The factors influencing patterns of black bear (Ursus americanus) abundance must be understood to conserve the species, but understanding these factors depends on study design. I synthesized reported estimates of black bear density to (1) test if 28 corresponding study attributes could explain the variation in density, and (2) identify biases and information shortfalls impeding research effectiveness. Most of the variation in 29 estimates of density was explained by the size of study area, or alternatively, by the number of bears captured/km2. Density decreased with increasing size of study area, it increased with the number of captured bears/km2, and it decreased with longer duration of study. The regression models predicted 20 to 52 bears in a 1-km2 area, indicating that study area boundaries have been consistently delineated around bear aggregations. Study design can be improved to more effectively explain the variation in black bear density and relate it to other useful information. Important improvements could include: (1) extending the sampling area across larger geographic areas using sign counts; (2) choosing study sites randomly or systematically across black bear ranges; (3) extending population studies over longer time periods; and, (4) consistently measuring and reporting population and site attributes for future synthesis
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