripheral sites were where pythons had been spotted recently, and the extralimital sites were areas where pythons have not been seen yet.

The results of this study were that nest predation was highest at the extralimital sites, lowest at the core sites, and average in the peripheral sites when excluding crows, therefore, these results supported the tested hypothesis.

The study design seemed well thought out as Willson had done research on locations where the artificial eggs would best be placed for this study, appropriately labeling the different sites according to python-density. The introduction of the crows that affected the research helped to prove the integrity of the paper as the researcher could have just left out the data. The paper did not mention an alternative hypothesis, although a recommended one could be that the pythons did not have an indirect effect on the ecosystem.

Recommendations for this study would be to broaden the scope of other factors in the ecosystem that were indirectly affected such as possible overgrowth of surrounding plant-life due to lack of herbivores to keep them at bay. The comparison that was displayed by Wilson between the current indirect affects that the Burmese python is causing in the Everglades to the conditions in Guam by the brown tree snakes further shows that the application of management efforts should be done soon. The researcher prompts that his study provides data that should be a call to action about the need to manage the python population and restore the Everglades to its former diversity.

Scientific Critique

Death feigning is a behavior seen in animals in which they freeze and appear dead when the animal is feeling threatened. This behavior is recognized as an adaptive response by several animals. shown to possibly maximize the species survival. There is little information about death feigning in Asian snakes and no information about death feigning in the Burmese python, python bivittatus. There is a protected area for python is Nepal, however, there are not strong conservation efforts made outside of this area. The researchers in the study documented their observation of a behavior called death feigning in python, where animal acts as though it is deceased with no movement. The researchers were focused on this behavior to expand the knowledge about pythons to suggest that this information would be valuable to further conservation plans in Nepal. In this journal the research was based solely on one incident in which death feigning was observed by a python twice after being rescued from a local home. The researchers concluded that it was likely caused either from being stressed due to human interaction or experiencing starvation.

The researchers in this study were well researched on the concept of death feigning in other species of snakes, however, the experiment itself was not well-executed. The design was based on the observation of only one occurrence of death feigning in pythons in which this behavior was not seen in the 100 other rescue operations that were reported. This experiment could have been better if the researchers had gathered more data from pythons in the wild. There was no hypothesis tested other than a mention in the discussion where the researchers assume that death feigning might be rare in pythons. Since the sample size was so small, the researchers could only make assumptions about the behavior.

Perhaps the researchers could study pythons in other places other than Nepal, such as in the Everglades where they are very abundant. The researchers proposed that this behavior is induced by stress or starvation based on other animals exhibiting the same behavior however, there is a lack of evidence as their data was only based on one test subject. Since the exact cause of the death feigning in pythons is unknown researchers should try to gain a better understanding and discover more samples to test the hypothesis that stress, or starvation could induce death feigning.