Body condition is increasingly used to assess the status of populations and as a proxy for individual fitness. A common, quick and non-invasive approach is to estimate condition from the relation between body length and mass. Among the methods developed for this purpose, the Scaled Mass Index (SMI) appears best suited for comparisons among populations. We assembled data from 17 populations of European green toads (Bufotes viridis) with the aim of devising a standard formula applicable for monitoring this species. The mean value of the exponents describing length-mass allometry in these samples was 3.0047. Hence, we propose using 3 as a scaling coefficient for calculating the SMI in green toads. From the contrast of SMI values for both sexes within populations, estimated with either the population-specific or the standard coefficient, we conclude that applying the standard formula not only facilitates comparisons among populations but may also help to avoid misinterpretation of variation within populations.

Department of Biology AG Zoology Institute of Integrated Sciences University of Koblenz Landau 56070 Koblenz Germany

Department of Ecology and Environmental Conservation Faculty of Biology University of Plovdiv Paisii Hilendarski 24 Tzar Assen Str 4000 Plovdiv Bulgaria

Department of Evolutionary Biology University of Vienna Djerassiplatz 1 1030 Vienna Austria

Department of Game Management and Wildlife Biology Faculty of Forestry and Wood Sciences Czech University of Life Sciences Prague Kamýcká 129 165 00 Prague Czech Republic

Department of Human Anatomy and Physiology Faculty of Biology University of Plovdiv Paisii Hilendarski 24 Tzar Assen Str 4000 Plovdiv Bulgaria

Independent Researcher Ebenreuth 47 94169 Thurmansbang Germany

Institute of Zoology University of Natural Resources and Life Sciences Gregor Mendel Straße 33 1180 Vienna Austria

Landesbund für Vogelschutz in Bayern e 5 Kreisgruppe München Klenzestr 37 80469 München Germany

Landschaftserhaltungsverband Landkreis Ravensburg e 5 Frauenstr 4 88212 Ravensburg Germany

Museum and Institute of Zoology Polish Academy of Sciences Wilcza 64 00 679 Warszawa Poland

NABU Naturschutzstation Leverkusen Köln Friedrich Ebert Str 49 50996 Köln Germany

Wissenschaftszentrum Weihenstephan für Ernährung Landnutzung und Umwelt der Technischen Universität München Alte Akademie 8 85354 Freising Germany

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