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Pond Slider (Trachemys scripta*)

[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_single_image image=”2173″ img_size=”large” alignment=”center” style=”vc_box_rounded”][vc_column_text]Pond Slider, Pima County, AZ. Photo by Jim Rorabaugh[/vc_column_text][/vc_column][vc_column width=”1/2″][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”2204″ img_size=”medium” alignment=”center” onclick=”img_link_large”][vc_column_text]Pond Slider, Tucson, AZ. Photo by Jim Rorabaugh[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”2205″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Pond Sliders, Kingfisher Pond, Upper San Pedro River. Photo by Jim Rorabaugh[/vc_column_text][/vc_column_inner][/vc_row_inner][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”2203″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Pond Slider, Phoenix Zoo Ponds. Photo by Jim Rorabaugh[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”2206″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Pond Slider, Fort Lowell Park, Tucson © 2009 Susan Beebe / ASDM Sonoran Desert Digital Library[/vc_column_text][/vc_column_inner][/vc_row_inner][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”2207″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Pond Slider, Sweetwater Wetlands, Tucson © 2010 Pat Goltz / ASDM Sonoran Desert Digital Library[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column width=”1/6″][/vc_column][vc_column width=”2/3″][vc_column_text]

Description

The slider is a medium-sized (to 14.5 in [37 cm]) freshwater turtle.  Consisting of many subspecies (experts disagree on the exact number of distinct subspecies), Trachemys scripta occurs from New Mexico east to the Atlantic Coast and from southern Michigan south though Columbia and Venezuela.  As might be expected for a wide-ranging species, this turtle is a habitat and dietary generalist.  Sliders generally inhabit freshwater ponds or areas or those with slow moving water, but can also be found in brackish water and salt marshes.  Sliders eat just about any plant or animal food they can find, but as they age a higher proportion of plant matter makes up their diet.  In the United States the Red-eared Slider (Trachemys scripta elegans; the subspecies we are concerned about in this account) occurs naturally in the Mississippi Valley from Illinois to the Gulf of Mexico.

In the 1950’s through the 1970’s, millions of baby sliders per year were sold as pets both in the United States and abroad, a practice that continues to a lesser extent today despite federal legislation that was enacted in 1975 to restrict the sale of turtles under 4 in (10 cm). Health workers passed this legislation to limit children’s exposure to Salmonella.  Loopholes in the USDA law banning the sale of turtles less than 4 inches allow for the sale of hatchlings for “educational” purposes; thus, many pet stores have now taken on an altruistic role and offer very small turtles for sale as “educational aids.” Another loophole allows giving hatchlings away free provided the customer buys a turtle “starter kit” (aquarium, food, lighting, etc.), priced so that the cost of the hatchling turtle is combined into  the cost of the entire kit.  Lastly, many people, customers and sellers alike, remain unaware of this rather obscure law.  In the example illustrated (Fig. 1 – see the original article), three baby turtles were sold to passersby in approximately five minutes, and the author heard such dubious advice as “the females are the larger ones” (baby sliders cannot be sexed outwardly, and it is doubtful that chromosomal assays were conducted prior to sale), and “you don’t need to feed them.  They’ll live off the algae in your pond.”  That, of course, assumes one’s pond has algae.  Otherwise, the seller has just guaranteed the young turtle will meet a slow but sure demise.

One unfortunate result of this massive glut of impulse-bought turtles is that, of those turtles that do not die outright in captivity, many are released into the wild, contrary to Arizona Revised Statutes Title 17-306 which prohibits the release of such wildlife into the state. In many cases, released turtles simply die soon after release; in others, the turtles survive, grow large, and then die without finding mates and reproducing. Sometimes, however, released turtles find other also-released turtles, they mate, babies hatch, and an introduced population is established.  Red-eared Sliders may now be established in Belgium, the British Isles, Czechoslovakia, France, Germany, Italy, Spain, Sweden, Israel, Japan, South Korea, Taiwan, Saudi Arabia, Malaysia, Singapore, Sri Lanka, Thailand, South Africa, New Zealand, Bermuda, the West Indies, parts of South America, the Mariana Islands, Slovakia, and the western United States, including Hawaii and many parts of lower-elevation California.  Because of this world-wide success, the species is now recognized by IUCN as one of the world’s 100 worst invasive species.

Red-eared Sliders are, for better or worse, part of Arizona’s herpetofauna; hence this 100-mile circle species account.  However, the Red-eared Slider is not widespread here in large part due to its need for perennial water.  Sliders occur in Arizona in parts of the Colorado and Gila drainages and near the San Pedro River at Kingfisher Pond (Sierra Vista).  Nearer to Tucson, this animal can be observed at many golf-course ponds and regional parks, including Agua Caliente, Reid Park, the Sweetwater Ponds Sewage Plant, Fort Lowell, and on the University of Arizona campus.  In these situations, Red-eared Sliders may be part of a completely non-native urban herpetofauna.  Other introduced herps that may be observed alongside the slider vary, but may include softshell turtles (Apalone), Painted Turtles (Chrysemys picta), map turtles (Graptemys), Snapping Turtles (Chelydra serpentina), American Bullfrogs (Rana catesbeiana), and African Clawed Frogs (Xenopus laevis).  Obviously, urban ponds have become dumping grounds for unwanted aquatic herps.

Potential negative consequences of the wide-spread introduction of sliders are little studied, and in some cases may be benign, including in Arizona.  In completely urban settings, where wetlands have been created where once there were none, sliders may provide a glimpse of nature to people otherwise removed from wilderness.  There, they join park ducks, swans, and squirrels and provide enjoyment to a sedentary society that appreciates nature, any nature, regardless of origin. In these urban aquatic islands, perhaps Red-eared Sliders have their place, feeding on koi and grass carp, and being chased into the water by little kids and dogs. However, in natural settings, in places with connectivity to other waters and inhabited by native fauna, introduced turtles are a concern.  As you might imagine, the possible impacts of slider introductions on native turtles is context-specific.  For example, concerns are justified where this subspecies has been translocated into areas where endemic Trachemys scripta subspecies occur.  In those cases, swamping of local genetic diversity may occur to the detriment of the native taxon.  Genetic diversity and thus biodiversity may be lost, possibly handicapping the ability of future turtle generations to cope with landscape and climatic changes.  In other instances, this aggressive turtle may win competitive battles for limited resources such as basking sites.  Native turtles, relegated to sub-par basking sites, may not be allowed to thermoregulate appropriately, leading to slower growth rates and lower annual fecundity.  There is also the concern that released sliders might carry diseases from elsewhere into their newly established home and the turtles therein.  Clearly, other negative impacts can be imagined, not all of which might be to other turtle species.

It is one of the ironies of our time that among turtles, a group of organisms severely affected by human activities and facing certain anthropogenically-caused extinctions in the near future, the Red-eared Slider is so successful.  As the adage goes, a weed is just a flower out of place.  Thus it is for the Red-eared Slider; a successful and charismatic turtle in its natural range, but a weed and a pest when introduced around the world.

Thanks to Ed Moll for his helpful comments on this species account.

References

Arizona Game and Fish Department. 2005. Arizona Game and Fish Laws and Rules.

Ernst, C. H., J. E. Lovich, and R. W. Barbour.  1994. Turtles of the United States and Canada. Smithsonian Institution Press, Washington, D. C.

Lever, C.  2003.  Naturalized Reptiles and Amphibians of the World.  Oxford University Press, New York.

Moll, D. and E. O. Moll.  2004.  The Ecology, Exploitation, and Conservation of River Turtles. Oxford University Press, New York.

Stebbins, R. C.  2003.  Western  Reptiles and Amphibians.  Houghton-Mifflin Co., Boston – New York.

 

Author: Eric Stitt

Originally published in the Sonoran Herpetologist 2005 18(6):65-66

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