This being the end of "National Invasive Species Awareness Week", I wanted to draw attention to one of the most classic and quintessential examples of how invasive species have been introduced by people, resulting in great devastation to the local ecosystem. This post will take us to the warm and tropical state of Florida, where the exotic Burmese python has been thriving since being introduced in the 1980s! Originating from Southeast Asia, Burmese pythons are heavier and stronger than any native snake found in Florida. Growing up to 20 ft in length, they are strong enough to eat adult deer, bobcats, rabbits, birds and alligators (sometimes ending poorly for both the python and alligator!)
Scientists have reported decreases in various animals in the Southern Florida region. Dorcas et. al. (2012) looked at the presence of mammals in the Everglades National Park (ENP) where common roadkill organisms found between 1993 and 1999 were raccoons, Virginia opossums and rabbits. Pythons were considered established in the area in the year 2000. From 2003 to 2011 they reported decreases in the following animals with percentage in parenthesis: raccoons (99.3%), opossums (98.9%), white-tailed deer (94.1%), and bobcats (87.5%). No foxes or rabbits were found during this time period. In peripheral areas where pythons were recently documented, Dorcas et al. (2012) found lower encounter rates by (in parenthesis) for the following organisms: raccoons (89%), opossums ( 44%), and foxes (83%). Authors further wrote " Observation frequency of raccoons and opossums at two extralimital locales were similar to historical sighting frequencies in ENP and were substantially higher than sighting rates in recent surveys of ENP and peripheral locales ". This suggests that the Burmese python have a role to play in these findings. Some species such as turtles may benefit as raccoons, foxes and opossums have been known to decimate turtle nests.
Invasive species are also problematic because they are easily able to adapt to their new areas. Not only does the Florida environment contain proper food and habitat for them, but scientists have found evidence that they can breed with other species. Hunter et al. (2018) collected Burmese python tissue samples from Everglades National Park and found some had genetic signatures of Indian rock python in their mitochondrial DNA. While it was not known if the interbreeding occurred in the wild or in captivity, the potential exists for it occur in the wild, and may result in progeny that can adapt to a broader type of habitat, and be faster/sleeker than Burmese python that has no other species in its DNA.
There are two main ways this (and other invasive snakes such as the Common boa and N. African python) have made their way into the Everglades, forests and cites. The first being released by careless pet owners who either didn't do their research on how big they get, understand how much care/money was needed, or lack a future plan for unexpected changes in health/finance...). The second involves snakes escaping due to unfortunate environmental circumstances such as floods, hurricanes, fires etc... It is without saying that no pet, be it a snake, cat, dog, fish etc. should be released into the wild. Always have a back up plan, contact reputable owners/retailers or local organizations for help in re-homing any organism that needs it. If you cannot commit to a pet for the entirety of its life, there are many groups, pet owners and zoos that do outreach and education events where you can responsibly interact with these beautiful organisms.
For more information:
Dell'Amore, C. 2012. Pythons Eating Through Everglades Mammals at "Astonishing" Rate?. National Geographic Website:
Dorcas. M. E. et. al. 2012. Severe mammal declines coincide with proliferation of invasive Burmese pythons in Everglades National Park. PNAS. 109(7):2418-2422.
Hunter, M.E et. al. 2018. Cytonuclear discordance in the Florida Everglades invasive Burmese python (Python bivittatus) population reveals possible hybridization with the Indian python (P. molurus). Ecology and Evolution. 8(17): 9034-9047.
Shikha Singh is the coordinator for the JLW CISMA. She has a BSc. in Biology from University of Western Ontario, and her master's and PhD at Michigan State University from the Dept. of Fisheries and Wildlife. Her areas of expertise include water quality, water policy, invasive species, education/outreach and public speaking.