Anthropogenic release of an invasive species
Besides the well-known and most common domestic animals, such as cats and dogs, there are other exotic species that have entered the pet animal trade. This includes reptiles, such as turtles, snakes, and lizards, but also birds, aquatic animals, and so on. Issues arise when the owners are not equipped to keep such pets for as long as they thought. Life changes, moving away, a new kid in the family, or simply the pet grows too big. Circumstances such as these may make the new exotic pet unwanted and lead the human to “release” such captive animal in the wild, perhaps even with good intentions, almost thinking of freeing it. However, we are now much more aware of the potential effects of this so-called voluntary release. Pets that are new to an area can die off in that environment or actually thrive. In the latter scenario, the risk is that the released species can almost take over the new ecosystem, with negative consequences for the native fauna already established there. This is how invasive species occur from pet release, and sometimes consequences can be devastating, like in the case of the Burmese python in the Florida Everglades.
Changes to the Florida Everglades
The Burmese python was introduced in the South Florida Everglades across the 1980s, and with its size and predatory ability, it has decimated the small and medium mammal population present in that area. The Burmese python is the classic example of an invasive species with a very high likelihood of successful establishment. The ecosystem fits perfectly their habitat needs, being humid, muddy, and warm. Moreover, they have no natural predators to contain them in the South Florida Everglades, and female pythons are highly reproductive, laying up to 100 eggs per year (https://www.history.com/news/burmese-python-invasion-florida-everglades). Moreover, the swamps of the South Florida Everglades are very remote, and hard to reach for humans. This impedes efficient surveys, monitoring, and control work which has probably led to the exponential increase of pythons behind the scenes. The degree to which the Burmese python has decimated the local biodiversity is extremely alarming. Some small mammal species dropped by 90%, and some completely disappeared from those habitats. However, Burmese phyton threats do not stop here.
A new pathogen, a new naïve host
Along with their predatory skills, Burmese pythons brought with them a new pathogen into the South Florida Everglades: lung parasite Raillietiella orientalis (https://reptilesmagazine.com/floridas-invasive-burmese-pythons-spreading-disease-to-native-snakes-study-says/). This disease is being passed on from Burmese python into naïve native snakes, which have not been exposed to this pathogen before. Consequences from this kind of spillover can be very dangerous for the novel host. Moreover, the decrease in the mammal population brought by the Burmese python has led a mosquito-borne disease to possibly change its course (https://royalsocietypublishing.org/doi/10.1098/rsbl.2017.0353).
We can identify this general issue under the umbrella of One Health. The consequences and cascades that have resulted from a few isolated actions witness how everything really is connected. Human decisions will influence ecosystem dynamics, which will modify infectious disease trajectory, with consequences on the health of the environment, animals, and back to humans too. Being conscious and aware of the inherent interconnectedness of all realms can help operate better decisions in the future. The One Health philosophy teaches us, with many examples such as the Burmese python invasion, that planet health is based on delicate dynamics between humans, animals, and the environment.
Take home message: please do not release your exotic pets in the wild!
By Costanza Manes, One Health Research Fellow