Ecologia

Diversity and Distributions, (Diversity Distrib.) (2007) 13, 397–405
Blackwell Publishing, Ltd.

BIODIVERSITY RESEARCH

A comparative evaluation of presenceonly methods for modelling species distribution
Asaf Tsoar*, Omri Allouche, Ofer Steinitz, Dotan Rotem and Ronen Kadmon

Department of Evolution, Systematics and Ecology, Institute of Life Sciences, The Hebrew University of Jerusalem,Campus Edmond Safra, Jerusalem 91904, Israel

ABSTRACT

*Correspondence: Asaf Tsoar, Department of Evolution, Systematics and Ecology, Institute of Life Sciences, The Hebrew University of Jerusalem, Campus Edmond Safra, Jerusalem 91904, Israel. Tel.: 972 26586080; Fax: 972 26584655; E-mail: tsoarasaf@pob.huji.ac.il

In spite of increasing application of presence-only models in ecology andconservation and the growing number of such models, little is known about the relative performance of different modelling methods, and some of the leading models (e.g. GARP and ENFA) have never been compared with one another. Here we compare the performance of six presence-only models that have been selected to represent an increasing level of model complexity [BIOCLIM, HABITAT, Mahalanobis distance(MD), DOMAIN, ENFA, and GARP] using data on the distribution of 42 species of land snails, nesting birds, and insectivorous bats in Israel. The models were calibrated using data from museum collections and observation databases, and their predictions were evaluated using Cohen’s Kappa based on field data collected in a standardized sampling design covering most parts of Israel. Predictive accuracyvaried between modelling methods with GARP and MD showing the highest accuracy, BIOCLIM and ENFA showing the lowest accuracy, and HABITAT and DOMAIN showing intermediate accuracy levels. Yet, differences between the various models were relatively small except for GARP and MD that were significantly more accurate than BIOCLIM and ENFA. In spite of large differences among species in prevalence andniche width, neither prevalence nor niche width interacted with the modelling method in determining predictive accuracy. However, species with relatively narrow niches were modelled more accurately than species with wider niches. Differences among species in predictive accuracy were highly consistent over all modelling methods, indicating the need for a better understanding of the ecological andgeographical factors that influence the performance of species distribution models. Keywords Bats, BIOCLIM, birds, distribution range, DOMAIN, ecological niche models, ENFA, GARP, HABITAT, habitat suitability, Kappa, Mahalanobis distance, predictive maps, prevalence, snails, tolerance.

INTRODUCTION Knowledge about the geographical distribution of species is crucial for conservation and managementof biodiversity (Margules & Pressey, 2000). Yet, for most regions and most taxa, detailed data on species distribution are usually not available and collecting such data is costly and labour intensive (Prendergast et al., 1999; Bowker, 2000; Ottaviani et al., 2004). Consequently, ecologists and conservation scientists increasingly rely on predictive models as a means for estimating patterns ofspecies distribution and informing conservation strategies (Peterson & Robins, 2003; Araujo et al., 2004; Ortega-Huerta & Peterson, 2004; SánchezCordero et al., 2005). The number of methods available for modelling patterns of species distribution is immense (Guisan & Zimmermann, 2000; Scott et al., 2002; Guisan & Thuiller, 2005),
© 2007 The Authors Journal compilation © 2007 Blackwell Publishing Ltdand evaluating the relative performance of different methods remains a continuous challenge in ecology and conservation biology (Loiselle et al., 2003; Thuiller, 2003; Ottaviani et al., 2004; Vaughan & Ormerod, 2005; Elith et al., 2006; Pearson et al., 2006). In general, two categories of methods for species distribution modelling can be distinguished: methods that need presence– absence...