Argentine Black and White Tegu (Salvator merianae) can survive the winter under semi-natural conditions well beyond their current invasive range

Abstract

The Argentine Black and White Tegu (Salvator merianae, formerly Tupinambis merianae) is a large lizard from South America. Now established and invasive in southern Florida, and it poses threats to populations of many native species. Models suggest much of the southern United States may contain suitable temperature regimes for this species, yet there is considerable uncertainty regarding either the potential for range expansion northward out of tropical and subtropical zones or the potential for the species establishing elsewhere following additional independent introductions. We evaluated survival, body temperature, duration and timing of winter dormancy, and health of wild-caught tegus from southern Florida held in semi-natural enclosures for over a year in Auburn, Alabama (> 900 km northwest of capture location). Nine of twelve lizards emerged from winter dormancy and seven survived the greater-than-one-year duration of the study. Average length of dormancy (176 d) was greater than that reported in the native range or for invasive populations in southern Florida and females remained dormant longer than males. Tegus grew rapidly throughout the study and the presence of sperm in the testes of males and previtellogenic or early vitellogenic follicles in female ovaries at the end of our study suggest the animals would have been capable of reproduction the following spring. The survival and overall health of the majority of adult tegus in our study suggests weather and climate patterns are unlikely to prevent survival following introduction in many areas of the United States far from their current invasive range.

Thermal stability of an adaptable, invasive ectotherm: Argentine giant tegus in the Greater Everglades ecosystem, USA

“…Indeed, the active period for tegus in our population is somewhat extended compared with areas in their native range where they may hibernate for 6 months (Andrade et al 2004). In southern Florida, tegus have also demonstrated the ability to modulate both T b (max) and T b(min) , even during temperature extremes, and have now been shown to tolerate colder winters in Alabama (Goetz et al 2021; present study; Appendix S3: Figs. S1, S2).…”

Individual heterogeneity influences the effects of translocation on urban dispersal of an invasive reptile

“…When fit to tegu movement data, our model can be used to predict where and how quickly tegus are likely to spread from reported sighting locations. Our approach can account for seasonal variations in behavior that occur in temperate climates, such as tegu brumation [ 74 – 76 ], by specifying movement probability as a function of temperature. In both of these applications, managers can obtain more biologically informed estimates of the spatial extent of an invasion as well as an understanding of invasion speed, helping them decide when and where they should direct interdiction or rapid response efforts.…”

The Stages of Invasion: How does a nonnative species transition to an invader?

“…Subsequent introductions have also resulted in established populations in Georgia (Haro et al 2020). This species is projected to spread to other areas in the southeastern United States based on its ability to hibernate and tolerate cold temperatures (Jarnevich et al 2018;Goetz et al 2021).…”