Burmese pythons (Python bivittatus) are native to Southeast Asia. However, since the end of the 20th century, they have become an established breeding population in South Florida. The earliest python sightings in Florida date back to the 1930s, and although Burmese pythons were first sighted in Everglades National Park in the 1990s, they were not officially recognized as a reproducing population until 2000. Since then, the number of python sightings has exponentially increased, with over 30,000 sightings from 2008 to 2010.

Burmese pythons prey on a wide variety of birds, mammals, and crocodilians in the Everglades. Pronounced declines in several mammalian species have coincided spatially and temporally with the proliferation of pythons in South Florida, indicating the already devastating impacts upon native animals. The importation of Burmese pythons was banned in the United States in January 2012 by the U.S. Department of the Interior.

Introduction Burmese pythons were introduced to Florida in the 1970s as part of the exotic pet trade. Many owners who found it challenging to care for these snakes released them into the wild. In 1992, Hurricane Andrew destroyed a python breeding center. The resulting release of hundreds more snakes was said to have contributed to the population, though research shows that the population is more likely to have been established in other areas, more likely by breeding of a small number of founding specimens, most likely former pets.

Invasive impact

Burmese pythons in the state of Florida are classified as an invasive species. They disrupt the ecosystem by preying on native species, outcompeting them for food or other resources, and/or altering the physical environment. They are comparable in size or even larger than adult native snake species and quickly reach sizes that reduce their vulnerability to predation. The native American alligator is known to be prey, a predator, and a competitor of the serpent, depending on the size of the individuals.Gator-guzzling python comes to messy end. Associated Press (October 5, 2005). Retrieved 2008-03-11.Butler, Rhett A. (October 5, 2005) Python explodes after swallowing 6-foot alligator in Florida Everglades. Mongabay.com. Retrieved 2008-03-11. Bobcats and vultures have been observed raiding python nests for eggs.An unexpected predator is raiding Burmese python nests in the Everglades, Miami Herald, May 21, 2026

The high reproductive potential, rapid sexual development, and longevity of Burmese pythons make it difficult to control the population by removing individuals. A typical female breeds every other year, produces a clutch of between 20 and 50 eggs, and can live for 20 years or more.

Additionally, as predators and dietary generalists, Burmese pythons target a wide array of taxonomic groups.Reed, Robert N., John D. Willson, Gordon H. Rodda, and Michael E. Dorcas. "Ecological Correlates of Invasion Impact for Burmese Pythons in Florida." Integrative Zoology 7, no. 3 (September 2012): 254–70. doi:10.1111/j.1749-4877.2012.00304.x. Thus, they are not dependent upon a specific prey species. The flexible dietary requirements of Burmese pythons enable them to survive for long periods of time without food, but when prey is readily available, they will eat regularly.

Severe declines in mammalian populations across the Everglades may be tied to the proliferation of pythons.Dorcas, M. E., J. D. Willson, R. N. Reed, R. W. Snow, M. R. Rochford, M. A. Miller, W. E. Mehsaka, Jr., P. T. Andreadis, F. J. Mazzotti, C. M. Romagosa, and K. M. Hart. 2012. "Severe mammal declines coincide with proliferation of invasive Burmese pythons in Everglades National Park." Proceedings of the National Academy of Sciences 109:2418-2422.McCleery RA, Sovie A, Reed RN, Cunningham MW, Hunter ME, Hart KM (2015) Marsh rabbit mortalities tie pythons to the precipitous decline of mammals in the Everglades.PROC B, 282, 1805, in press Comparisons of road surveys conducted in 1996–1997 (before proliferation) and 2003–2011 (after proliferation) indicated alarming declines in the frequency of raccoon, opossum, bobcat, rabbit, fox, and other mammalian species sightings, but the validity of the findings and specific numbers has been questioned due to methodological inconsistencies. Nonetheless, declines were also observed where pythons were only recently documented, and the greatest mammalian abundances were observed outside of the python's current range. Burmese pythons were the dominant predator of reintroduced marsh rabbits (Sylvilagus palustris) in Everglades National Park, and predation by pythons extirpated the rabbit population in less than 11 months.McCleery RA, Sovie A, Reed RN, Cunningham MW, Hunter ME, Hart KM (2015) Marsh rabbit mortalities tie pythons to the precipitous decline of mammals in the Everglades.PROC B, 282, 1805, in press.

In the Everglades

The Everglades is a region of tropical wetlands comprising the lower third of the Florida peninsula. Only 25% of the original Everglades remains, protected within Everglades National Park. The climate of South Florida and the location of the Everglades, surrounded by a metropolitan area to the east, Naples to the west, and Florida Bay to the south, make it particularly vulnerable to infestations of exotic species. Miami, in particular, is the hub for the exotic pet trade in the United States. Although the exact origin of Burmese pythons in the Everglades is unknown, likely, many were once pets released by owners who found them too difficult to care for.Dorcas, M. E., and J. D. Willson. 2011. Invasive pythons in the United States: ecology of an introduced predator. Athens, GA: University of Georgia Press. However, the majority of experts concur that the python population grew particularly after Hurricane Andrew. The category 5 storm destroyed a python breeding facility, which released numerous snakes into the adjacent swamps. An evaluation of the genetic structure of Burmese pythons sampled from Everglades National Park determined that the population is genetically distinct from pythons sampled in their native range. Still, within the Everglades population, there is little genetic diversity.

In 2001, the United States Geological Survey began a 10-year period analysis of 400 pythons captured in the Everglades. The survey discovered that there existed a tangled genetic tree between these captured snakes, and that hybrid pythons were manifesting within the Everglades. Thirteen out of the 400 pythons analyzed had genetic signatures of the Indian rock python within their DNA. Indian rock pythons are a smaller and faster species than the Burmese python.

Estimating the population of Burmese pythons in the Everglades is challenging due to the species' secretive nature and the limited ability to conduct traditional mark-recapture assessments.Dorcas, M. E. and J. D. Willson. 2009. Innovative methods for studies of snake ecology and conservation. In S. J. Mullin and R. A. Seigel (Eds.). Snakes: ecology and conservation. Ithaca, NY: Cornell University Press. Namely, it is counterintuitive to the primary goal of python removal to return captured pythons to the wild.

Furthermore, the low detectability of pythons means that even if mark-recapture studies could be conducted, they would require more research effort than is currently feasible. Pythons spend the majority of their day in hiding, whether in burrows or aquatic habitats. One study indicated that even seasoned herpetologists showed only a 1% efficacy in detecting pythons housed in a seminatural environment.Dorcas, M. E. and J. D. Willson. 2013. Hidden giants: problems associated with studying secretive invasive pythons. In: W. Lutterschmidt (ed.), Reptiles in Research: Investigations of Ecology, Physiology, and Behavior from Desert to Sea. Nova Science Publishers, Inc., Hauppauge, NY. Consequently, estimates of python populations range from at least 30,000 to more than 300,000.Snow, R. W., K. L. Krysko, K. M. Enge, L. Oberhofer, A. Warren-Bradley, and L. Wilkins. 2007a. "Introduced populations of Boa constrictor (Boidae) and Python molurus bivittatus (Pythonidae) in southern Florida." Pp 416-438. In R. W. Henderson and R. Powell (Eds.). Biology of the Boas and Pythons. Eagle Mountain, UT: Eagle Mountain Press.

Spatial ecology Several attempts have been made at better understanding the spatial ecology of Burmese pythons in the Everglades, including capture analysis and radio telemetry studies. Since the recognition of the breeding population of pythons, researchers have made an effort to note the capture history (date, location, and time) as well as characteristics (mass, length, sex, reproduction condition, and gut contents) of each animal to better characterize the python's activity patterns, spread, and ecology.Dove, C. J., R. W. Snow, M. R. Rochford, and F. J. Mazzotti. 2011. "Birds consumed by the invasive python (Python molurus bivittatus) at Everglades National Park, Florida, USA." The Wilson Journal of Ornithology 123:126-131. More than 2,000 pythons have been captured since 2005, including hatchling pythons, gravid females, and adults in excess of () in total length. Gut analyses indicate that captured pythons consume nearly any bird, mammal, or alligator found in the Everglades, including nationally endangered Key Largo woodrats (Neotoma floridana smalli) and wood storks (Mycteria americana).Snow, R. W., Brien, M. L., Cherkiss, M. S., Wilkins, L., and Mazzotti, F. J. 2007b. "Dietary habits of the Burmese python, Python molurus bivittatus, in Everglades National Park, Florida." Herpetological Bulletin 101:5-7.

Radio telemetry involves the use of small, surgically implanted radiotransmitters to track the movement patterns of captured and released animals over extended periods.Reinert, H. K., and D. Cundall. 1982. An improved surgical implantation method for radiotracking snakes. Copeia 1982:702-705. A 2014 study suggests that Burmese pythons have navigational map and compass senses.Pittman, S. E., K. M. Hart, M. S. Cherkiss, R. W. Snow, I. Fujisaki, B. J. Smith, F. J. Mazzotti, and M. E. Dorcas. "Homing of Invasive Burmese Pythons in South Florida: Evidence for Map and Compass Senses in Snakes." Biology Letters 10, no. 3 (March 19, 2014): 20140040–20140040. doi:10.1098/rsbl.2014.0040. In contrast to previous research that documented the poor navigational abilities of terrestrial snakes, the movement behavior of the Burmese python seems to be nonrandom. The movements of 12 adult Burmese pythons in Everglades National Park were tracked following their translocation from their initial locations. Five of the six snakes that were displaced from their capture sites exhibited oriented movement, returning to within of their original locations. This homing ability of the Burmese python is therefore an additional factor that must be considered in predictions of the future range of the python within the southern US and the management of the current population within South Florida.

They have carried Raillietiella orientalis (a pentastome parasitic disease) with them from SE Asia. Other reptiles in Florida have become infested, and the parasite appears to have become endemic.

Risk assessment