Journal cover Journal topic
Web Ecology An open-access peer-reviewed journal
Journal topic
Volume 7, issue 1
Web Ecol., 7, 63-76, 2007
https://doi.org/10.5194/we-7-63-2007
© Author(s) 2007. This work is distributed under
the Creative Commons Attribution 3.0 License.
Web Ecol., 7, 63-76, 2007
https://doi.org/10.5194/we-7-63-2007
© Author(s) 2007. This work is distributed under
the Creative Commons Attribution 3.0 License.

  14 Sep 2007

14 Sep 2007

Estimating viability and sensitivity of the great crested newt Triturus cristatus at a regional scale

T. Karlsson1, P.-E. Betzholtz2, and J. C. Malmgren3 T. Karlsson et al.
  • 1Dept. for Nature Conservation, the County Admin. Board of Östergötland, 58186 Linköping, Sweden
  • 2School of Pure and Applied Natural Sciences, Univ. of Kalmar, 39182 Kalmar, Sweden
  • 3JM Natur, Conservation and Restoration Ecology, Baldergatan 48, 69232 Kumla, Sweden

Abstract. Viability and sensitivity of the great crested newt Triturus cristatus were simulated under different scenarios with a demographically and spatially structured stochastic model in an area of 144 km2 in southeastern Sweden. Eighteen ponds were monitored using drift fences with pitfall traps, funnel traps, visual observation and netting during the spring and summer of 2004. Estimated adult population sizes ranged between 0 and 620 individuals and the mean (±SD) local population size was 297 ± 233 individuals. Due to uncertainty of the data, the model was simulated with parameter ranges to estimate upper and lower bounds of viability. Estimated quasi-extinction risk (the risk of each population in the study area falling below 10 females) within a 50-yr period ranged from 100% to 0%, with a “best” estimate of 19.2%. The parameter most sensitive for the model outcome was fecundity, followed by juvenile survival, adult survival and transition from juvenile to adult. When these parameters were set at their lower bound, the quasi-extinction risk increased to 80–100%, while simulating these parameters at their higher bound inferred no or nearly no risk of quasi-extinction. This highlights the importance of focusing conservation efforts and research on the early life cycle stages. Management measures such as restoration of ponds and increased pond density decreased the risk for the great crested newt to end up quasi-extinct in the study area after 50 yr. The results may have implications on management measures of great crested newts throughout its distribution area.

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