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Dietary Notes on the Red-eared Slider (Trachemys scripta) and River Cooter (Pseudemys concinna) from Southern Illinois
Abstract
The primary focus of this study was to ascertain the presence of sexual, seasonal, or ontogenetic differences in the diets of Trachemys scripta and Pseudemys concinna cap-tured at Round Pond, Gallatin County, Illinois, between 17 May 1994 and 30 August 1995. I collected feces from T. scripta and P. concinna and separated the contents into eleven dietary categories for T. scripta and two for P. concinna. I quantified fecal vol-ume by water cc displacement, then described each dietary category by frequency of occurrence, percent volume, and relative percent volume. Juvenile T. scripta fecal con-tents comprised >70% plant matter, while adult males and females had equal proportions of plant and animal matter in their feces. Percent volume and relative percent volume for T. scripta fecal samples did not differ between males and females, or between females and juveniles; however, I detected significant differences between males and juveniles and early (May-June) and late (July-August) samples. Overall the diversity of food items in the diet of T. scripta was large (Shannon index = 2.50) and the diversity of items expanded from early (Shannon index = 1.19) to late season (Shannon index = 2.72). Females consumed more mollusks than males, and males and females consumed more bryozoans than juveniles. I found Mollusks and bryozoans only in late season samples. Pseudemys concinna was herbivorous, specializing on epiphytic filamentous algae of the genera Cladophora and Oedogonium, with no differences in the frequencies of occur-rence between males, females, and juveniles.
... At the Black River, the 2 species showed differing d 13 C signatures, suggesting utilization of different basal dietary sources. At Berrendo Creek, T. s. elegans had an enriched d 15 N signature, suggesting a more carnivorous diet relative to P. gorzugiunsurprising given the larger amounts of animal matter typically found in stomach and fecal contents of T. scripta (Parmenter 1980;Dreslik 1999;Lindeman 2000;Bassett and Forstner 2021). ...
... Additionally, many of the food items identified in the feces of P. gorzugi from San Felipe Creek have also been reported in the diet of P. texana including filamentous algae, C. caroliniana, C. demersum, Myriophyllum, and crayfish (Lindeman 2001;Fields et al. 2003;Ernst and Lovich 2009). Prior studies have likewise described P. concinna as primarily algivorous or herbivorous (Lagueux et al. 1995;Dreslik 1999;Lindeman 2000). For example, Lindeman (2000) found that algae accounted for . ...
... 99% of the ash-free dry mass of P. concinna fecal samples. Many of the food items identified in the feces of P. gorzugi from San Felipe Creek have also been reported in the diet of P. concinna including filamentous algae, crayfish, gastropods, hymenopterans, grasses, and C. demersum (Cahn 1937;Parker 1939;Buhlmann and Vaughan 1991;Lagueux et al. 1995;Dreslik 1999;Lindeman 2000). Our results therefore serve as additional evidence indicating that members of the genus Pseudemys primarily rely on algae and vegetation to fulfill bioenergetic demands. ...
The Rio Grande cooter (Pseudemys gorzugi) is an imperiled freshwater turtle native to the southwestern United States and northeastern Mexico. Previous studies investigating P. gorzugi diet have focused on the population occupying the Black River drainage in southeastern New Mexico, while Texas populations have remained unexamined. During the summer and fall of 2020, we studied the dietary habits of P. gorzugi and the syntopic red-eared slider (Trachemys scripta elegans) at San Felipe Creek, Texas, USA using fecal content and stable isotope analyses. We also compared the isotopic niches of these 2 co-occurring turtle species. Filamentous algae were, volumetrically, the most important food item for male, female, and juvenile P. gorzugi. Stable isotope mixing models indicated that lotic and lentic filamentous algae had the greatest proportional contribution to P. gorzugi and T. s. elegans diets, respectively. Stable isotope dietary mixing models also indicate T. s. elegans had a more carnivorous diet, composed mostly of red-rimmed melania (Melanoides tuberculata) and red swamp crayfish (Procambarus clarkii). Carnivory in this species was further supported by enriched δ15N values and higher trophic position estimates. Pseudemys gorzugi and T. s. elegans had δ13C and δ15N signatures that significantly differed, and the 2 species showed little overlap in isotopic niche space, suggesting a low likelihood of intense resource competition. Our results demonstrate that the diet of P. gorzugi, and the isotopic niche overlap between P. gorzugi and T. s. elegans at San Felipe Creek differ from that in the Black River drainage of New Mexico. The information provided here contributes toward a more complete understanding of P. gorzugi ecology, is useful for identifying suitable habitat worthy of conservation, and can help guide the development of feeding regimes for captive assurance colonies.
... The diet of Pond Sliders has been investigated both in their native (e.g., Cagle 1950, Dreslik 1999, Hart 1983, Stephens and Ryan 2019 and introduced (e.g., Chen and Lue 1998, Lee and Park 2010, Outerbridge 2008, Works and Olson 2018, Zhang et al. 2020 ranges. They are typically referred to as opportunistic omnivores (Ernst et al. 1994, Parmenter andAvery 1990). ...
... Juveniles have higher metabolic needs, are better active predators, and need the calcium-rich animal foods they prey upon for rapid growth and maturation (Bouchard andBjorndal 2006, Hart 1983). However, variation from this ontogenetic dietary shift, with adults consuming more animal matter, does exist in some populations both in their native (Dreslik 1999) and introduced (Chen and Lue 1998, Pérez-Santigosa et al. 2011, Zhang et al. 2020 ranges. This dietary plasticity is among the reasons why this highly adaptable and ecologically tolerant species can thrive all over the world outside of its native range. ...
Most animal matter in the diet of the omnivorous Trachemys scripta (Pond Slider) consists of invertebrate prey items such as insects, crustaceans, and mollusks, but often also includes fish and amphibians. Reptiles, birds, and mammals are less commonly reported, and even when found, it is usually unknown if they were captured alive, as Pond Sliders will certainly scavenge dead animals. Though it is well known that Chelydra serpentina (Snapping Turtle) will prey upon waterfowl from the water surface, reports of such encounters are seemingly rare in Pond Sliders. Here, we document with video evidence an adult female T. s. elegans (Red-eared Slider) emerging from the water to successfully take and drown an Anas platyrhynchos (Mallard) duckling.
... Overweight, accelerated growth rate and metabolic bone disease of nutritional origin are common as a result of inadequate nutrition and housing (1,2,3,4,5). The natural diet of aquatic chelonians consists of several animal species, and seasonality is strong in the case of tortoises (6,7,8,9,10,11,12,13). Captive chelonians should be fed a natural diet to achieve a growth rate similar to that of free-ranging animals (2,3,7,15). ...
... Carbohydrates have the lowest importance with less than 10% DM (12). Many of the freshwater turtles are opportunistic carnivores or omnivores, as they undergo an ontogenetic shift in their diet as they mature (6,11,14,51,52,53,54,55,56,57,58). This dietary shift can be explained by the hypothesis that larger turtle species are less able to meet their metabolic requirements on a carnivore diet, have greater capacity to store fats and can cover their energy requirements on a plant diet as well. ...
Captive chelonians should be fed a natural diet to achieve a growth rate similar to that of free-ranging animals. A wide range of commercially formulated foods dedicated to chelonians is available. Feeding commercial foods has the advantage of convenience. On the other hand, species-specific information on the nutritional requirements of chelonians is not available yet. The aim of this study was to analyse and evaluate commercial pellets and feeds for chelonians. Commercial pellets (ntortoise = 7, nturtle = 7, from 6 companies) dedicated to carnivorous aquatic turtles and herbivorous terrestrial tortoises, and other aquatic turtle feeds (lyophilised beef heart, dried aquatic invertebrates, and whole frozen fish) were bought in pet shops. Whole frozen fish served as a reference feed for carnivorous aquatic turtles. The chemical composition as well as calcium (Ca) and phosphorus (P) contents were determined. Single-sample t-test was used with the label information as null hypothesis and the results of own parallel analyses for crude protein (CP), ether extract (EE), crude fibre (CF), Ca and P. The labelling of some of the pellets was deficient as nutritive values, Ca or P data were missing (tortoise pellets: 4 out of 7; turtle pellets: 5 out of 7). The label data differed significantly (p<0.05) from the results of our own analysis for 13 out of the 14 pellets. None of the tortoise pellets met the requirements of the animals completely. Because of the inadequate Ca:P ratio only one turtle pellet could be accepted. Accordingly, none of the commercial pellets can be recommended as main or only feed. Key words: nutrition; pellet; metabolic bone disease; chelonian VREDNOTENJE KOMERCIALNIH ŽELV IN KRME ZA ŽELVE Izvleček: Želve v ujetništvu je potrebno hraniti z naravno krmo, da dosežejo podobno stopnjo rasti kot živali v prosti reji. Na voljo je širok izbor komercialno pripravljene hrane za želve. Prednost hranjenja želv s komercialno hrano je priročnost, vendar podatki o prehranskih potrebah za posamezne vrste želv še niso na voljo. Namen te raziskave je bil analizirati in ovrednotiti komercialne pelete in krmo za želve. V trgovinah za živali smo od 6 podjetij kupili komercialne pelete (npeleti za vodne želve = 7, npeleti za kopenkse želve = 7) za mesojede vodne in rastlinojede kopenske želve ter drugo krmo za vodne želve (liofilizirano goveje srce, posušene vodne nevretenčarje in zamrznjene cele ribe). Zamrznjene cele ribe smo uporabili kot referenčno krmo za mesojede vodne želve. Določili smo kemično sestavo in vsebnost kalcija (Ca) ter fosforja (P). Za ničelno hipotezo smo uporabili T-test enega vzorca s podatki na etiketi in rezultate lastne paralelne analize za surove beljakovine (an gl. crude proteins, CP), ekstrakt etra (angl. ether extract, EE), surovo vlaknino (angl. crude fibre, CF), Ca in P. Oznake nekaterih peletov so bile pomanjkljive, saj so manjkali podatki o hranilnih vrednostih, Ca in P (npeleti za kopenske želve = 4 od 7, npeleti za vodne želve = 5 od 7). Podatki na etiketi so se bistveno razlikovali (p < 0,05) od rezultatov naše analize pri 13 od 14 vrst peletov. Nobeni peleti za kopenske želve niso v celoti izpolnjevali potreb živali. Zaradi neustreznega razmerja Ca : P smo kot ustrezno določili le eno izmed 7 vrst peletov za vodne želve, zaradi česar nobenih od komercialnih peletov nismo določili kot priporočljivih za glavno ali edino krmo za želve. Ključne besede: prehrana; peleti; presnovna bolezen kosti; želve
... In 2015, the EU regulation (1143/2014) on invasive alien (non-native) species came into force prohibiting Trachemys spp. from being rehomed, exchanged, sold, or bred (3). Evidence shows that they are highly invasive, yet there is little evidence on their impact or ability to thrive in the UK. ...
... Most records reported single individuals and it is surmised that they have less impact as opposed to larger groupings. Slider terrapins are noted as primarily herbivorous in their adult life stage (3). It is suspected that their impact on species such as ducks and fish as food items are minimal. ...
The Turtle Tally Citizen Science Project is raising awareness on the topic of released pet terrapins and gathering data on their distribution in UK waterbodies.
... This is because freshwater ecosystems have more negative δ 13 C values and more trophic levels than terrestrial ecosystems, which lead to elevated δ 15 N values in higher-order animals (Guiry 2019;Winemiller et al. 2011). This genus is, however, an opportunistic feeder, omnivorous on both land and water, and its diet may vary by age and sex (Bouchard and Bjorndal 2005;Dreslik 1999). Therefore, the elevated δ 13 C value of this individual may instead reflect a diet based on terrestrial C3 plants influenced by the "canopy effect", wherein recycled CO2 causes more negative δ 13 C values (van der Merwe and Medina 1991). ...
The Maya who inhabited southeastern Mesoamerica from the Preclassic to Colonial periods (1000 BCE to 1821 CE) have been the focus of intensive archaeological study for
over a century. Recent theoretical and methodological developments have contributed to
nuanced understandings of Maya migration and subsistence practices. Stable sulfur isotope (δ34S) analysis of bone collagen is a novel technique that has been applied to Maya skeletal collections, although the variation in environmental δ34S values throughout the Maya region has yet to be systematically characterized. This research presents the first Maya faunal sulfur isotope baseline based on the δ34S values of 148 archaeological faunal remains from 13 sites in the Northern and Southern Lowlands. As expected, terrestrial animals in coastal areas had elevated δ34S due to sea spray. However, those from inland sites had unexpectedly high δ34S values that varied depending on the age of the underlying limestone. Although the δ34S values of marine animals were lower than expected, similarly low values in freshwater animals permits the differentiation of freshwater and terrestrial animals at inland sites. These data demonstrate that sufficient variation in δ34S values exists in the Maya region to identify sources of protein and nonlocal animals, which speaks to prehispanic Maya animal exchange and interregional interaction. The δ34S values of 49 humans from seven Maya sites ranging from the Preclassic to Colonial periods were also interpreted using the faunal baseline. The spatial distribution of human δ34S values differed from that of the terrestrial fauna, demonstrating sociocultural variation in Maya resource procurement in addition to underlying environmental influences. A comparison of carbon and nitrogen data from the same individuals also revealed the consumption of protein from different catchments. Nonlocal δ34S values show three individuals migrated near the end of their lives, and when integrated with childhood strontium and oxygen isotope data from
tooth enamel, demonstrate a more robust means of investigating the length of residence and potentially the extent of integration into the receiving community. Finally, a case study of the prehispanic Maya from Nakum, Guatemala, demonstrates the contributions of stable sulfur isotope analysis to the interpretation of Maya subsistence strategies and migration when integrated into a multi-isotopic approach.
... Several dietary studies assessed the stomach and/or intestine content of Slider populations, both from the native range (Pierce, 1992;Dreslik, 1999;Stephens and Ryan, 2019) and from the non-native range (Prevot-Julliard et al., 2007;Outerbridge, 2008;Lee and Park, 2010;Pérez-Santigosa et al., 2011;Wang et al., 2013;Works and Olson, 2018). These identify both native and non-native populations as omnivorous, with different life stages having different diets; for example, smaller Sliders are more carnivorous, whereas adults are more herbivorous. ...
Pond Sliders, Trachemys scripta, are among the widest-spread animal species outside their native range, and habitat suitability modelling has demonstrated that the current range of this species can expand even further. This species is also widely reported in Europe with successful reproduction being reported mainly from southern locations, though increasingly from more northern populations, e.g., Germany. Nonnative Trachemys scripta impact native species and ecosystems, e.g., they can displace native turtle species and are known to harbour pathogens and parasites. Surprisingly little attention has been given to their impact on freshwater ecosystems, and additionally, dietary studies are few in number and do not implement a methodology that allows identification of all prey taxa. Here, we report how a live duckling (Anas platyrhynchos) was predated on by a large adult Trachemys scripta. The event, where the turtle grabbed the duckling from the water surface and submerged underwater, only took several seconds. Although vertebrate prey has been identified in stomach/intestine samples of Trachemys scripta, the general explanation has been this species’ scavenging behaviour. Our report provides an alternative explanation, namely predation of live prey that has not been frequently observed due to the speed of such events. Therefore, from a biological invasion perspective, the effect of non-native Trachemys scripta populations on native vertebrate fauna may be underestimated. We argue that to better understand the occurrence, frequency and diversity of prey in future dietary studies of Trachemys scripta (and other taxa), genetic techniques should be applied.
... Most turtle species are generalized omnivores (Lagler 1943;Vogt and Villarreal-Benitez 1997;Legler and Vogt 2013) and utilize the most abundant, easily obtained food in their habitats. Seasonality of available food resources forces turtles to change their preferences both quantitatively and qualitatively throughout the year (Mahmoud 1968;Dreslik 1999;Alcalde et al. 2010). Welsh et al. (2017) completed an elegant study in the tropical Daly River in the Northern Territory, Australia. ...
... This is because freshwater ecosystems have more negative δ 13 C values and more trophic levels than terrestrial ecosystems, which lead to elevated δ 15 N values in higher-order animals (Guiry, 2019;Winemiller et al., 2011). This genus is, however, an opportunistic feeder, omnivorous on both land and water, and its diet may vary by age and sex (Bouchard and Bjorndal, 2005;Dreslik, 1999). Therefore, the elevated δ 13 C value of this individual may instead reflect a diet based on terrestrial C 3 plants influenced by the "canopy effect", wherein recycled CO 2 causes more negative δ 13 C values (van der Merwe and Mediina, 1991). ...
The site of Nakum has been the subject of extensive archaeological investigation, but little is known of the subsistence practices or mobility of the Prehispanic Maya who lived there. This study employed a multi-isotopic approach to investigate the diet and mobility of the Nakum Maya. Despite the poor preservation typical of tropical environments, the isotopic compositions of five human bone samples were compared to carbon, nitrogen , and sulphur isotope baselines developed from 16 archaeological faunal specimens from Nakum. The bone collagen carbon and nitrogen results indicate that the Nakum Maya consumed a maize-based diet supplemented with other cultigens and animal protein. Stable carbon isotope values from the bioapatite of five human bone and seven human tooth samples show that maize was an important dietary component throughout life, although two individuals consumed less maize during childhood. The bone collagen sulphur data and strontium isotope results from three teeth indicate that the Nakum individuals consumed local foods. However, two human oxygen isotope values were lower than the local range developed from human bone and tooth enamel samples, indicating these individuals moved to the site from outside the Maya region. Although the faunal sulphur values were much higher than expected at an inland site due to the underlying marine carbonate limestone geology, one faunal sample exhibited a very low value, suggesting that it was imported to the site over a considerable distance. Finally, this is the first study to publish baseline sulphur isotope values derived from Maya faunal remains and contributes to a better understanding of this isotope system in the Maya region.
The epiphytic algae were studied on three aquatic plants (Ceratophyllum demersum, Myriophyllum verticillatum and Potamogeton pectinatus) from seven stations in Euphrates River between Hindia barrage and Al-Kufa city-Iraq, during summer 2004 and spring 2005. A total of (97) species were identified, diatoms were dominant in their species number (73% from the total number), followed by chlorophyta, then cyanophyta and Euglenophyta. Variations were recorded in the species number among the host macrophyte, as well as, among different seasons for each plant. The biomass of epiphytic algae varied among the plant host, diatoms species were dominated and several genera have large number of species as Cymbella, Gomphonema, Nitzschia and Synedra. Most studied stations showed high population density.
Although anticoagulant rodenticides (ARs) are effectively used for the control of invasive rodents, nontarget species are also frequently exposed to ARs and secondary poisonings occur widely. However, little data is available on the effects of ARs, especially on marine organisms. To evaluate the effects of ARs on marine wildlife, we chose green sea turtles (Chelonia mydas), which are one of the most common marine organisms around the Ogasawara islands, as our primary study species. The sensitivity of these turtles to ARs was assessed using both in vivo and in vitro approaches. We administered 4 mg/kg of warfarin sodium either orally or intravenously to juvenile green sea turtles. The turtles exhibited slow pharmacokinetics, and prolongation of prothrombin time (PT) was observed only with intravenous warfarin administration. We also conducted an in vitro investigation using liver microsomes from green sea turtles, and two other turtle species (softshell turtle and red-eared slider) and rats. The cytochrome P450 metabolic activity in the liver of green sea turtles was lower than in rats. Additionally, vitamin K epoxide reductase (VKOR), which is the target enzyme of ARs, was inhibited by warfarin in the turtles at lower concentration levels than in rats. These data indicate that turtles may be more sensitive to ARs than rats. We expect that these findings will be helpful for sea turtle conservation following accidental AR-broadcast incidents.
The diet of red-eared turtle shifted gradually from insect to plant material with increasing plastron length, and paralleled a habitat shift from feeding sites in shallow to deep water. Basking perches used by small turtles were narrower, more steeply sloped, and located in shallower water than those used by large turtles.-from Author
Food and feeding strategies were examined in two populations of Graptemys pseudogeographica ouachitensis. Diets were determined from examination of entire digestive tracts. Mississippi River specimens are opportunistic feeders, consuming whatever foods become available to them in their barren, inorganic habitat. Diets are supplemented in high-water periods with normally terrestrial vegetation and insects which become accessible. Vegetation becomes more important in the diet as Mississippi River turtles become larger. Meredosia Lake specimens of all sizes are more restricted in diet, mainly consuming locally abundant midge larvae (Chironomidae) throughout the summer of study.
The population sizes, densities, and food habitats of four freshwater turtle species inhabiting a sluggish stream at Chan Chen Junction, Corozal District, Belize, were investigated from January through April, 1984. Population estimates in January indicated that Trachemys scripta was most abundant and reached the highest density, followed by Kinosternon scorpioides, K. leucostomum, and Staurotypus triporcatus. Population estimates in April indicated little change in population size or density of T. scripta or S. triporcatus, but significant increases in numbers and densities of K. scorpioides and K. leucostomum. The increases probably reflect movement into the stream from nearby ephemeral habitats that dried during the prolonged spring dry season. Adult T. scripta of both sexes foraged throughout the stream and were primarily herbivorous, whereas juveniles were restricted to dense mats of vegetation along stream margins and were insectivorous. Adult K. scorpioides and K. leucostomum were ubiquitous and primarily insectivorous but their dietary similarity decreased as population sizes increased. Staurotypus foraged throughout the stream on large gastropods and turtles, the latter increasing in importance as the kinosternid population increased.
