STUDY DESIGN AND INTERPRETATION OF MAMMALIAN CARNIVORE DENSITY ESTIMATES

Ecological theory and wildlife management often depend on reliable com parison and interpretation of population density estimates. A synthesi s of 1,772 mammalian carnivore population estimates (713 unique to ref erence, species, site, and size of study area) from 74 species reveale d global patterns among aspects of study and interpretive design that undermine the reliability and usefulness of density comparisons. The s patial extent of the study area could explain most of the variation in density, probably because study areas are typically delineated around population clusters. We related the scale-defined density estimates ( regression residuals) to 28 other variables measured from the publishe d literature, but none provided convincing biological explanation of t he variation in density. Many aspects of study and interpretive design were possibly ill-suited to identifying the factor(s) influencing den sity. Study attributes and findings were reported inconsistently. and were subject to ideological motivations. Descriptions of vegetation we re most difficult to relate to density. More intensive sampling and es timation methods produced above-average density estimates, but the dif ferences were slight and the evidence lacking for concluding whether t hese more intensive methods were also more accurate. The first underly ing factor extracted from principle-components analysis described the growing recognition of population declines and range reductions among large-bodied carnivores, which has also influenced study design. Anoth er factor described an increasing trend for density to be compared and extrapolated to larger areas, but without adjusting for the effect of scale. To understand the factors influencing carnivore distribution a nd abundance, sampling and reporting methods (e.g., site description w ith maps) will need to represent the available pool of species, locati ons, and ecological conditions at larger-than-conventional spatial and temporal scales.