Review of puma density estimates reveals sources of bias and variation, and the need for standardization

Abstract

Range-wide status assessments of wildlife are critical to effective species conservation and management. Reliability of these assessments is contingent on having accurate and precise demographic estimates for local populations, but for large carnivores, such estimates are often biased, imprecise, or unavailable. Despite being the most widely distributed large carnivore in the Americas, little is known about the range-wide population status of the puma (Puma concolor). Population density is frequently the primary demographic metric used in puma conservation and management decision-making and policy; therefore, we conducted a comprehensive, range-wide, systematic review of capture-recapture and mark-resight model-based puma density estimates published through 2021 and used Bayesian multilevel models to investigate potential sources of bias and variation. Model-based puma density estimates have been produced in just 8 countries (42% of countries with puma populations) for study areas that cumulatively represent 0.20) and likely positively biased, primarily because of small study area sizes and issues associated with some sampling and analytical methods; for example, we observed a potential 31–33% overestimation of puma density when spatially unstructured genetic sampling was used. Consequently, the quality of many existing model-based puma density estimates may be inadequate for reliable conservation or management decision-making, and the current number and geographical extent of puma density estimates are likely insufficient to inform useful continental or range-wide status assessments for the species.

Keywords

• Capture-recapture
• Cougar
• Density estimation
• Mark-resight
• Mountain lion
• Puma concolor