By Trachemys Scripta: Concerns for Native Avifauna in the Non-Native Range of This Widely Established Turtle?
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Herpetology Notes, volume 14: 45-48 (2021) (published online on 08 January 2021) Predation of a live duckling (Anas platyrhynchos) by Trachemys scripta: concerns for native avifauna in the non-native range of this widely established turtle? Andrés Pérez Salerno1,* and Matthijs P. van den Burg2 Pond Sliders, Trachemys scripta (Thunberg in The impact of nonnative Trachemys scripta populations Schoepff, 1792), are among the widest-spread animal on native species and ecosystems has been addressed species outside their native range (TTWG, 2017). by several studies. Namely, they can compete for food, Mainly through the international pet trade this species basking sites, and nesting sites, and thereby displace has been introduced to at least 76 countries and all native turtle species (Cadi and Joly, 2003; Cadi et al., continents but Antarctica (TTWG, 2017). In addition, 2004; Pérez-Santigosa et al., 2008, 2011; Ficetola et al., habitat suitability modelling has demonstrated that the 2009; Vamberger, 2009; Crescente et al., 2014; Pearson current range of this species can expand even further et al., 2015; Standfuss et al., 2016). Additionally, Pond (Rödder et al., 2009; Rodrigues et al., 2016; Espindola Sliders are known to harbour pathogens and parasites et al., 2019). (Rataj et al., 2011; Shen et al., 2011) whose spread into In Europe, successful reproduction has been reported ecosystems and populations of native freshwater turtles from several mainly southern locations: France, Greece, is feared (Meyer et al., 2015; Demkowska-Kutrzepa et Italy, Portugal, Slovenia, and Spain (Martínez-Silvestre al., 2018). Native Slider populations have been shown et al., 1997; Cadi et al., 2004; Bruekers et al., 2006; to impact the functioning of freshwater ecosystems, Pérez-Santigosa et al., 2008; Crescente et al., 2014; directly affecting factors such as pH, conductivity, Standfuss et al., 2016; Martins et al., 2018). However, sediment accumulation, leaflitter decomposition and winter survival of adults and successful reproduction the abundance of macro-invertebrates (Lindsay et al., have also been reported from more northerly areas: 2013). These potential impacts should be assessed for Austria, Germany, and in Switzerland (Wüthrich, 2004; nonnative populations as well. Pieh and Laufer, 2006; Kleewein, 2014; Schradin, Several dietary studies assessed the stomach and/or 2020). Moreover, its Eurasian range is even larger: intestine content of Slider populations, both from the e.g., presence in Bulgaria, Denmark, Finland, Latvia, native range (Pierce, 1992; Dreslik, 1999; Stephens and Netherlands, Poland, Russia, and Sweden (Najbar, Ryan, 2019) and from the non-native range (Prévot- 2001; Herder, 2007; Pupins, 2007; Semenov, 2010; Julliard et al., 2007; Outerbridge, 2008; Lee and Park, Tzankov et al., 2015; TTWG, 2017). Indeed, as the 2010; Pérez-Santigosa et al., 2011; Wang et al., 2013; climate warms the range of T. scripta is also expected to Works and Olson, 2018). These identify both native and increase, and successful reproduction will likely occur non-native populations as omnivorous, with different in more northern areas (Banha et al., 2017; Spear et al., life stages having different diets; for example, smaller 2018; Espindola et al., 2019). Sliders are more carnivorous, whereas adults are more herbivorous. Animal foods mainly consist of a wide range of insects (mainly Notonectides, Coryxides, and Odonates), crustaceans, mollusks, and fish. Frogs and reptiles are also occasionally reported in the diet (e.g., 1 Independent biologist, Valencia, Spain. 2 Department of Biogeography and Global Change, Museo Outerbridge, 2008; Ma and Shi, 2017; Works and Olson, Nacional de Ciencias Naturales (MNCN), Consejo Superior 2018), as are occasional bird remains (Pierce, 1992; de Investigaciones Científicas (CSIC), C/ José Gutiérrez Outerbridge, 2008; Pérez-Santigosa et al., 2011; Wang Abascal 2, 28006 Madrid, Spain. et al., 2013; Ma and Shi, 2017). However, it is usually * Corresponding author. E-mail: [email protected] assumed that the latter originated from feeding on © 2020 by Herpetology Notes. Open Access by CC BY-NC-ND 4.0. carcasses (Martínez-Silvestre et al., 2015 and references 46 Andrés Pérez Salerno & Matthijs P. van den Burg therein), similar to scavenging by other turtles on other characteristics. However, diagnostic features (e.g., vertebrates (Lindeman, 2000; Burroughs et al., 2014). feathers, teeth, scales, bones, or exoskeletal parts) are A literature review (following van den Burg [2020]) often unidentifiable, or might not be present. Hence, we indicated observations of Trachemys scripta depredating argue that to better understand the occurrence, frequency living birds or other live vertebrates are rarely reported, and diversity of prey in future dietary studies of although Ligon (2007) documented predation of a Red- Trachemys scripta (and other taxa), genetic techniques winged Blackbird by a Pond Slider, and Pritchard and should be applied (Carreón-Martínez et al., 2011). Trebbau (1984) reported predation on waterfowl by T. s. callirostris, now T. venusta callirostris (Uetz et al., Acknowledgements. We thank John Iverson for providing 2020). comments and edits on an earlier version of this manuscript. On 25 June 2020 at 14:00 h, air temperature of 25 – 30 ºC, APS toured the Cabecera Park in Valencia, References Spain (39°28’42.7”N, 0°24’33.2”W). While observing Banha, F., Gama, M., Anastácio, P.M. (2017): The effect of the birds that inhabited the lake, he noticed an unusual reproductive occurrences and human descriptors on invasive pet movement in the water. Approaching rapidly, he distribution modelling: Trachemys scripta elegans in the Iberian observed as an adult female Trachemys scripta (>25 cm Peninsula. Ecological Modelling 360: 45–52. carapace length) come up through the water column, Bruekers, J., Uijtterschout, G., Brouwer, A. (2006): grab a duckling (Anas platyrhynchos) from the water Erstnachweis einer natu¨rlichen Vermehrung der Rotwangen- surface and submerge with its prey in its mouth. The Schmuckschildkröte (Trachemys scripta elegans) auf der attack lasted just seconds, and so the only photograph griechischen Insel Kos. Schildkröten im Fokus 3: 29–34. Burroughs, R.W., Morris, Z.S., Marsh, A.D. (2014): Trachemys that could be taken showed only the shape of the turtle scripta (Red-eared Slider), Pseudemys texana (Texas River disappearing in the cloudy water. Thereafter, APS spent Cooter), Chelydra serpentina (Snapping Turtle). Feeding >15 minutes in the area, but did not see the turtle nor its behavior and scavenging. Herpetological Review 45: 321–322. duckling prey. Cadi, A., Joly, P. (2003): Impact of the introduction of the Red- As noted above small birds and other vertebrates have eared Slider (Trachemys scripta elegans) on survival rates of frequently been identified in stomach and/or intestine the European Pond Turtle (Emys orbicularis). Biodiversity & samples of Trachemys scripta. The relatively small Conservation 13: 2511–2518. maximum size of this species (to ca. 30 cm carapace Cadi, A., Delmas, V., Prévot-Julliard, A.-C., Joly, P., Pieau, C., length) and its scavenging behaviour suggest that its Girondot, M. (2004): Successful reproduction of the introduced Slider Turtle (Trachemys scripta elegans) in the south of France. predation of live vertebrates, other than small fish and Aquatic Conservation: Marine and Freshwater Ecosystems 14: amphibians, is unlikely (but see Parmenter and Avery 237–246. [1990], Ligon [2007], and Struijk and van den Sanden Carreón-Martinez, L., Johnson, T.B., Ludsin, S.A., Heath D.D. [2018]). Indeed, in a dietary study on a nonnative Slider (2011): Utilization of stomach content DNA to determine diet population in France, Prévot-Julliard et al. (2007) diversity in piscivorous fishes. Journal of Fish Biology 78: argue the public wrongly believes that Sliders “could 1170–1182. even attack small young ducks (public information)”. Crescente, A., Sperone, E., Paolillo, G., Bernabò, I., Brunelli, E., Confirmingly, the only reported vertebrate prey in their Tripepi, S. (2014): Nesting ecology of the exotic Trachemys scripta elegans in an area of southern Italy (Angitola lake, visual dietary study was fish, and the larger fish scales Calabria). Amphibia-Reptilia 35: 366–370. were suspected to have been scavenged (Prévot-Julliard Demkowska-Kutrzepa, M., Studzińska, M., Roczeń-Karczmarz, et al., 2007). On the contrary, Ligon’s (2007) and our M., Tomczuk, K., Abbas, Z., Rózański, P. (2018): A review of observation demonstrate that predation on live birds the helminths co-introduced with Trachemys scripta elegans – a does occur. We believe that the speed with which these threat to European native turtle health. Amphibia-Reptilia 39: events seemingly occur, as well as that the prey is taken 177–189. underwater, greatly decrease the chances of directly Dreslik, M.J. (1999): Dietary notes on the Red-eared Slider observing them. Therefore, from a biological invasion (Trachemys scripta) and River Cooter (Pseudemys concinna) perspective, the current effect of established and large from southern Illinois. Transactions of the Illinois State Academy of Science 92: 233–241. populations of non-native Trachemys scripta on the Espindola, S., Parra, J.L., Vázquez-Domínguez, E. (2019): native vertebrate fauna inhabiting aquatic ecosystems Fundamental niche unfilling and potential invasion risk of the may be underestimated. slider turtle Trachemys scripta. PeerJ 7: e7923. The correct visual identification