Environmental Science and Pollution Research

, Volume 26, Issue 31, pp 31717–31729 | Cite as

Evaluating methods to detect and monitor populations of a large invasive lizard: the Argentine giant tegu

  • Richard M. EngemanEmail author
  • Bernard W. Kaiser
  • Kimberly J. Osorio
Research Article


The Argentine giant tegu, a large lizard native to South America, was first discovered as established in the USA in scrub habitats of west-central Florida in 2006. Invasive populations potentially could occupy an extensive range of habitats and in much of the southern United States and Mexico and threaten many native species. The Argentine giant tegu was recently deemed as having a “highest impact concern” among the invasive reptile species most threatening to Florida ecology. Among the most rewarding research directions identified for this species was “having a reliable and practical method to detect/monitor” them. We address this need by evaluating five methods for monitoring Argentine giant tegus on how well each method detected the species and whether the observations were sufficient to quantitatively assess population abundance using a widely applicable framework for indexing animal populations. Passive tracking plots were the most efficient and effective means for detecting tegus and calculating abundance indices but were best suited for late winter to spring before summer rains compacted tracking substrates. Gopher tortoise burrows are often used by tegus and camera traps on their entrances proved able to obtain data suitable for indexing populations but required more labor and expense than tracking plots. Trapping either at gopher tortoise burrows or along drift fences was ineffective at capturing tegus. Similarly, visual encounter transects were not effective for observing tegus.


Camera trap Drift fence Population index Tracking plot Trap testing Visual encounter survey 



This research was supported by the intramural research program of the U.S. Department of Agriculture; Hillsborough County Conservation and Environmental Lands Management Department; partial funding for this project was provided through Cooperative Agreement No. 40181AJ085 between Hillsborough County Conservation and Environmental Lands Management Department and the U.S. Fish and Wildlife Service.


  1. Allen BL, Allen LR, Engeman RM, Leung, LK.-P. (2014) Sympatric prey responses to lethal predator control: predator manipulation experiments. Front Zool 11:56Google Scholar
  2. Allen LR, Engeman RM (2015) Evaluating and validating abundance monitoring methods in absence of populations of known size. Environ Sci Pollut Res 22:2907–2915Google Scholar
  3. Allen BL, Allen LR, Engeman RM, Leung LK-P (2013) Intraguild relationships between sympatric predators exposed to lethal control: predator manipulation experiments. Front Zool 10:39Google Scholar
  4. Ashton PS, Ashton RE Jr (2004) The gopher tortoise: a life history. Pineapple Press, SarasotaGoogle Scholar
  5. Avery ML, Tillman EA, Krysko KL (2009) Gopherus polyphemus (gopher tortoise), Ctenosaura similis (Gray’s spiny-tailed iguana). Predation Herpetol Rev 40:435Google Scholar
  6. Avery ML, Humphrey J, Engeman RM (2016) Evaluating trap alternatives for removal of black and white tegus Salvator merianae. Southeast Nat 15:107–113Google Scholar
  7. Baldwin RA, Quinn N, Davis DH, Engeman RM. (2014) Effectiveness of rodenticides for managing invasive roof rats and native deer mice control in orchards. Environ Sci Pollut Res 21:5795–5802Google Scholar
  8. Balsai M (1998) Tegus: South America’s cunning teiids. Reptiles 6(9):52–69Google Scholar
  9. Bartlett RD, Bartlett PP (1999) A field guide to Florida reptiles and amphibians. Gulf Publishing Co., HoustonGoogle Scholar
  10. Caughley G (1977) Analysis of vertebrate populations. Wiley, New YorkGoogle Scholar
  11. Corn ML, Buck EH, Rawson J, Segarra A, Fischer E (2002) Invasive non-native species: background and issues for Congress. Congressional Research Service and The Library of Congress, Washington, DCGoogle Scholar
  12. Cope ED. (1875) Check-list of North-American Batrachia and Reptilia. Bulletin of the United States National Museum 1:1–104Google Scholar
  13. Enge KM (2007) FWC bioprofile for the Argentine black and white tegu (Tupinambis merianae). Florida Fish and Wildlife Conservation Commission report, TallahasseeGoogle Scholar
  14. Enge KM, Kaiser BW, Dickerson RB. (2006) Another large exotic lizard in Florida, the Argentine black and white tegu. In: Proceedings of the 28th Annual Gopher Tortoise Council Meeting. Gopher Tortoise Council, Valdosta, Georgia NpnGoogle Scholar
  15. Engeman RM (2005) A methodological and analytical paradigm for indexing animal populations applicable to many species and observation methods. Wildl Res 32:203–210Google Scholar
  16. Engeman R, Allen LR (2000) Overview of a passive tracking index for monitoring wild canids and associated species. Integr Pest Manag Rev 5:197–203Google Scholar
  17. Engeman RM, Avery ML (2016) Prioritizing management and research actions against invasive reptiles in Florida: a collaboration by an expert panel. Herp Alliance and USDA/WS/National Wildlife Research Center, Fort CollinsGoogle Scholar
  18. Engeman RM, Pipas MJ, Gruver KS, Allen L (2000) Monitoring coyote populations with a passive activity index. Wildl Res 27:553–557Google Scholar
  19. Engeman RM, Massei G, Sage M, Gentle M. (2013) Monitoring wild pig populations: a review of methods. Environ Sci Pollut Res 20:8077–8091Google Scholar
  20. Engeman RM, Constantin BU, Nelson M, Woolard J, Bourassa J (2001) Monitoring changes in feral swine population and spatial distribution of activity. Environ Conserv 28:235–240Google Scholar
  21. Engeman RM, Woolard JW, Perry ND, Witmer G, Hardin S, Brashears L, Smith HT, Muiznieks B, Constantin BU (2006) Rapid assessment for a new invasive species threat: the case of the Gambian giant pouched rat in Florida. Wildl Res 33:439–448Google Scholar
  22. Engeman RM, Stevens A, Allen J, Dunlap J, Daniel M, Teague D, Constantin BU (2007) Feral swine management for conservation of an imperiled wetland habitat: Florida’s vanishing seepage slopes. Biol Conserv 134:440–446Google Scholar
  23. Engeman RM, Constantin BU, Hardin S, Smith HT, Meshaka WE Jr (2009a) “Species pollution” in Florida: a cross-section of invasive vertebrate issues and management responses. In: Wilcox CP, Turpin RB (eds) Invasive species: detection, impact and control. Nova Science Publishers, Hauppauge, pp 179–197Google Scholar
  24. Engeman RM, Kennedy M, Constantin BU, Christie ML, Hall PT (2009b) Ctenosaura similis (black spinytail iguana), Gopherus polyphemus. (gopher tortoise) concurrent burrow use. Herpetol Rev 40:84Google Scholar
  25. Engeman RM, Jacobson E, Avery M, Meshaka WE Jr (2011) The aggressive invasion of exotic reptiles in Florida with a focus on prominent species: a review. Curr Zool 57:599–612Google Scholar
  26. Engeman RM, Allen BL, Allen LR (2017) Study design concepts for inferring functional roles of mammalian top predators. Special issue on “Strengths, weaknesses, opportunities and threats to the study and conservation of top-predators and their role in terrestrial food webs”. Food Webs 12:56–63Google Scholar
  27. FNAI (Florida Natural Areas Inventory) (2010) Guide to the natural communities of Florida. Florida Natural Areas Inventory and Florida Department of Natural Resources, TallahasseeGoogle Scholar
  28. Franzetti B, Ronchi B, Marini F, Scacco M, Calmanti R, Calabrese A, Paola A, Paolo M, Focardi S (2012) Nocturnal line transect sampling of wild boar (Sus scrofa) in a Mediterranean forest: long-term comparison with capture–mark–resight population estimates. Eur J Wildl Res 58:385–402Google Scholar
  29. FWC (Florida Fish and Wildlife Conservation Commission) (2015) Tegus in Florida. In: Florida Fish and Wildlife Conservation Commission. FL, TallahasseeGoogle Scholar
  30. Galetti M, Bovendorp RS, Fadin RF, Gussoni COA, Rodrigues M, Alvarez AD, Guimaraes PR, Alves K (2009) Hyper-abundant mesopredators and bird extinction in an Atlantic forest island. Zoolog 26:288–298Google Scholar
  31. Hardin S (2007) Managing non-native wildlife in Florida: state perspective, policy and practice. In: Witmer G, Pitt W, Fagerstone K (eds) Managing Vertebrate Invasive Species: Proceedings of an International Symposium. USDA/APHIS/WS, National Wildlife Research Center, Fort Collins, pp 43–52Google Scholar
  32. Hare KM (2012) Herpetofauna: systematic searches v1.0. Inventory and monitoring toolbox: herpetofauna. Department of Conservation, WellingtonGoogle Scholar
  33. Jackson JA, Jackson BJS (2007) An apparent mutualistic association between invasive exotics: Brazilian pepper (Schinus terebinthifolius) and black spiny-tailed iguanas (Ctenosaura similis). Nat Areas J 27:254–257Google Scholar
  34. Jarnevich CS., Hayes MA, Fitzgerald LA, Yackel Adams AA, Falk BG, Collier MAM, Bonewell LR, Klug PE, Naretto S, Reed RN. (2018) Modeling the distributions of tegu lizards in native and potential invasive ranges. Scientific Reports. Online firstGoogle Scholar
  35. Johnson SA, McGarrity M (2017) Florida invader: tegu lizard. University of Florida/IFAS Extension, GainesvilleGoogle Scholar
  36. Kaiser BW, Osorio KJ, Enge KM, Engeman RM (2013) Tupinambis merianae (Argentine giant tegu), Pantherophis gutattatus guttatus (red rat snake). Nonpredatory killing SSAR. Herpetol Rev 44:329Google Scholar
  37. King D, Green B, Herrera E (1994) Thermoregulation in a large teiid lizard, Tupinambis teguixin, in Venezuela. Copeia 1994:806–808Google Scholar
  38. Krebs CJ (1998) Ecological methodology. Benjamin/Cummings, Menlo ParkGoogle Scholar
  39. Lambert MRK (2002) Amphibians and reptiles. In: Grant IF, Tingle CCD (eds) Ecological monitoring methods for the assessment of pesticide impact in the tropics. Natural Resources Institute, Chatham, pp 213–227Google Scholar
  40. Lopes HR, Abe AS. (1999) Biologia reprodutivo e comportamento do teiú, Tupinambis merianae, em cativeiro (Reptilia, Teiidae). In: Fang TG, Montenegro OL, Bodme RE (Eds.). Manejo y Conservación de Fauna Silvestre en América Latina. Instituto de Ecología, La Paz, Bolivia. pp 259–272Google Scholar
  41. Luxmoore R, Groombridge B, Broads S (eds) (1988) Significant Trade in wildlife: a review of selected species in CITES Appendix II. Volume 2: Reptiles and invertebrates. IUCN Conservation Monitoring Centre, CambridgeGoogle Scholar
  42. McEachern MA, Yackel Adams AA, Klug PE, Fitzgerald LA, Reed RN (2015) Brumation of introduced black and white tegus, Tupinambis merianae (Squamata: Teiidae), in Southern Florida. Southeast Nat 14(2):319–328Google Scholar
  43. Mercolli C, Yanosky A (1994) The diet of adult Tupinambis teguixin (Sauria: Teiidae) in the eastern chaco of Argentina. Herpetol J 4:15–19Google Scholar
  44. Meshaka WE Jr, Butterfield BP, Hauge JB (2004) The exotic amphibians and reptiles of Florida. Krieger Publishing Company, MalabarGoogle Scholar
  45. Meshaka WE Jr, Smith HT, Engeman RM, Dean CL, Moore JA, O’Brien WE (2005) The geographically contiguous and expanding range of the northern curlytail lizard (Leicephalus carinatus armouri) in Florida. Southeast Nat 4:521–526Google Scholar
  46. Meshaka WE Jr (2011) Runaway train in the making: the exotic amphibians, reptiles, turtles, and crocodilians of Florida. Monograph 1. Herpetol Conserv Biol 6:1–101Google Scholar
  47. Ryan DA, Heywood A (2003) Improving the precision of longitudinal ecological surveys using precisely defined observational units. Environmetrics 14:83–293Google Scholar
  48. SFWMD (South Florida Water Management District) (2008) Executive Summary 2008 South Florida Environmental Report. South Florida Water Management District, West Palm BeachGoogle Scholar
  49. U.S. Congress (1993) Harmful non indigenous species in the United States. Office of Technology Assessment, OTA F 565 Government Printing Office, Washington DCGoogle Scholar
  50. Vitt LJ (1995) The ecology of tropical lizards in the Caatinga of Northeast Brazil. Occasional Papers of the Oklahoma Museum of. Nat Hist 1:1–29Google Scholar

Copyright information

© This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply 2019

Authors and Affiliations

  • Richard M. Engeman
    • 1
    Email author
  • Bernard W. Kaiser
    • 2
  • Kimberly J. Osorio
    • 2
  1. 1.National Wildlife Research CenterFort CollinsUSA
  2. 2.Hillsborough Parks, Recreation and Conservation DepartmentRiverviewUSA

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