Special Section: Hierarchical Models in Avian Ecology

As spatial ecology, biogeography, and landscape ecology progress we are increasingly aware of how spatial and temporal scale structure ecological patterns and affect ecological processes (Wiens 1989). Advances in these fields have come from studies of a variety of taxa, particularly plants and insects (With 1994, Ludwig and Tongway 1995, Wondzell et al. 1996, McIntyre and Wiens 1999, Östman and Ives 2003), but avian studies have also been influential and compelling. Scale dependence is found in bird movement patterns (Fritz et al. 2003), foraging ecology (Hinsley 2000), and habitat associations (Cushman and McGarigal 2002). The models we use to understand ecological systems should be compatible with the structure of the systems themselves (Maurer 2002), thus scale-dependent patterns should be explicitly explored. This special section was inspired by a symposium on hierarchical approaches to studying avian ecology at the 2004 Cooper Ornithological Society meeting in La Crosse, WI. The La Crosse symposium, in turn, was inspired by the publication of Scott et al. (2002) ‘‘Predicting Species Occurrences: Issues of Accuracy and Scale.’’ This compendium of concepts and methods for predicting species occurrence contained many exciting, promising advances in the art and science of modeling bird-habitat associations. It also contained disconcerting signs that we are not yet adequately dealing with the ecological and statistical problems that face us in this field. The first sign of trouble is that although habitat models are sometimes impressively predictive, often they are not (Wiens 2002). Predictive inaccuracy is a complex issue that conflates biological, methodological, and statistical problems, but predictive accuracy is a gold standard in science and the poor predictive power of habitat models is cause for concern. We currently have a vast array of statistical approaches available to apply to habitat modeling, including approaches that have only recently been practical due to heavy computational requirements (Stauffer 2002). Unfortunately, it is not clear that lack of statistical complexity or sophistication is the root of the problem (Huston 2002). Although technical advances may improve our ability to sample animals in the field, and to apply complex statistical models to their habitat associations, the greater need is to appropriately match statistical approaches with ecological structure (Maurer 2002, O’Connor 2002). It is natural, in light of this need, to explore the use of hierarchical statistical models in avian ecology. The first paper in this special section points out that although ‘‘scale-dependent’’ is not synonymous with ‘‘hierarchical’’, there are reasons to suspect that hierarchical patterns should be common both in habitats and in bird responses to habitats (Kristan 2006). HierarManuscript received 26 January 2005; accepted 30 October 2005. 1 Present address: Department of Biological Sciences, California State University, San Marcos, CA 92096. E-mail: [email protected]