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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: Burmese Python

Synonyms and Other Names: Formerly regarded as a subspecies of Indian Rock Python as P. molurus bivittatus (Jacobs et al. 2009).

Taxonomy: available through www.itis.gov

Identification: It is the largest of the three formerly recognized subspecies of Indian pythons (Python molurus). The Burmese python (P.  bivittatus) is a heavy bodied and colorful animal.  A pattern of large reddish brown blotches outlined in cream or gold overlay a base color of pale tan, yellowish-brown, or grey; they have an arrow shaped-marking on the top of their head that points towards their nose (Mehrtens 1987). They are among one of the largest snake species in the world, with every life stage larger than any native snakes found in its invasive range (Harvey et. al. 2008). The Northern African python (Python sebae), another invasive constrictor species in Florida, can be confused with the Burmese python in appearance. However the Northern African python’s pattern on the back is less vibrant/defined than the Burmese python, and the belly scales are a pattern of black and white colorations while the Burmese python belly scales are white (Florida Fish and Wildlife Conservation Commission).

Size: Can grow to 20 feet and weigh more than 250 pounds, with females being larger than males.

Native Range: The Burmese python indigenous range is Northeastern India, East through southern China, Southeast Asia and the Malay Peninsula, but is absent from the Philippines (Mehrtens 1987).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Burmese pythons are large bodied, long lived (15-25 years), constricting snakes found in tropical/ subtropical environments. They are adaptable to a wide variety of habitats, such as grasslands, swamps, marshes, rocky foothills, "open" jungle, woodlands, and river valleys. Populations are dependent upon a permanent source of freshwater and they are excellent swimmers, usually partially or completely submerged in water(Harvey et. al 2008). In their native range, they nest in open-ground sites, under fallen trees, and inside tree holes (Hanslowe et. al. 2016). They eat a wide range of terrestrial vertebrates in their native range including mammals, amphibians, and birds, and are known for the large size of prey items they can devour like leopards and antelopes (Reed and Rodda 2009). A prolific species, these snakes have an average clutch size of 29-50 eggs but they can lay as many as 107 (Brien et al. 2007; Reed and Rodda 2009). The eggs are deposited, incubated, and protected by the female. Hatchlings are 18 to 24 inches long, and leave the nest area soon after hatching, where they can grow quickly given an abundant food supply. Adults may attain lengths of 25 feet, but specimens over 18 feet in length are rarities (Mehrtens 1987). The mating season observed in Everglades National Park occurs between December and April, with females laying eggs from May to June, and eggs hatching between July and August (Harvey et. al 2008). Burmese pythons are social breeders, with aggregations of several males and a single female during breeding season (Smith et. al. 2015). Hanslowe et. al. 2016 study observed a female python coiled around her clutch in a cement culvert, proving they can use anthropogenic structures for nests. Sources of mortality of Burmese Pythons in Florida includes purposeful removal by humans, vehicle collisions, and injury from wildfires or prescribed burns (Wilson et. al. 2011)

Means of Introduction: Biologists believe that most of the pythons found in the Everglades were introduced into the park after being discarded by pet owners (Feanny and Rivers 2004). More than 300,000 Burmese pythons have been imported into the U.S. in the last 30 years for the exotic pet trade (Reed and Rodda 2009). The most likely course of establishment for this species was a small number of individuals being released prior to 1985 (Wilson et. al. 2011).

Status: Established. The first nest was discovered within the Everglades National Park's boundary in 2006 (NPS 2009).

Impact of Introduction:

Summary of species impacts derived from literature review. Click on an icon to find out more...

Ecological	Economic	Human Health

Python bivittatus is a generalist predator that preys upon everything they can fit into their mouths such as small to medium, and sometimes large sized mammals, birds, and reptiles of appropriate size (Mehrtens 1987). Burmese pythons have directly contributed to wildlife populations decreasing within Everglades National Park (ENP), including endangered species (Dove et al. 2011; Greene et. Al. 2007; McCleery 2015; Dorcas et. al. 2012; Boback et. al. 2016; Somaweera et. al 2013). The decline of mammalian predators is correlated with decreased predation on turtle (Wilson 2017) and American Crocodile (Crococylus acutus; Mazzotti et al. 2022) nests. There have been observations of Bobcats (Lynx rufus) eating Burmese Python eggs (Currylow et al. 2022) and adults (McCollister et al. 2021), Florida Black Bears (Ursus americanus floridanus) attacking pythons (McCollister et al. 2021), American Alligators (Alligator mississipiensis) eating adult pythons, and there is speculation that the Florida Panther (Puma concolor) may be a potential predator for pythons as well (Snow et. al. 2007). Indirect effects resulting in trophic cascades that can alter the entire ecosystem are a potential concern with the predation of the Burmese python on so many native species (Wilson 2017).

Burmese pythons are host to parasitic pentastome (Raillietiella orientalis) in their native range and has introduced it to Florida where it has infected native snakes that cooccur with the Burmese python, and even farther North (Miller et. al. 2017).

Risks of a free-ranging Burmese python attacking and killing a human are very low, and between 2006 and 2012, there were 5 reported encounters where a Burmese python attacked biologists, unprovoked, with 2 of them resulting in minor injury (Reed and Snow 2014). The greatest hazard these snakes pose to humans is when they sprawl across roads where they can be a danger to motorists (Harvey et. al. 2008).

Smith et. al (2007) provides realistic associated costs of Burmese python predation in southern Florida ecosystems, assigning monetary ‘take’ values to species listed as endangered or threatened on both state and federal levels and estimating successful predation events on these species. A single predation event can be estimated from $3,495.50 up to $250,000, resulting in costs of $6,000,000 in a single year. Direct management of Burmese Pythons in Florida can cost millions of dollars (see Remarks for more information).

Remarks: Wild native populations are heavily exploited by the exotic leather trade (Mehrtens 1987). The first ever state sanctioned hunting season for pythons captured 37 specimens, ranging in size from hatchlings to ten feet in length (FLDEP 2009). Everglades National Park Service technicians have trained a beagle, Python Pete, to track the scent of the Burmese python in the Park to aid in removal efforts (FIND Somma’s reference for this).  More recently, FWC has used trained dogs to track and find pythons for subsequent removal by their handlers (Haworth, 2020).

The “Judas” technique has proven effective to capture large, reproductive female pythons; A radio-tagged individual (usually a male) is tracked to breeding aggregations that form during breeding season, which then ‘betrays’ the individuals in the said breeding aggregation (Smith et. al 2016).

Extremely high levels of mercury found in pythons coming out of the Everglades make them unsafe to eat, which eliminates serving them in restaurants as a method for controlling populations (Haskins et. al 2019).

In 2010, there were record cold temperatures in South Florida for nine days, with temperatures ranging from −4°C to 10°C. Nine out of ten telemetered pythons tracked had died from the cold snap, and out of 104 non-telemetered pythons found up to a month after the cold event, 40% of them were found dead with mortality resulting from the cold temperatures (Mazzotti et. al 2011).

Environmental DNA (eDNA) analysis is an effective tool for early detection of invasive species like the Burmese pythons; Hunter et. al 2019 identified  positive eDNA detections in Loxahatchee National Wildlife Refuge in 2014 while the first physical before the first physical snake was found in 2016.

Rodda et. al (2009) predicts the Burmese python’s potential range is throughout the Southeast, as far north as Southern Maryland, and as far west as Southern California. Pyron et. al (2008) claims the only suitable habitat for the Burmese python is the current South Florida distribution and extreme southern Texas. An unusually cold period through the southeastern states in 2010 granted the opportunity to test the Burmese pythons resiliency in cold weather. The results were all pythons dying in semi-natural enclosures in South Carolina and seven out of nine dying from cold-induced mortality in Gainesville, Florida, which is approximately  400 kilometers north of their current introduced range (Dorcas et. al 2010; Avery et. al 2010). However, a wild female python was observed performing shivering thermogenesis on her clutch, showing that these reptiles may successfully produce hatchlings in cooler temperatures (Snow et. al 2010).

Groot et al. (2003) identified a case of facultative parthenogenesis in a captive Burmese Python, while Booth et al. (2014) note another unpublished case and discuss the possible mechanisms; together, these findings increase the risk of a single female Burmese Python establishing a viable population.

There is a recorded instance of hybridization in captivity between Burmese Python and African Rock Python (P. sebae), which is also established in Florida (Branch and Erasmus, 1984), leading to concerns that potential wild hybrids could be better competitors and extend the range further north.

The United States Fish and Wildlife Service (FWS) spent $604,656 between 2007-2009 to design python traps, deploy and maintain them, and educate the public in the Florida Keys to prevent the potential extinction of the endangered Key Largo woodrat and other vulnerable listed species. FWS, in partnership with many organizations, has spent more than $6 million since 2005 on finding and implementing solutions to the growing populations of Burmese pythons and other large invasive constrictor snake species in Florida. The National Park Service has spent $317,000 annually on programs dealing with constrictor snake issues in Everglades National Park (Shwiff et. al. 2018). From 1999-2009, federal and state agencies have spent $1.4 million on Key Largo woodrat recovery efforts and $101.2 million on Wood Stork recovery efforts (U.S. Fish & Wildlife Services 2012b).

South Florida Water Management District (SFWMD) and Florida Fish and Wildlife Conservation Commission (FWC) have their own programs (Python Elimination Program and Python Action team, respectively) for python removal where contractors are hired and compensated for size of pythons and their nests found (Rodgers et. al. 2021). A 2019 Everglades Invasive Species Summit presentation on Python Removal Programs states the total budget for all state python removal programs was $637,950, with the average cost to capture a python estimating at $228.82. (Miller et. al 2019). The budget for python control efforts was approved to almost $1 million annually by the SFWMD board in 2019 and both organizations are actively collaborating on a number of initiatives as well as hosting an annual Python Bowl every year (Solomon 2019). Since their formation in early 2017, the two programs have removed over 5,000 pythons (Rodgers et. al 2021).

References: (click for full references)

Brien, M. L., M. S. Cherkiss, V. M. Johnson and F. J. Mazzotti. 2007. Python molurus bivittatus (Burmese Python) clutch size. Herpetological Review 38(3):342.

Boback, S.M., R.W. Snow, T. Hsu, S.C. Peurach, and C.J. Dove. 2016. Supersize me: remains of three white-tailed deer (Odocoileus virginianus) in an invasive Burmese python (Python molurus bivittatus) in Florida. BioInvasions Records 5(4):197-203. DOI: http://dx.doi.org/10.3391/bir.2016.5.4.02.  

Currylow, A.F., M.F. McCollister, G.E. Anderson, J.M. Josimovich, A.L. Fitzgerald, C.M. Romagosa, and A.A. Yackel Adams. 2022. Face-off: Novel depredation and nest defense behaviors between an invasive and a native predator in the Greater Everglades Ecosystem, Florida, USA. Ecology and Evolution 12(2):1-6.

Dove, C.J., R.W. Snow, M.R. Rochford, and F.J. Mazzotti. 2011. Birds consumed by the invasive Burmese python (Python molurus bivittus) in Everglades National Park, Florida, USA. The Wilson Journal of Ornithology 123(1):126-131. DOI: https://doi.org/10.1676/10-092.1.  

Dorcas, M.E., J.D. Wilson, R.N. Reed, R.W. Snow, M.R. Rochford, M.A. Miller, W.E. Meshaka, 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 of the United States of America.  DOI: 10.1073/pnas.1115226109   

Dorcas, M.E., J.D. Wilson, J.W. Gibbons. 2011. Can invasive Burmese pythons inhabit temperate regions of the southeastern United States? Biological Invasions 13:793-802.DOI: https://doi.org/10.1007/s10530-010-9869-6. 

Feanny, C., and K. Rivers. 2004. Predators in paradise. CNN.com. October 22, 2004. Available online at URL http://edition.cnn.com/2004.TECH/science/10/22/predators.in.paradise/10/25/2004 

Florida Fish and Wildlife Conservation Commission. Northern African Python: species profile. Available online at: https://myfwc.com/wildlifehabitats/profiles/reptiles/snakes/northern-african-python/ Accessed on 3/31/2021.

Greene, D.U., J.M. Potts, J.G. Duquesnel, and R.W. Snow. 2007. Python Molurus Bivittatus (Burmese Python). USA: Florida: Monroe Co. Herpetological Review 38(3):355.16657
Hanslowe, E.B., B.G. Falk, M.A.M. Collier, J.M. Josimovich, T.A. Rahill, and R.N. Reed. 2016. First record of invasive Burmese Python oviposition and brooding inside an anthropogenic structure. Southeastern Naturalist 15(sp8):103-106.DOI: https://doi.org/10.1656/058.015.sp809

Harvey, R.G., Brien, M.L., Cherkiss, M.S., Dorcas, M.E., Rochford, M., Snow, R.W., and Mazzotti, F.J., 2008, Burmese Pythons in South Florida: Scientific support for invasive species management: Gainesville, University of Florida, p. 8.

Haskins, D.L., R.M. Gogal Jr., and T.D. Tuberville. 2019. Snakes as novel biomarkers of mercury contamination: a review. Reviews of Environmental Contamination and Toxicology 249:133-152. DOI: https://doi.org/10.1007/398_2019_26.   

Hunter, M.E., G. Meigs-Friend, J.A. Ferrante, B.J. Smith, and K.M. Hart. 2019. Efficacy of eDNA as an early detection indicator for Burmese pythons in the ARM Loxahatchee National Wildlife Refuge in the greater Everglades ecosystem. Ecological Indicators 102:617-622. DOI: https://doi.org/10.1016/j.ecolind.2019.02.058  

Krysko, K.L., K.M. Hart, B.J. Smith, T.H. Selby, M.S. Cherkiss, N.T. Coutu, R.M. Reichart, L.P. Nunez, F.J. Mazzotti, and R.W. Snow. 2012. Record length, mass, and clutch size in the nonindigenous Burmese Python, Python bivittatus Kuhl 1820 (Squamata: Pythonidae), in Florida. IRCF Reptiles & Amphibians 19(4):267-270.https://journals.ku.edu/reptilesandamphibians/article/view/13923. 

Mazzotti, F.J., M.S. Cherkiss ,K.M. Hart, R.W. Snow, M.R. Rochford, M.E. Dorcas, and R.N. Reed. 2011. Cold-induced mortality of invasive Burmese pythons in south Florida. Biological Invasions 13:143-151. DOI: https://doi.org/10.1007/s10530-010-9797-5. 

Mazzotti, F.J., S.A. Balaguera-Reina, L.A. Brandt, V. Briggs-González, M. Cherkiss, S. Farris, and A. Godahewa. 2022. Natural and anthropogenic factors influencing nesting ecology of the American Crocodile in Florida, United States. Frontiers in Ecology and Evolution 10(904576):1-14.

Mehrtens, J. M. Living Snakes of the World.  New York:  Sterling Publishing Company, Inc., 1987.

McCleery, R.A., A. Sovie, R.N. Reed, M.W. Cunningham, M.E. Hunter, and K.M. Hart. 2015. Marsh rabbit mortalities tie pythons to precipitous decline of mammals in the Everglades. Proceedings of the Royal Society B 282:1-7.DOI: http://dx.doi.org/10.1098/rspb.2015.0120. 

McCollister, M.F., J.M. Josimovich, A.L. Fitzgerald, D.K. Jansen, and A.F. Currylow. 2021. Native mammalian predators can depredate adult Burmese Pythons in Florida. Southeastern Naturalist 20(2):N55-N59.

Miller, M.A., J.M. Kinsella, R.W. Snow, M.M. Hayes, B.G. Falk, R.N. Reed, F.J. Mazzotti, C. Guyer, and C.M. Romagosa,. 2017. Parasite spillover: indirect effects of invasive Burmese Pythons. Ecology and Evolution 8:830-840. DOI: 10.1002/ece3.3557.  

Miller, M., Kirkland, M., and Ketterlin, J. 2019. Python Removal Programs. Everglades Cooperative Invasive Species Management Area. Available online at https://bugwoodcloud.org/mura/ECISMA/assets/File/summit19/4_2019_Summit_Python_Removal_Programs_SFWMD_FWC_NPS.pdf. Accessed on 03/29/2021.

National Park Service. 2009. Burmese python: species profile. Available online at http://www.nps.gov/ever/naturescience/burmesepython.htm. Last accessed 11/2/2009.
Pyron, R.A., Burbink, F.T., and Guiher, T.J. 2008. Claims of Potential Expansion throughout U.S. by Invasive Python Species Are Contradicted by Ecological Niche Models. PLoS ONE 3(8): e2931. DOI: doi:10.1371/journal.pone.0002931.

Reed, R. N. and G. H. Rodda. 2009. Giant constrictors: biological and management profiles and an establishment risk assessment for nine large species of pythons, anacondas and the Boa Constrictor. Open File Report 2009-1202, U.S. Dept. of the Interior, U.S. Geological Survey, Reston, Virginia. Available online at http://pubs.usgs.gov/of/2009/1202/pdf/OF09-1202.pdf.

Reed, R.N. and Snow, R.W. 2014. Assessing Risks to Humans from Invasive Burmese Pythons in Everglades National Park, Florida, USA. Wildlife Society Bulletin 38(2):366-369. DOI: 10.1002/wsb.413

Rodda, G.H., Jarnevich, C.S., and Reed, R.N. 2009. What parts of the US mainland are climactically suitable for invasive alien pythons spreading from Everglades National Park?. Biological Invasions 11: 241-252. DOI: 10.1007/s10530-008-9228-z.

Rodgers, L., Mason, C., Kirkland, M., Brown, R., Quincy, K., Metzger, E., Tipping, P., Miller, M., Mazzotti, F., Funck, S., Peters, A., Bohaty, C., and Laroche, F. 2021. Chapter 7: Status of Nonindigenous Species. 2021 South Florida Environmental Report DRAFT, Volume 1: 1-73.

Shwiff, S., Shwiff, S., Holderieath, J., Haden-Chomphosy, W., and Anderson, A. 2018. Economics of invasive species damage and damage management. Ecology and Management of terrestrial vertebrate invasive species in the United States. CRC Press, Boca Raton, FL. 403 pp, 35-59.

Smith, B.J., Rochford, M.R., Brien, M., Cherkiss, M.S., Mazzotti, F.J., Snow, S., and Hart, K.M. 2015. Largest Breeding Aggregation of Burmese Pythons (Python bivittatus) Kuhl 1820 (Squamata: Pythonidae) and Implications for Potential Development of a Control Tool. IRCF Reptiles & Amphibians 22(1): 16-19.

Smith, B.J., Cherkiss, M.S., Hart, K.M., Rochford, M.R., Selby, T.H., Snow, R.H., and Mazzotti, F.J. 2016. Betrayal: radio-tagged Burmese pythons reveal locations of conspecifics in Everglades National Park. Biological Invasions 18: 3239-3250. DOI: 10.1007/s10530-016-1211-5.

Smith, H.T., Sementelli, A., Meshaka, W.E., and Engeman, R.M. 2007. Reptilian pathogens of the Florida everglades: the associated costs of Burmese pythons. University of Michigan, School of Natural Resources. Accessed on 3/12/2021.

Snow, R. W., K. L. Krysko, K. M. Enge, L. Oberhofer, A. Warren-Bradley, and L. Wilkins. 2007b. Introduced populations of Boa constrictor (Boidae) and Python molurus bivitattus (Pythonidae) in southern Florida. pp. 416–438 in The Biology of Boas and Pythons, edited by R. W. Henderson and R. Powell. Eagle Mountain, UT: Eagle Mountain Publishing

Snow, R.W., Wolf, A.J., Greeves, B.W., Cherkiss, M.S., Hill, R., and Mazzotti, F.J. 2010. Thermoregulation by a Brooding Burmese Python (Python Molurus Bittivattus) In Florida. Southeastern Naturalist 9(2): 403-405. DOI: http://dx.doi.org/10.1656/058.009.0215

Solomon, L.K. 2019. Florida expands python fight; 1,000 apply to become hunters. Sun-Sentinel.com. Created on 9/13/2019. Accessed 3/31/2021.

Somaweera, R., Brien, M., and Shine, R. 2013. The Role of Predation in Shaping Crocodilian Natual History. Herpetological Monographs 27: 23-51. DOI: https://doi.org/10.1655/HERPMONOGRAPHS-D-11-00001

Walters, T.M., Mazzotti, F.J., and Fitz, C.H. 2016. Habitat Selection by the Invasive Species Burmese Python in Southern Florida. Journal of Herpetology 50(1): 50-56. DOI: https://doi.org/10.1670/14-098

Wilson, J.D. 2017. Indirect effects of invasive Burmese pythons on ecosystems in southern Florida. Journal of Applied Ecology 54: 1251-1258. DOI: 10.1111/1365-2664.

Wilson, J.D., Dorcas, M.E., and Snow, R.W. 2011. Identifying plausible scenarios for the establishment of invasive Burmese pythons (Python molurus) in Southern Florida. Biological Invasions 13: 1493-1504.

U.S. Fish & Wildlife Services. 2012b. The cost of invasive species. January 2012 Factsheet. https://www.fws.gov/home/feature/2012/pdfs/CostofInvasivesFactSheet.pdf. Accessed 3/11/2021.
 

Other Resources:
Burmese Python: Species Profile (National Park Service)

EDD Maps - Burmese python distribution in Florida

Giant Constrictors: Biological and Management Profiles and an Establishment Risk Assessment for Nine Large Species of Pythons, Anacondas, and the Boa Constrictor

What parts of the US mainland are climatically suitable for invasive alien pythons spreading from Everglades National Park?

USGS Research on Introduced Florida Snakes

Author: Campbell, G.M. & Freedman, J.A.

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.