Biological Invasions

, Volume 13, Issue 7, pp 1493–1504 | Cite as

Identifying plausible scenarios for the establishment of invasive Burmese pythons (Python molurus) in Southern Florida

  • John D. Willson
  • Michael E. Dorcas
  • Raymond W. Snow
Original Paper


Successful invasions of secretive alien species often go unrecognized until spread has exceeded the point where control or eradication is feasible. In such situations, understanding factors that contributed to establishment can be critical to preventing subsequent introductions of previously-successful invaders or ecologically similar species. The Burmese python (Python molurus bivittatus), a native to Southeast Asia, is abundant in the pet trade and is now well-established in southern Florida. Although there can be little argument that the ultimate source of Florida pythons was the pet industry, there has been limited consideration of biological support for scenarios that may have lead to their establishment. In this study we use information on python capture rates and biologically-derived population growth models to evaluate the plausibility of various scenarios for python establishment. Our results indicate that scenarios involving relatively recent establishment (post-1990) require large numbers (100–1,000) of founders or unrealistically high juvenile survivorship. Intentional simultaneous release of large numbers of pythons is unlikely and accidental release of large numbers of founders is inconsistent with the spatial and temporal pattern of pythons captures in the region. We conclude that the most parsimonious scenario for establishment of pythons in Florida involves the release of a relatively small number of founders prior to 1985. Our results demonstrate that for pythons and other species with low inherent detection probabilities, early action during incipient phases of an invasion is critical and understanding likely introduction scenarios is important for preventing similar situations from occurring elsewhere or with other species.


Everglades National Park Introduction Invasive species Population growth Python molurus bivittatus Reptiles Snakes 



We thank numerous people who collected python abundance and life-history data in Florida, without which these modeling exercises would not have been possible. Of particular note for their involvement in field collection and data collection for pythons are Matt Brien, Michael Cherkiss, Justin Davis, Anthony Flanagan, Wellington Guzman, Kristen Hart, Bobby Hill, Toren Hill, Frank Mazzotti, Kenneth Rice, Michael Rochford, LeRoy Rodgers, Theresa Walters, and Alex Wolf. Discussions with Kenneth Krysko, Robert Reed, and Paul Andreadis were useful in evaluating the spatial and temporal patterns of python captures. Kristen Hart, Shannon Pittman, Steven Price, Robert Reed, J. W. Gibbons, and one anonymous reviewer provided comments that helped to improve the manuscript. Partial funding for this study was provided by USGS, Davidson College Biology Department, and by National Science Foundation grant (DEB-0,347,326) to M.E. Dorcas. This material is based upon work supported by the Department of Energy under Award Number DE-FC-09-075R22506.


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Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • John D. Willson
    • 1
    • 4
  • Michael E. Dorcas
    • 2
  • Raymond W. Snow
    • 3
  1. 1.Savannah River Ecology LaboratoryPO Drawer EAikenUSA
  2. 2.Department of BiologyDavidson CollegeDavidsonUSA
  3. 3.Everglades National ParkHomesteadUSA
  4. 4.Department of Fisheries and Wildlife SciencesVirginia Polytechnic Institute and State UniversityBlacksburgUSA

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