Wednesday, June 26, 2013

Snake invaders

Scientific support for Burmese python management in Florida:

The Burmese python is native to Southeast Asia. In south Florida, they are nonnative and considered to be invasive (not constrained by natural factors). The temperate climate and natural surroundings of the Florida Everglades enable this species to thrive. The Burmese python has established breeding grounds within these habitats; specifically the Everglades National Park boundaries. 

Figure 2 below illustrates the number of pythons removed from the Everglades National Park through 2007; indicating expanding populations.

The natural history of the species directs the potential for triggering large, adverse impacts on the ecological make-up of the Greater Everglades and surrounding areas. The Burmese python is known as generalist predator; which means their diet is widely varied (e.g. mammals, birds, reptiles, amphibians and fish species). This species is long lived (up to 25 years), have a high fecundity (high rates of reproduction), tolerate diverse habitat and can travel long distances.

The average clutch size (number or eggs) of the Burmese populations in South Florida is found to be approximately 36; however can be as high as 100. The hatchlings are larger than native species, making them less vulnerable to prey. The largest Florida snake (Indigo Snake) reaches 8.5 feet in length. The average Burmese python is 23 feet long.

Being exceptional swimmers, the Burmese python poses a significant risk to surrounding ecologically vulnerable areas such as the Florida Keys. The endangered Key Largo wood rat (Neotoma floridana smalli ); wading bird colonies and the federally endangered Indigo snake (Drymarchon couperi) are all at a higher risk due to the python invasion (Harvey,, 2013).

According to the United States Geological Service, once an invasive species becomes established, it is very hard to eradicate. With increasing populations and rising climate temperatures, these invasive pythons could move into several other areas of the United States. Prior evaluations of saltwater tolerance of the Burmese python have been underestimated. Accordingly, previous habitat predictions based on salt water barriers need to be re-evaluated (Hart, et. al., 2012). 

Figure 3 below demonstrates modeled projections of habitat expansion of the Burmese python; supporting the development of aggressive management programs (USGS, 2013).

Harvey, R., Brien, M., Cherkiss, M., Dorcas, M., Rochgord, M., Snow, R., Mazzotti, F., 2013. Burmese Pythons in South Florida: Scientific Support for Invasive Species Management. IFAS Extension, University of Florida. Online. Available at: [Accessed on 18/04/2013].

Hart, K., Schofiled, P., Gregiore, D., 2012. Experimentally derived salinity tolerance of hatchling Burmese pythons (python molurus bivittatus) from the Everglades, FL (USA). Journal of Experimental Biology and Ecology. 413.pp.56-59.

USGS, Unites States Geological Service, 2013. Everglades Python Prey Study: Frequently Asked Questions. Online. Available at: [Accessed on 18/04/2013].

USGS, Unites States Geological Service, 2013. Illustration. Projected range expansion of python.

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