ABSTRACT
The geographical element of conservation planning is fundamental to conservation decision making, with maps constituting a critical communication and visualization tool. However, their constraints and assumptions are not immediately obvious, and the impact of the choice of method or scale is rarely considered or discussed. To elucidate the utility of geostatistical (semivariography and kriging) and geographic information systems (GIS)-based visualization (inverse-distance weighting [IDW] and three-dimensional [3-D] vertical extrusion plots), we used these approaches to visualize broad-scale breeding distributions for four bird species. Our findings suggested that each of the methods revealed different but complementary aspects of spatial distribution. IDW was somewhat sensitive to the size of the spatial neighborhood and variation in this parameter highlighted the potential role of different environmental factors operating at different spatial scales. Kriging assumptions were, at best, only weakly met, but in the case of the American robin (Turdus migratorius) it highlighted similar patterns to IDW. Despite a limited ability to convey underlying trends, 3-D extrusion plots allowed for the easy identification of locations of unusual abundance or geographic isolation. In summary, we expect that conservation planners will be especially interested in applying these methods to identify core areas of peak abundance, thereby assisting conservation prioritization. Additionally, these methods have a critical role to play in hypothesis generation, with the potential to identify important driving factors.
