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      Red-eared slider (Photo: Wayne Van Devender) - Click for full size   Trachemys scripta elegans (Photo: Riccardo Scalera) - Click for full size   Red-eared slider (Photo: Wayne Van Devender) - Click for full size   Red-eared slider (Photo: unknown) - Click for full size   Red-eared slider (Photo: unknown) - Click for full size
    Taxonomic name: Trachemys scripta elegans (Wied-Neuwied, 1839)
    Synonyms: Chrysemys scripta (Boulenger 1889), Chrysemys scripta var. elegans Boulenger 1889, Emys elegans Wied 1839, Emys holbrooki Gray 1844, Emys sanguinolenta Gray1855, Pseudemys scripta elegans Stebbins 1985, Pseudemys scripta (Jordan 1899), Testudo scripta Schoepff, 1792, Trachemys lineata Gray 1873
    Common names: Buchstaben-Schmuckschildkröte (German), Krasnoukhaya cherepakha (Russian), Nordamerikansk terrapin (Danish), punakorvakilpikonna (Finnish), punakõrv-ilukilpkonn (Estonian), raudonausis vežlys (Lithuanian), raudonskruostis vežlys (Lithuanian), red-eared slider (English), red-eared slider terrapin (Bahamas), rödörad vattensköldpadda (Swedish), rødøret terrapin (Danish), rødøreterrapin (Norwegian), Rotwangen-Schmuckschildkroete (German), Rotwangen-Schmuckschildkröte (German), sarkanausu brunurupucis (Latvian), slider (English), tortue à tempe rouge (French), tortue de Floride (French), zólw czerwonolicy (Polish), zólw czerwonouchy (Polish), zólw ozdobny (Polish)
    Organism type: reptile
    The red-eared slider (Trachemys scripta elegans) has been the most popular turtle in the pet trade with more than 52 million individuals exported from the United States to foreign markets between 1989 and 1997. Despite the vast worldwide occurrence of the sliders little is known of their impact on indigenous ecosystems, clearly research and education on the dangers of releasing pet turtles into the wild are needed. Their omnivorous diet and ability to adapt to various habitats, gives them great potential for impacting indigenous habitats.
    Description
    Adult: The red-eared slider is a medium (carapace length: 125 to 289 mm; Somma & Fuller 2009; 150 - 350 mm; Obst 1983) freshwater turtle characterised by prominent yellow to red patches on each side of the head, typically red on T. scripta elegans (Scalera 2006). Carapace and skin are olive to brown with yellow stripes or spots; males are usually smaller than females and have a long, thick tail (Scalera 2006).
    Eggs: The eggs are ovoid in shape, 31 to 43 millimeters long, 19 to 26 millimeters wide and weigh 6.1 to 15.4 grams (Bringsøe 2006).
    Occurs in:
    lakes, riparian zones, water courses, wetlands
    Habitat description
    Within its natural range Trachemys scripta lives in a wide variety of freshwater habitats including rivers, ditches, swamps, lakes and ponds (Bringsøe 2006). T. scripta prefers large quiet water bodies with soft bottoms, an abundance of aquatic plants and suitable basking sites (Carr 1952, Ernst et al. 1994, Bringsøe 2001b, in Bringsøe 2006). Although they prefer quiet waters, red-eared sliders are highly adaptable and can tolerate anything from brackish waters, to manmade canals, and city park ponds (Ernst et al. 1994, Cox et al. 1998, Salzberg 2000, in Somma & Fuller 2009). Small turtles usually limit their activity to areas of heavy floating vegetation. It is thought that the terrapins do not feed or grow beyond temperature range of 10°C to 37°C (Ramsay et al. 2007).

    In Europe, T. scripta elegans are generally released in freshwater areas which are frequented by humans such as public ponds which are considered of low biological value (e.g. Kordges 1990, Thiesmeier & Kordges 1990 1991, in Bringsøe 2006). Natural habitats close to urban areas are also used for releases (Bringsøe 2006). Natural reproduction of the red-eared slider in Europe under Mediterranean climate conditions has been reported (Luiselli et al. 1997, Martinez-Silvestre et al. 1997, Cadi et al. 2003, in Cadi & Joly 2003). The occurrence of the red-eared slider in a tropical urban polluted river in Brazil supports evidence of its capacity to use anthropogenic environments. Polluted rivers can offer a high amount of organic residues and food items, which can represent an advantage for such a generalist freshwater turtle species (Moll 1980, Lindeman 1996, Souza & Abe 2000, in Ferronato et al. 2009).

    General impacts
    For a detailed account of the environmental impacts of T. scripta elegans please read: Trachemys scripta elegans (red-eared slider) Impacts Information. The information in this document is summarised below. Trachemys scripta elegans has been the most popular turtle in the pet trade with more than 52 million individuals exported from the United States between 1989 and 1997 (Telecky 2001, in Bunnell 2005). Slider turtles became very popular because of their small size, their simple husbandry requirements and their reasonably low price (Teillac-Deschamps et al. 2008). Unsuspecting turtle owners were rarely prepared to maintain large adults (up to 30 cm carapace length) for a significant length of time (up to 50 years) in captivity (Teillac-Deschamps et al. 2008). Larger adult turtles were released by their owners to ponds in many places and because of this, red-eared sliders now occur in freshwater ecosystems in many developed countries with high densities in urban wetlands (de Roa & Roig 1997, Luiselli et al. 1997, Arvy & Servan 1998, Chen & Lue 1998, Lever 2003, Martinez-Silvestre et al. 2003, in Teillac-Deschamps et al. 2008).

    Competition: The competitive advantages of the slider may include lower age at maturity, higher fecundity, and larger adult body size (Arvy & Servan 1998, in Cadi & Joly 2003). Turtles may compete for food, egg-laying sites, or basking places (Bury & Wolfheim 1973, Bury et al. 1979, Rovero et al. 1999, Lindeman 1999, in Cadi & Joly 2003). In a study by Cadi and Joly (2003), Emys were shown to shift their basking activity toward places considered to be of lower quality, while the dominant Trachemys occupied the better basking sites. Other studies have also shown red-eared sliders to compete with indigenous species for food and basking sites (Frank & McCoy 1995, Williams 1999, Salzberg 2000, in Somma & Fuller 2009). The red-eared slider has also been considered occasionally aggressive towards other individuals (Cadi & Joly 2003).

    Threat to Endangered Species: Competitive interactions between T. scripta elegans and the European pond turtle (Emys orbicularis) are of particular interest, as the latter is registered as an endangered species (Appendix II of the Bern Convention, Corbett 1989, Luiselli et al. 1997, Martinez-Silvestre et al. 1997, in Cadi & Joly 2003, see Competition).

    In Washington (USA) they are a potential threat to the Pacific pond turtle (Clemmys marmorata) a declining species endemic to the Pacific states (Brown et al. 1995, Williams 1999, in Somma & Fuller 2009).

    Disease Transmission: Continuous releasing of exotic pet turtles in natural ecosystems increases the risk of parasite transmission to native species, and highlights the impending need for regulation of pet turtle trade in Europe (Hidalgo-Vila et al. 2008); the red-eared slider is known to carry nematodes (Hidalgo-Vila et al. 2008).

    Predation: Turtles introduced near Paris were revealed to have consumed aquatic plants and animals (mostly arthropods and molluscs, Prévot-Julliard et al. 2007, in Teillac-Deschamps et al. 2008).

    Human Health: Reptiles, including turtles, are well-recognised reservoirs for Salmonella, and are a source of human salmonellosis (Nagano et al. 2006).

    Ecosystem Change: The impacts of T. scripta on natural habitats and ecosystems are unknown; should the red-eared slider be released in natural habitats with high ecological value, it would be relevant to monitor any consequences on native fauna and flora, typically invertebrates, amphibians, native turtles and nesting birds (Bringsøe 2006).

    Notes
    Previously the red-eared slider was considered a widely distributed New World species consisting of 13 to 19 subspecies, however, today the Latin American taxa are included in other species and T. scripta only consists of the three North American subspecies, i.e. T. s. scripta, T. s. elegans and T. s. troostii (Bringsøe 2001a, Seidel 2002, in Bringsøe 2006).

    Besides its distinctive red flashes the red-eared slider (like all turtles exotic to Australia) can also be identified by the way it retracts its head straight back into the shell; in comparison, all native Australian turtles wrap their heads around to the side of their shell (NRM&W).

    Geographical range
    Native Range: Trachemys scripta is present in eastern USA and adjacent areas of Mexico. It ranges from Virginia southwestward through to Florida, Alabama, Mississippi, Louisiana and Texas to Mexico. To the north, the distribution of T. scripta reaches through Kentucky and Tennessee to Ohio, Indiana, Illinois and Iowa, and west to Kansas, Oklahoma and New Mexico. T. scripta scripta has an eastern range and occurs from southeastern Virginia to northern Florida. T. scripta elegans dominates within this species and has a western and central range. It is occupies the Mississippi Valley from Illinois via parts of eastern New Mexico in the west to the Gulf of Mexico. Towards southeast it overlaps with T. s. scripta in Alabama (and adjacent areas) and forms a zone of intergradation. T. scripta troostii has a small distribution and is found in the upper portions of the Cumberland and Tennessee rivers, from southeastern Kentucky and southwestern Virginia through Tennessee to northeastern Alabama. (Native range description taken from Bringsøe 2006).
    Known Introduced Range: The release of turtles has occurred in Europe (Warwick 1991, in Cadi et al. 2004), Africa (Newberry 1984, in Cadi et al. 2004), South America (Girondot Pers. Obs., in Cadi et al. 2004) and Asia (Warwick 1991, Moll 1995, Chen and Lue 1998, in Cadi et al. 2004). Trachemys scripta generally has a scattered distribution in the North European and Baltic region, with occurrences in or near urban areas (Bringsøe 2006).
    Introduction pathways to new locations
    Pet/aquarium trade: Since the 1970s, massive numbers of young slider turtles have been generated on turtle farms in the USA for the pet trade. The most commonly exported species is the red-eared slider T. scripta elegans, with more than 52 million individuals being produced for foreign markets between 1989 and 1997 (Telecky 2001, in Cadi et al. 2004). As slider turtles are often sold as small hatchlings (three to four centimeters carapace length), unsuspecting owners are rarely prepared to continue maintaining them in captivity when the turtles reach adulthood (up to 30 centimeters carapace length) (Cadi et al. 2004). Often, larger turtles are released by their owners, which has led to the introduction of many slider turtles into natural ecosystems (Cadi et al. 2004). This interest in pet turtles may have reached a peak during the Teenage Mutant Ninja Turtle television cartoon craze of the late 1980s and early 1990s (Somma & Fuller 2009).


    Local dispersal methods
    Intentional release: As red-eared sliders reach adulthood, many are released by their owners into natural ecosystems (Cadi et al. 2004).
    Natural dispersal (local): Red-eared sliders may disperse up to 2 km to lay eggs (Gibbons et al. 1983, in O'Keeffe 2009).
    Management information
    For a detailed account of the environmental impacts of the red-eared slider please read: Trachemys scripta elegans (red-eared slider) Management Information. The information in this document is summarised below.

    Preventative measures: With effect from 22 December 1997 the EU banned the import of the subspecies T. scripta elegans via the Protection of Species of Wild Fauna and Flora by Regulating Trade (Bringsøe 1998, 2001b, Bringsøe 2006). While it is no longer allowed to import the red-eared slider within the EU it is still legal to keep and distribute them within many EU countries.

    After this legislation was passed the red-eared slider was semi-replaced in the market by other North American turtles which fetch higher prices and are imported in lower quantities (Adrados et al. 2002, in Bringsøe 2006). This may change if American turtle farmers manage to improve breeding success of these species in turtle farms. Unfortunately some of the species replacing the red-eared slider in the market are substantially better adapted to cold climates (such as Nova Scotia and Siberia, respectively) and probably represent a higher ecological risk; they are cryptic species and are significantly more carnivorous than the red-eared slider (P.P. van Dijk Pers. Comm. 2006).

    Risk Assessment models for assessing the risk that exotic vertebrates could establish in Australia have been further explored by the Western Australia Department of Agriculture & Food (DAFWA) to confirm that they reasonably predict public safety, establishment and pest risks across a full range of exotic species and risk levels.
    The Risk assessment for the Pond Slider (Trachemys scripta), has been assigned a VPC Threat Category of EXTREME.
    Mammals and birds were assessed for the pest risk they pose if introduced to Australia, by calculating Vertebrate Pests Committee (VPC) Threat Categories. These categories incorporate risk of establishing populations in the wild, risk of causing public harm, and risk of becoming a pest (eg causing agricultural damage, competing with native fauna, etc). The 7-factor Australian Bird and Mammal Model was used for these assessments.

    Physical: Sliders can be captured by hand or through various trapping devices. Please visit Fyke Net for Turtles for information about turtle nets. Floating boards used by sliders as basking sites seem very effective when equipped with baited cages on top (Scalera 2006). Sniffer dogs can be used to detect and remove both turtles and their eggs; eggs can also be found and removed by following females at nesting areas (Scalera 2006).

    In parts of Asia animals are released into the wild as a part of traditional Buddhist mercy ceremony to increase good karma, honour Buddha and repent for ones sins. The Ministry of the Environment (Republic of Korea ) advised that people should consider taking care of injured birds and animals and then set them free for a more environmentally-friendly symbolic act.

    Knowledge and Research: The ecological effects of introductions of T. scripta elegans have been poorly documented (Platt & Fontenot 1992, in Ramsay et al. 2007). Competition of T. scripta elegans with the 'Lower Risk/Near Threatened (NT)' indigenous European pond turtle (see Emys orbicularis in the IUCN Red List of Threatened Species) has been studied in France (see Cadi & Joly 2003). A French management project for the red-eared slider was initiated by the laboratory “Ecologie, Systématique and Evolution” (CNRS-University Paris-Sud) (Cadi et al. 2008).

    Nutrition
    The red-eared slider is an opportunistic omnivore subsisting on a wide variety of plants and animals (Ernst et al. 1994, in Bringsøe 2006) including filamentous algae, macrophites, snails, Diptera (larvae and pupae), terrestrial insects, crustaceans and small vertebrates (Chen & Lue 1998, Prévot-Julliard et al. 2007, in Ferronato et al. 2009). Juveniles are mainly carnivorous and as they grow older they become more herbivorous (Bringsøe 2006). Prévot-Julliard et al. (2007) found a decrease of invertebrate consumption with age of the turtle. Carr (2008) observed specimens of red-eared slider consuming grass blades (southern watergrass and teal lovegrass). Adult turtles will still opportunistically eat aquatic invertebrates (especially insects and molluscs), fish, frog eggs, tadpoles and aquatic snakes (Ernst et al. 1994, Brown et al. 1995, in Somma & Fuller 2009). T. scripta elegans in seminatural basins in Milan (northern Italy) selected insects (40%) over most other food items (Agosta & Parolini 1999).

    In northern Taiwan all feral T. scripta elegans sampled were found to have ingested animal materials (mostly snails, fish, adult and larval flies and unidentifiable terrestrial insects) and 76.5% were found to have ingested plant materials (Chen & Lue 1998, in Outerbridge 2008). Conversely Outerbridge (2008) found that only 77.8% of feral red-eared sliders examined in Bermuda had ingested animal materials whereas 86.1% had ingested plant materials. Most of the vegetative matter consisted of leaves, stalks, roots, seeds and flowers; however, filamentous and blue-green algae were also occasionally ingested. Nearly half of the animal material ingested comprised aquatic and terrestrial insects. Small fish, freshwater snails and bird remains occurred less frequently in the samples (Outerbridge 2008).

    Prévot-Julliard et al. (2007) found fish remains in the stomachs of turtles. The size of fish scales found, some up to 12 mm in diameter, would have belonged to 20 cm fish (J.Y. Sire, Pers. Comm., in Prévot-Julliard et al. 2007). As it is unlikely that a slider turtle would be rapid enough to catch a 20 cm fish, perhaps the turtle acted as a necrophagous species, as other species of freshwater turtles do (Spencer et al. 1998, in Prévot-Julliard et al. 2007).

    Prévot-Julliard et al. (2007) found four individuals which had ingested terrestrial ants, and one stomach was full of them. Although terrestrial activity is known for this species (Bennett et al. 1970, Gibbons 1970, in Prévot-Julliard et al. 2007), only few report are available for terrestrial foraging (Cagle 1944, Chen & Lue 1998, in Prévot-Julliard et al. 2007). The terrestrial activity of slider turtles is a key component for the colonisation of new habitat (Parker 1990, in Prévot-Julliard et al. 2007) making further investigation into this aspect of the turtle’s behavior warrented.

    Reproduction
    Sexual maturity is reached in the third to fourth year (Obst 1983, Pupins Unpub. Data, in Pupins 2007). T. scripta exhibits complex courtship behaviour in the water. The female usually excavates a nest on the shore of a freshwater body or on beaches in places such as Costa Rica (Bringsøe 2006; Scalera 2006). Females may move as far as 1.6 kilometers to find a suitable nest site; the jug-shaped nest is generally up to 12 centimeters deep (Bringsøe 2006). Depending on body size and other factors up to six clutches a year containing up to 30 eggs may be laid; mean values of natural populations is around 6 to 11 eggs per clutch (Bringsøe 2006; Scalera 2006). Mean annual fecundity for T s. elegans in Illinois and Louisiana is close to the 30 eggs per year (estimated by Cagle 1950 and Thomhill 1982, in Tucker 2001). Mean annual fecundity estimates for the T. scripta scripta from South Carolina seem exceedingly low in comparison (Tucker 2001). Incubation takes 59 to 112 days (Scalera 2006). Hatching times are weather dependent: temperatures between 22°C to 30°C for 55 to 80 days are preferred (Pendlebury 2006, in Pupins 2007). Hatching of eggs requires 50 to 60 days at 26 °C. Longevity is approximately 20 years in the wild and 40 years in captivity.

    In its introduced range in Europe egg deposition has been observed in Spain (de Roa and Roig, 1997; Martinez-Silvestre, 1997; Bertolero and Canicio, 2000; Capalleras and Carretero, 2000, in Cadi et al. 2004), and near Paris, France (Moran Pers. Comm., in Cadi et al. 2004). However, sex determination of the Trachemys embryos is temperature-dependent, with cooler incubation temperatures producing only males, and warmer incubation temperatures only females (Ewert et al. 199, in Cadi et al. 2004). Therefore, incubation temperature could be a limiting factor for the invasion of this species in parts of Europe, if hatchlings of only one sex are produced in the wild (Cadi et al. 2004). A strong bias towards female red-eared sliders has been detected in capture sampling in France. This may reflect a potential strong female bias of imported juveniles; the incubation at high temperature leads to rapid hatching, but produces females in this species with temperature dependent sex determination (Godfrey et al. 2003, in Prévot-Julliard et al. 2007).

    Lifecycle stages
    Red-eared sliders can live for about 40 years (Scalera 2006). Therefore even if reproduction does not occur, they can survive in the wild for many years.
    This species has been nominated as among 100 of the "World's Worst" invaders
    Reviewed by: Paul Pendelbury, REPTRANS UK
    Compiled by: IUCN SSC Invasive Species Specialist Group
    Updates with support from the Overseas Territories Environmental Programme (OTEP) project XOT603, a joint project with the Cayman Islands Government - Department of Environment
    Last Modified: Wednesday, 26 May 2010


ISSG Landcare Research NBII IUCN University of Auckland