Modeling relative habitat suitability of southern Florida for invasive Burmese pythons (Python molurus bivittatus)
Invasive Burmese pythons are altering the ecology of southern Florida and their distribution is expanding northward. Understanding their habitat use is an important step in understanding the pathways of the invasion.
This study identifies key landscape variables in predicting relative habitat suitability for pythons at the present stage of invasion through presence-only ecological niche modeling using geographical sampling bias correction.
We used 2014 presence-only observations from the EDDMapS database and three landscape variables to model habitat suitability: fine-scale land cover, home range-level land cover, and distance to open freshwater or wetland. Ten geographical sampling bias correction scenarios based on road presence and sampling effort were evaluated to improve the efficacy of modeling.
The best performing models treated road presence as a binary factor rather than a continuous decrease in sampling effort with distance from roads. Home range-level cover contributed the most to the final prediction, followed by proximity to water and fine-scale land cover. Estuarine habitat and freshwater wetlands were the most important variables to contribute to python habitat suitability at both the home range-level and fine-scale. Suitability was highest within 30 m of open freshwater and wetlands.
This study provides quantifiable, predictive relationships between habitat types and python presence at the current stage of invasion. This knowledge can elucidate future targeted studies of python habitat use and behavior and help inform management efforts. Furthermore, it illustrates how estimates of relative habitat suitability derived from MaxEnt can be improved by both multi-scale perspectives on habitat and consideration of a variety of bias correction scenarios for selecting background points.
KeywordsBurmese pythons Ecological niche modeling Invasive species Landscape-level habitat MaxEnt Python molurus bivittatus Southern Florida
We thank R. Snow, C. Bargeron, P. Andreadis, I. Bartoszek, and C. Ervin for providing data and insight into the development of the model. We thank J.D. Willson and S. Fei for comments that greatly improved this manuscript. This work was partially funded by a Purdue University Knox Fellowship grant to H. Mutascio and the National Science Foundation Postdoctoral Fellowship in Biology Program Grant No. 1309144. We also thank The McIntire-Stennis Cooperative Forestry Research Program for their financial support.
- Andreadis PT (2011) Python molrus bivittatus (Burmese python). Reproducing population. Herpetol Rev 42(2):302–303Google Scholar
- Barve N (2008) Tool for partial-ROC (Version 1) (Software). http://kuscholarworks.ku.edu/dspace/handle/1808/10059
- Beyer HL (2012) Geospatial Modelling Environment (Version 0.7.3.0) (Software). http://www.spatialecology.com/gme
- Bhupathy S, Vuayan VS (1989) Status, distribution and general ecology of the Indian python, Python molurus molurus linn. in Keoladeo National Park, Bharatpur, Rajasthan. J Bombay Nat Hist Soc 86(3):381–387Google Scholar
- Conservancy of Southwest Florida (2015) Burmese pythons. https://www.conservancy.org/our-work/science/burmese-pythons. Accessed Feb 2016
- Dorcas ME, Willson JD (2013) Hidden giants: problems associated with studying secretive invasive pythons. In: Lutterschmidt WI (ed) Reptiles in research: investigations of ecology, physiology, and behavior from desert to sea. Nova Biomedical, New York, pp 367–385Google Scholar
- Dorcas ME, Willson JD, Reed RN, Snow RW, Rochford MR, Miller MA, Meshaka WE Jr, Andreadis PT, Mazzotti FJ, Romagosa CM, Hart KM (2012) Severe mammal declines coincide with proliferation of invasive Burmese pythons in Everglades National Park. Proc Natl Acad Sci USA 109(7):2418–2422CrossRefPubMedPubMedCentralGoogle Scholar
- EDDMapS (2015) Early detection & distribution mapping system. The University of Georgia—Center for invasive species and ecosystem health. http://www.eddmaps.org/. Accessed Feb 2015
- Ernst CH, Zug GR (1996) Snakes in question. Smithsonian Institution Press, Washington, DCGoogle Scholar
- Greene DU, Potts JM, Duquesnel JG, Snow RW (2007) Geographic distribution: Python molurus bivittatus (Burmese python). Herpetol Rev 38:355Google Scholar
- Hart KM, Cherkiss MS, Smith BJ, Mazzotti FJ, Fujisaki I, Snow RW, Dorcas ME (2015) Home range, habitat use, and movement patterns of non-native Burmese pythons in Everglades National Park, Florida, USA. Anim Biotelem 3(8):1–13Google Scholar
- Harvey RG, Brien ML, Cherkiss MS, Dorcas M, Rochford M, Snow RW, Mazzotti FJ (2009) Burmese pythons in south Florida: scientific support for invasive species management. Wildlife Ecology and Conservation Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USAGoogle Scholar
- Kramer-Schadt S, Niedballa J, Pilgrim JD, Schröder B, Lindenborn J, Reinfelder V, Stillfried M, Heckmann I, Scharf AK, Augeri DM, Cheyne SM, Hearn AJ, Ross J, Macdonald DW, Mathai J, Eaton J, Marshall AJ, Semiadi G, Rustam R, Bernard H, Alfred R, Samegima H, Duckworth JW, Breitenmoser-Wuersten C, Belant JL, Hofer H, Wilting A (2013) The importance of correcting for sampling bias in MaxEnt species distribution models. Divers Distrib 19(11):1366–1379CrossRefGoogle Scholar
- Krausman PR (1999) Some basic principles of habitat use. Grazing Behavior of Livestock and Wildlife, Idaho Forest, Wildlife & Range Exp. Sta. Bull.#70, University of Idaho, Moscow, ID, pp 85–90Google Scholar
- Meshaka WE Jr, Loftus WF, Steiner T (2000) The herpetofauna of Everglades National Park. Fla Sci 63(2):84–103Google Scholar
- Metzger CJ (2013) Python molurus bivittatus (Burmese python): habitat use. Herpetol Rev 44:333–334Google Scholar
- Minton SA (1966) A contribution to the herpetology of West Pakistan. Bull Am Mus Nat Hist 134:29–184Google Scholar
- Mladenoff DJ, Clayton MK, Pratt SD, Sickley TA, Wydeven AP (2009) Change in occupied wolf habitat in the northern Great Lakes region. In: Wydeven AP, van Deelen TR, Heske AJ (eds) Recovery of Gray wolves in the Great Lakes region of the United States. Springer, New York, pp 119–138CrossRefGoogle Scholar
- Peterson AT (2011) Ecological niches and geographic distributions (MPB-49). Princeton University Press, PrincetonGoogle Scholar
- Phillips SJ, Dudík M, Schapire RE (2004) A maximum entropy approach to species distribution modeling. In: Proceedings of the Twenty-First International Conference on Machine Learning, pp 655–662Google Scholar
- R Development Core Team (2011) R: a language and environment for statistical computing. R Foundation for Statistical Computing, ViennaGoogle Scholar
- Reed RN, Krysko KL, Snow RW, Rodda GH (2010) Is the Northern African python (Python sebae) established in southern Florida? IRCF Reptile Amphib 17(1):52–54Google Scholar
- Snow RW, Brien ML, Cherkiss MS, Wilkins L, Mazzotti FJ (2007a) Dietary habits of the Burmese python, Python molurus bivittatus, in Everglades National Park, Florida. Herpetol Bull 101:5–7Google Scholar
- Snow RW, Krysko KL, Enge KM, Oberhofer L, Warren-Bradley A, Wilkins L (2007b) Introduced populations of Boa constrictor (Boidae) and Python molurus bivittatus (Pythonidae) in southern Florida. In: Henderson RW, Powell R (eds) Biology of the Boas and Pythons. Eagle Mountain Publishing, Eagle Mountain, pp 416–438Google Scholar
- Warren DL, Glor RE, Turelli M (2010) ENMTools: a toolbox for comparative studies of environmental niche models. Ecography 33(3):607–611Google Scholar
- Whitaker R (1978) Common Indian snakes: a field guide. Macmillan India, DelhiGoogle Scholar
- Wilting A, Cord A, Hearn AJ, Hesse D, Mohamed A, Traeholdt C, Cheyne SM, Sunarto S, Jayasilan M-A, Ross J, Shapiro AC, Sebastian A, Dech S, Breitenmoser C, Sanderson J, Duckworth JW, Hofer H (2010) Modelling the species distribution of flat-headed cats (Prionailurus planiceps), an endangered South-East Asian small felid. PLoS ONE 5(3):e9612CrossRefPubMedPubMedCentralGoogle Scholar