E. orbicularis is found insouthern,central, andeasternEurope,West Asia and parts ofMediterraneanNorth Africa. InFrance, there are six remaining populations of significant size; however, they appear to be in decline. This turtle species is the most endangered reptile of the country.[5] InSwitzerland, the European pond turtle was extinct at the beginning of the twentieth century but reintroduced in 2010.[5] In theearly post-glacial period, the European pond turtle had a much wider distribution, being found as far north as southernSweden andGreat Britain,[6] where a reintroduction has been proposed by theStaffordshire-basedCeltic Reptile & Amphibian, a group specialising in the care, research, and rehabilitation of native European and Britishherpetiles.[7] A trial reintroduction has been initiated, restoring the species back to its Holocene-nativeEast AnglianFens,Brecks andBroads.[8] In 2004, the European pond turtle was found in the Setomaa region ofEstonia.[9]
Fossil evidence shows thatE. orbicularis andTestudo hermanni were both present inSardinia during the Pleistocene, but molecular evidence suggests the extant populations of both species on the island wereintroduced in modern times.[10]
A group of European pond turtles in the remnants of the Roman baths inButrint,Albania
E. orbicularis prefers to live inwetlands that are surrounded by an abundance of lush, wooded landscape. They also feed inupland environments.[11] They are usually considered to be only semi-aquatic (similar to Americanbox turtles), as their terrestrial movements can span 1 km (0.62 mi). They are, occasionally, found travelling up to 4 km (2.5 mi) away from a source of water.[11]
The European pond turtle is a medium-sized turtle, and its straightcarapace length varies quite a bit across its geographic range, from 12 to 38 cm (4.7 to 15.0 in). The carapace is dark brown to blackish, with a hint of green. The head and legs are spotted with yellow. Theplastron is yellowish.
An important factor that affects the development ofE. orbicularis is temperature and thermal conditions. It has been reported that differential growth rates of the same species occur, including variation of body size andclutch size, because of varying temperatures in certain areas.[12] Due to evident patterns ofsexual dimorphism,E. orbicularis adult males are always found to be smaller than females. In males, smallerplastra offer them a wider mobility compared to females. In females, due to their differential diet and foraging habits, there may be a correlation to an adaptive effect on their skull and head morphology.[12]
E. orbicularis eats a mixed diet of plants and animal matter that can increase the efficiency of its digestive process.[11] It has been reported that an adult's diet starts from a carnivorous diet and progresses to a moreherbivorous diet as it ages and grows in size. This is similar to other omnivoreemydid turtles.[11] AsE. orbicularis grows in age and becomes an adult, the amount of plant material consumption increases during the post breeding period.E. orbicularis may prefer less energetic food after the breeding season, a period of time where most of its energy is spent to recover from reproduction.[11]
Most freshwater turtles lay their eggs on land, typically near a water source, but some species ofEmys have been found to lay their eggs no less than 150 m (490 ft) from water.[3] The search for nesting areas, by adult females, can last several hours to several days. Once an appropriate site is found, females take their time with the construction of the nest, painstakingly excavating a small pit out of the soft substrate purely by usage of her small forelimbs. Once satisfied with the depth of the nest, she will turn around (facing away from the nest) and proceed with egg-laying, gently dropping the eggs down and into a small pile. This process varies in duration; laying can take merely half an hour or upwards of several hours, depending on weather, interference by other animals, humans, etc. When laying is complete (and still facing away from the nest), the female turtle will use her back limbs this time, to cover and close the nest. This is another variable routine which can take up to another four hours.[13]
Nest fidelity is a characteristic that is unique to female European pond turtles—selecting a nesting site based on its ecological characteristics—and then returning there for future laying, so long as the site has not changed.[3]E. orbicularis females tend to look to a new nesting site if there are visible changes to the original nest’s surroundings, or because of dietary and metabolic changes. If anE. orbicularis female must change from nest to nest, she will typically select a site in relatively close proximity.[3] In addition, females may also lay eggs in an abandoned nesting site if the conditions are an improvement, and deemed to be better suited for egg survival. If the environmental conditions of a nesting site change, this may influence the development of the eggs, the survival of the hatchlings and/or their sex ratio. Due to unforeseen ecological changes, such as thick vegetation growing over a season (and blocking sun to the nest), a nest site may become inadequate for incubating eggs. Females that do not exhibit nesting fidelity, and continue to lay in the same area for long periods of time—even with the ecological changes—may end up producing more male offspring, as the cooler and darker conditions promote more males developing.[3] Since the sex of these turtles is temperature-dependent, a change in temperature may produce a larger number of males or females which may upset the sex ratio.[3]
Climate has an effect on the survival ofE. orbicularis hatchlings. Hatchlings are only able to survive under favorable weather conditions, but due to regular annual clutch sizes and long lifespan,E. orbicularis adults, along with many freshwater turtles, balance out loss of hatchlings due to climate.[13]
The speciesE. orbicularis has become rare in most countries even though it is widely distributed in Europe. The building of roads and driving of cars through natural habitats is a possible factor that threatens the populations of the European pond turtle. Road networks and traffic often carry complex ecological effects to animal populations such as fragmenting natural habitats and creating barriers for animal movement. Mortality on the road is most likely due to females selecting nests near roads which places a potential danger for the hatchlings as well. Hatchlings that wander too closely to roads are more likely to be killed and put the future population in danger. Although the possibility of roads being a major causation for the mortality ofE. orbicularis is a rare phenomenon, long-term monitoring is necessary.[13]
Introduced exotic species such asTrachemys scripta scripta andT. s. elegans, knowncommonly asFlorida turtles, also put in danger the nativeEmys species in many parts ofSpain (and possibly in other parts of southern Europe), since these exotic turtles are bigger and heavier than the native pond turtles.[14][15] The usual life span ofE. orbicularis is 40–60 years. It can live over 100 years, but such longevity is rare.
Historically,E. orbicularis had been maintained as pets; however, this practice has been restricted due to protection laws. Ownership of wild caught specimens is prohibited. Only registered captive bred specimens may be owned by private individuals. Due to human impact, the European pond turtle has been found to be relocated in areas distant from its origin. However, it is possible to localize and indicate a region of origin withgenetic testing.[16]
^abcdefMitrus, Sławomir (2006). "Fidelity to nesting area of the European pond turtle,Emys orbicularis (Linnaeus, 1758)".Belgian Journal of Zoology.136 (1):25–30.
^abZuffi, M. A. L.; Celani, A.; Foschi, E.; Tripepi, S. (2007). "Reproductive strategies and body shape in the European pond turtle (Emys orbicularis) from contrasting habitats in Italy".Italian Journal of Zoology.271 (2):218–224.doi:10.1111/j.1469-7998.2006.00212.x.
^abcTrakimas, G.; Sidaravicius, J. (2008). "Road mortality threatens small northern populations of the European pond turtle,Emys orbicularis".Acta Herpetologica.3 (2):161–166.
Arnold EN,Burton JA (1978).A Field Guide to the Reptiles and Amphibians of Britain and Europe. (With 351 illustrations, 257 in colour byD.W. Ovenden). London: Collins. 272 pp. + Plates 1-40.ISBN0-00-219318-3. (Emys orbicularis, p. 93 + Plate 14, figure 1 + Map 48).
Boulenger GA (1889).Catalogue of the Chelonians, Rhynchocephalians, and Crocodiles in the British Museum (Natural History). New Edition. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). x + 311 pp. + Plates I-III. (Emys orbicularis, pp. 112–114).
Linnaeus C (1758).Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio Decima, Reformata. Stockholm: L. Salvius. 824 pp. (Testudo orbicularis, new species, p. 198). (in Latin).
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