Betrayal: radio-tagged Burmese pythons reveal locations of conspecifics in Everglades National Park

The “Judas” technique is based on the idea that a radio-tagged individual can be used to “betray” conspecifics during the course of its routine social behavior. The Burmese python (Python bivittatus) is an invasive constrictor in southern Florida, and few methods are available for its control. Pythons are normally solitary, but from December–April in southern Florida, they form breeding aggregations containing up to 8 individuals, providing an opportunity to apply the technique. We radio-tracked 25 individual adult pythons of both sexes during the breeding season from 2007–2012. Our goals were to (1) characterize python movements and determine habitat selection for betrayal events, (2) quantify betrayal rates of Judas pythons, and (3) compare the efficacy of this tool with current tools for capturing pythons, both in terms of cost per python removed (CPP) and catch per unit effort (CPUE). In a total of 33 python-seasons, we had 8 betrayal events (24 %) in which a Judas python led us to new pythons. Betrayal events occurred more frequently in lowland forest (including tree islands) than would be expected by chance alone. These 8 events resulted in the capture of 14 new individuals (1–4 new pythons per event). Our effort comparison shows that while the Judas technique is more costly than road cruising surveys per python removed, the Judas technique yields more large, reproductive females and is effective at a time of year that road cruising is not, making it a potential complement to the status quo removal effort.

[1]  C. Donlan,et al.  Bio-Economics of Large-Scale Eradication of Feral Goats From Santiago Island, Galápagos , 2009 .

[2]  Donlan,et al.  Eradication of feral goats Capra hircus from Pinta Island, Galápagos, Ecuador , 2004, Oryx.

[3]  F. Wall.  Ophidia Taprobanica: Or the Snakes of Ceylon , 2011 .

[4]  R. Whitaker,et al.  Snakes of India: The Field Guide , 2016 .

[5]  Gordon H. Rodda,et al.  Giant Constrictors: Biological and Management Profiles and an Establishment Risk Assessment for Nine Large Species of Pythons, Anacondas, and the Boa Constrictor , 2009 .

[6]  S. Harris,et al.  Turning the tide: The eradication of invasive species , 2002 .

[7]  Gordon H. Rodda,et al.  Problem snake management : the habu and the brown treesnake , 2000 .

[8]  R. Reed,et al.  Invasive reptiles and amphibians: global perspectives and local solutions , 2010 .

[9]  D. Pimental.  ENVIRONMENTAL AND ECONOMIC COSTS OF VERTEBRATE SPECIES INVASIONS INTO THE UNITED STATES , 2007 .

[10]  B. Coblentz,et al.  Restoration of Insular Ecosystems: Control of Feral Goats on Aldabra Atoll, Republic of Seychelles , 1999, Biological Invasions.

[11]  K. Rose,et al.  Genetic relationships within social groups influence the application of the Judas technique: A case study with wild dromedary camels , 2015 .

[12]  J. Willson,et al.  Python molurus bivittatus (Burmese python). Minimum size at maturity , 2014 .

[13]  J. Mcilroy,et al.  The 'Judas' Pig Technique: a Method that Could Enhance Control Programmes against Feral Pigs, Sus scrofa , 1997 .

[14]  H. Erasmus,et al.  CAPTIVE BREEDING OF PYTHONS IN SOUTH AFRICA, INCLUDING DETAILS OF AN INTERSPECIFIC HYBRID (PYTHON SEBAE NATALENSIS X PYTHON MOL UR US BIVIITA TUS) , 1984 .

[15]  Kristen M. Hart,et al.  Cold-induced mortality of invasive Burmese pythons in south Florida , 2010, Biological Invasions.

[16]  R. Snow,et al.  Dietary habits of the Burmese python, Python molurus bivittatus, in Everglades National Park, Florida , 2007 .

[17]  H. Moldenke,et al.  The natural features of southern Florida, especially the vegetation, and the Everglades , 1943 .

[18]  G. Perry.  Venomous takeovers: Problem Snake Management: The Habu and the Brown Treesnake edited by G.H. Rodda, Y. Sawai, D. Chiszar and H. Tanaka , 1999 .

[19]  C. Donlan,et al.  Increasing the efficacy of Judas goats by sterilisation and pregnancy termination , 2005 .

[20]  J. Beeuwkes,et al.  Introduction and control of three invasive mosquito species in the Netherlands, July-October 2010. , 2010, Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin.

[21]  Kristen M. Hart,et al.  A field test of attractant traps for invasive Burmese pythons (Python molurus bivittatus) in southern Florida , 2011 .

[22]  E. Zhao,et al.  Herpetology of China , 1993 .

[23]  W. E. Meshaka,et al.  An annotated inventory of the herpetofauna of Everglades National Park, Florida , 2000 .

[24]  P. Bajer,et al.  Using the Judas technique to locate and remove wintertime aggregations of invasive common carp , 2011 .

[25]  Dan Taylor,et al.  RADIO TELEMETRY AS AN AID IN ERADICATING , 1988 .

[26]  Michael C. Granatosky,et al.  Verified non-indigenous amphibians and reptiles in Florida from 1863 through 2010: Outlining the invasion process and identifying invasion pathways and stages , 2011 .

[27]  Brian J. Smith,et al.  Environmental DNA (eDNA) Sampling Improves Occurrence and Detection Estimates of Invasive Burmese Pythons , 2015, PloS one.

[28]  Kristen M. Hart,et al.  Marsh rabbit mortalities tie pythons to the precipitous decline of mammals in the Everglades , 2015, Proceedings of the Royal Society B: Biological Sciences.

[29]  J. Macmahon,et al.  The Giant Snakes. , 1962 .

[30]  D. H. Vuren,et al.  A Test of the Judas Technique as a Method for Eradicating Feral Pigs , 2004 .

[31]  B. Groombridge,et al.  Pythons in South-east Asia : a review of distribution, status, and trade in three selected species , 1991 .

[32]  G. Nugent,et al.  Assessing the Effectiveness of Tuberculosis Management in Brushtail Possums (Trichosurus vulpecula), through Indirect Surveillance of Mycobacterium bovis Infection Using Released Sentinel Pigs , 2014, Veterinary medicine international.

[33]  K. Rose,et al.  Can the Judas technique be applied to pest birds , 2006 .

[34]  Richard M. Engeman,et al.  Objectives and Integrated Approaches for the Control of Brown Tree Snakes , 2001 .

[35]  Christina M. Romagosa,et al.  Severe mammal declines coincide with proliferation of invasive Burmese pythons in Everglades National Park , 2012, Proceedings of the National Academy of Sciences.

[36]  C. Donlan,et al.  Archipelago-Wide Island Restoration in the Galápagos Islands: Reducing Costs of Invasive Mammal Eradication Programs and Reinvasion Risk , 2011, PloS one.

[37]  Michael E. Dorcas,et al.  Identifying plausible scenarios for the establishment of invasive Burmese pythons (Python molurus) in Southern Florida , 2011, Biological Invasions.

[38]  R Core Team,et al.  R: A language and environment for statistical computing. , 2014 .

[39]  F. Kraus,et al.  Alien reptiles and amphibians : a scientific compendium and analysis , 2009 .

[40]  Ikuko Fujisaki,et al.  Home range, habitat use, and movement patterns of non-native Burmese pythons in Everglades National Park, Florida, USA , 2015, Animal Biotelemetry.

[41]  J. Menzies,et al.  Alien Reptiles and Amphibians: A Scientific Compendium and Analysis. , 2009 .

[42]  K. Kettenring,et al.  Lessons learned from invasive plant control experiments: a systematic review and meta‐analysis , 2011 .

[43]  R. Snow,et al.  Birds Consumed by the Invasive Burmese Python (Python molurus bivittatus) in Everglades National Park, Florida, USA , 2011 .

[44]  D. Garcelon,et al.  Eradication of Feral Pigs From Pinnacles National Monument , 2008 .

[45]  Brian J. Smith,et al.  Record length, mass, and clutch size in the nonindigenous Burmese Python, Python bivittatus Kuhl 1820 (Squamata: Pythonidae), in Florida , 2012 .