Literaturdatenbank
Literaturdatenbank |
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Mosimann, D., & Cadi, A. (2004). On the occurrence and viability of the european pond turtle (emys orbicularis) in moulin-de-vert (geneva, switzerland): 50 years after first introduction. Biologia (Bratislava), 59(Suppl. 14), 109–112.
Added by: Admin (06 Jan 2014 18:23:00 UTC) |
| Resource type: Journal Article BibTeX citation key: Mosimann2004 View all bibliographic details  |
Categories: General Keywords: Emydidae, Emys orbicularis, Europa - Europe, Habitat - habitat, invasive Arten - invasive species, Schildkröten - turtles + tortoises, Trachemys scripta Creators: Cadi, Mosimann Collection: Biologia (Bratislava) |
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| Abstract |
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This investigation was aimed: (i) to survey a mixed population of allochthonous Emys orbicularis and Trachemys scripta elegans in the Moulinde- Vert reserve (Canton of Geneva, SW Switzerland) 50 years after introduction of the first E. orbicularis, and (ii) to study the habitat use by E. orbicularis there. We used three methods: visual observations, the capturemark- recapture method, and nesting observations. 1,439 observations were carried out between 11 April and 19 October 2001. The most significant climatic data impacting the observations are the average duration of sunshine and its intensity. The very most observation data refer to E. orbicularis; less than 5% of observations refer to T. s. elegans. Only six T. s. elegans were captured and removed. All age classes of E. orbicularis were recorded, however, adults predominated (89% of the observations). Younger age classes are shyer and more cryptic. This could have led to an underestimation of their number. The adult sex-ratio was skewed in favour of females (1 male : 1.47 female). Deadwood was the preferred basking site (nearly three-quarters of observations). A highly efficient trapping method was applied, leading to the capture of 462 pond turtles in four sessions, representing a total of 260 individuals. The highest capture numbers were obtained in summer. During the pre-nesting capture session (14–18 May), males dominated, indicating their increased activity during the reproductive season. Females were more abundantly caught during the other capture sessions (post-nesting: 2–6 July; summer: 13–18 August; pre-hibernation: 10–14 September). Greater numbers of subadults and juveniles were recorded from the beginning of summer to the end of September and after the hatching season in October. We estimate the population size to be 306 ± 10.5 turtles. This corresponds to a density of 64 individuals per hectare.
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