Bias in estimation of newt population size: a field study at five ponds using drift fences, pitfalls and funnel traps

Weddeling, Klaus and Hachtel, Monika and Sander, Ulrich and Tarkhnishvili, David (2004) Bias in estimation of newt population size: a field study at five ponds using drift fences, pitfalls and funnel traps. The Herpetological Journal, 14. pp. 1-7. ISSN 0268-0130

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Abstract

Drift fences are frequently used to sample amphibians for population studies. Thus, some researchers do not mark animals, but use capture rates at the drift fence as an indicator of population size. Other workers use mark-recapture techniques to estimate population sizes. These approaches require different amounts of effort and lead to different results. Our study compares several estimates of population size for alpine newts (Triturus alpestris) and smooth newts (Triturus vulgaris) in five breeding ponds surrounded by permanent drift fences and pitfall traps. The estimates based on mark-recapture techniques (Petersen method) do not vary substantially between the two modes of recapture applied (funnel traps, and drift fences with pitfall traps). These estimates give even better results than simple counts if a substantial part of the newt populations remain within the drift fences throughout the year. While unrecognized trespass by newts appears to be a rare event, some newts may leave a pond for a short time even during the breeding season. This is an important source of bias for population estimates in studies based on counts at drift fences when animals are not marked.

Item Type:	Article
Subjects:	Q Science > Conservation Biology Q Science > Ecology Q Science > QL Zoology
Divisions:	Institutes > Institute of Ecology
Depositing User:	Prof. David Tarkhnishvili
Date Deposited:	25 Jan 2014 08:14
Last Modified:	25 Jan 2014 08:14
URI:	http://eprints.iliauni.edu.ge/id/eprint/500

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