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First Observations of Nesting by the Argentine Black and White Tegu, Tupinambis merianae, in South Florida
Tony Pernas, Dennis J. Giardina, Alan McKinley, Aaron Parns, and Frank J. Mazzotti

Southeastern Naturalist, Volume 11, Issue 4 (2012): 765–770

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2012 SOUTHEASTERN NATURALIST 11(4):765–770 First Observations of Nesting by the Argentine Black and White Tegu, Tupinambis merianae, in South Florida Tony Pernas1, Dennis J. Giardina2, Alan McKinley1, Aaron Parns1, and Frank J. Mazzotti3,* Abstract - Florida has the most species of introduced and established reptiles in the world. There are more species of non-native lizards reproducing in Florida than native species. Tupinambis merianae (Argentine Black and White Tegu) is established in parts of Hillsborough and Polk counties, FL. No evidence of reproduction has been published in other areas of Florida, although this species has been sighted in various other Florida locations, especially in southeastern sites. Using radio-telemetry, we tracked an adult female tegu in Miami-Dade County to a ruderal thicket with a suspected nest mound. Upon excavation of the mound, we found one clutch of 21 eggs from the current year, and one clutch of 22 hatched egg shells and 13 unhatched eggs from a past year. This is the first evidence confirming expansion of a reproducing population of Argentine Black and White Tegus into southeastern Florida. If this population is small and localized, there is potential for removal if swift, decisive action is taken. Introduction Non-native invasive species are a major threat to ecological integrity and biological diversity (Parker et al. 1999, Wilcove et al. 1998). Increasing attention is being paid to non-native amphibians and reptiles (Bomford et al. 2009, Kraus 2009, Meshaka 2008, Phillips et al. 2003), especially in Florida where 3 recent papers have described the current invasion by reptiles and amphibians as “aggressive” and “a runaway train” (Engeman et al. 2011, Krysko et al. 2011a, Meshaka 2011). South Florida has proven to be particularly vulnerable to invasion by reptiles because it has a subtropical climate, a disturbed natural environment that provides suitable habitats for invasive species (ponds, canals, and levees), and major sources of non-native species from the pet trade (port of entry, captive breeders, and animal dealers) (Butterfield et al. 1997, Wilson and Porras 1983). As a result, Florida currently has more species of introduced and established reptiles than any other state, and the rate of accumulation of new species is increasing rapidly (Krysko et al. 2011a, b; Meshaka 2011). There are more species of non-native lizards reproducing in Florida than native species. The 4 largest lizards breeding in Florida are from Africa, South America, and Central America (Engeman et al. 2011). A population of Tupinambis merianae Duméril and Bibron (Argentine Black and White Tegu) exists in parts of Hillsborough and Polk counties in west-central Florida (Enge 2007, Krysko et al. 2011b). Argentine Black and White Tegus are omnivorous and primarily terrestrial, although they are good swimmers (Achaval 1977, Cei 1986). 1National Park Service, Biological Resources Management Division, Florida/Caribbean Exotic Plant Management Team, 18001 Old Cutler Road, Suite 419, Palmetto Bay, FL 33157-6422. 2Florida Fish and Wildlife Conservation Commission, Rookery Bay NERR, 300 Tower Road, Naples, FL 34113. 3University of Florida, 3205 College Avenue, Davie, FL 33314. *Corresponding author - 766 Southeastern Naturalist Vol. 11, No. 4 The Argentine Black and White Tegu is an active burrower and spends a lot of time in burrows to avoid extremes in temperature (Abe 1995, Andrade and Abe 1999). In addition to their breeding population, Argentine Black and White Tegus have been sighted in various locations elsewhere in Florida, especially in Miami- Dade County in southeastern Florida (Engeman et al. 2011, Krysko et al. 2011b). However, no evidence has been published for reproduction. Here, we report the first observations of nesting of the Argentine Black and White Tegu in southeastern Florida. Methods and Results In response to numerous observations of Argentine Black and White Tegus in southern Miami-Dade County, partners of the Everglades Cooperative Invasive Species Management Area (ECISMA) began an assessment of the status of a potential population. This assessment included reconnaissance surveys by vehicle and foot, camera trapping, live trapping, and radio telemetry of tegus. In 2010, 17 live traps were deployed at various locations in Florida City, Miami-Dade County, including one at the Miami-Dade Juvenile Residential Facility (25°22.3'N, 80°28.9'W), using fresh chicken eggs as bait. Trapping was initiated on 27 April and concluded on 27 September. Traps were opened and checked daily from Monday through Friday and were closed on the weekends, for a total of 1849 trap nights (109 trap nights at the Miami-Dade Juvenile Residential Facility). We trapped a total of 124 Argentine Tegus. On 9 September 2010, we collected a female Argentine Tegu at the Miami-Dade Juvenile Residential Facility in a live trap. We surgically implanted a VHF radio transmitter on 30 September 2010, and the female was released at the residential facility on 4 October 2010. A total of 36 radio-telemetry locations were recorded between 4 October 2010 and 7 June 2011 when the female was recaptured in a live trap. Sixteen locations were within a ruderal thicket dominated by invasive exotic plants on the western side of the residential facility, and upon investigation, a nest mound was discovered in the thicket (25°22.389'N, 80°28.924'W). The habitat surrounding the Miami-Dade Juvenile Detention Center is disturbed short-hydroperiod marl prairie consisting of a mixture of wet prairie, Cladium jamaicense Crantz (Sawgrass), tree islands, and tropical hammock plant communities. The detention center facility and fenced grounds is constructed on approximately 20 acres of limestone fill. The majority of the detention center’s land is maintained by regular mowing. The northern perimeter of the detention center is unmaintained and, as a result of substrate disturbance, was heavily colonized by invasive exotic species such as Schinus terabinthafolius Raddi (Brazilian Pepper), Leucaena leucocephala (Lam.) deWit (Lead Tree), Albizia lebbeck (L.) Benth (Woman’s Tongue), Ricinus communis L. (Castor Bean), and Nephrolepis cordifolia (L.) K. Presl (Sword Fern). Native species present were typical of disturbed sites and included Salix spp. (willow), Baccharis halimifolia L. (Eastern Baccharia), Bidens alba L. (Shephard’s Needles), and Lippia nodiflora L. (Frog Fruit). The nest mound was composed of discarded potting soil, decomposed organic material, and detritus at the base of a Lead Tree stump covered by Syngonium podophyllum Schott (Arrowhead Vine), a non-native invasive species (Fig. 1). The nest mound was located approximately 7 m west of the eastern edge of the 2012 T. Pernas, D.J. Giardina, A. McKinley, A. Parns, and F.J. Mazzotti 767 Figure 1. Nest mound (top) and excavated nest (bottom) of the telemetered Argentine Black and White Tegu at the Miami-Dade Juvenile Residential Facility. Nest was located at the base of a Lead Tree stump. 768 Southeastern Naturalist Vol. 11, No. 4 thicket. On 9 June 2011, we excavated the suspected nest mound (203 cm x 152 cm x 61 cm) by removing vines and systematically dismantling it using hand tools (Fig. 1). We uncovered a nest chamber (33 cm x 23 cm x 15 cm) in the approximate center of the mound, containing a clutch of 21 eggs at a depth (to top of clutch) of 41 cm. During excavation, 2 eggs were damaged and 1 was opened to verify the species and to estimate age of development. The remaining 18 eggs were collected. A second, older nest chamber (37 cm x 20 cm x 20 cm) was unearthed just behind and below the first one at a depth of 44 cm. The older nest was comprised of 22 hatched egg shells and 13 unhatched eggs. A colony of the non-native Solenopsis invicta Buren (Red Imported Fire Ant) was disturbed by excavation of the nest mound. There was no evidence that the ants’ presence had negatively impacted tegu nesting. Discussion There is growing evidence that the number of established non-native reptiles and amphibians, as well as their respective populations and ranges, are increasing rapidly in Florida (Krysko et al. 2011a, b; Meshaka 2011). Our data provide the first evidence confirming expansion of a reproducing population of Argentine Black and White Tegus into southeastern Florida. If this population is small and localized, there is potential for eradication if swift, decisive action is taken. As with Python molurus bivittatus Kuhl (Burmese Python) (Snow et al. 2007), radio telemetry proved to be an effective technique for documenting presence of Argentine Black and White Tegu nests. The clutch sizes found (21 this year and 35 from earlier) are within the range of 20 to 50 eggs reported for Argentine Tegus (Donadío and Gallardo 1984) in their native range. Pierre (pers. comm. in Enge 2007) predicted that tegu nests would be constructed at the base of a tree or under a log or other surface object as we found in southeastern Florida. In its native range, the Argentine Black and White Tegu occurs in forested, open, and disturbed habitats (Fitzgerald 1994). Tegus can be found in wet areas such as flooded savannas and streams (Norman 1987), and they also seem to prefer areas with opportunities for burrows (Balsai 1998). In west-central Florida, Argentine Black and White Tegus have been found in natural (scrub) habitats, especially in association with Gopher Tortoise, Gopherus polyphemus (Daudin) burrows (Enge 2007, Engeman et al. 2011). Our study area is comprised of disturbed habitat and is in close proximity to water with artificially elevated areas for nests and burrows. This habitat feature is commonly found along canals and ponds surrounding our study area and throughout southern Florida. From telemetry data, we have evidence of tegus dispersing from our study area along and across canals (unpubl. data). Without control, it is possible that this population will expand to other areas, especially along and across canals, levees, and roads. Tegus are known to be egg predators (Achaval 1977, Escalona and Fa 1998). In southeastern Florida, their presence could endanger nests of sea turtles, Alligator mississippiensis (Daudin) (American Alligator), and Crocodylus acutus (Cuvier) (American Crocodile). Nests of American Crocodiles at the Florida Power and Light Company’s Turkey Point Power Plant site are particularly at risk since they are within dispersal distance (10 km) of current locations of tegus. Although adverse impacts of the Argentine Black and White Tegu have yet to be detected, management action is warranted before individuals disperse farther in the region. Waiting to act would limit management options, decrease the probability that they will be successful, and ensure that they are more expensive 2012 T. Pernas, D.J. Giardina, A. McKinley, A. Parns, and F.J. Mazzotti 769 (Byers et al. 2002). Since we know that Argentine Tegus are established (reproducing) in Florida, the time for action is when individual tegus and nests are first discovered at new locations prior to detection of detrimental impacts. Acknowledgments This study was supported by the National Park Service and the Florida Fish and Wildlife Conservation Commission. Preparation of the manuscript was supported by the University of Florida. We thank Rebecca Harvey and Sara Williams for formatting and editing this manuscript. Walter Meshaka, Kenneth Krysko, Jennifer Eckles, and Scott Hardin provided valuable comments that greatly improved this manuscript. 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