Towards effective and harmonized lion survey methodologies: a systematic review of practice across Africa

Understanding the population status of a species is vital for their conservation. Over the last two decades, multiple methods for surveying lion (Panthera leo) populations have been designed and tested. Each have strengths and weaknesses, with different applications, and varying levels of reliability, accuracy and precision. We conducted a PRISMA systematic review to identify and assess survey methods for estimating lion population abundance. We searched the Web of Science and Google Scholar for peer reviewed papers between January 1991 and December 2022. Sixty-five papers were included, with some using multiple methods or multiple study sites; when these were separated, 93 studies were identified. Seven broad population survey methods for lions were identified: call ups (34.8% of studies), spoor counts (32.5%), direct observations (15.7%), direct observations with capture recapture elements (12.4%), camera trap-based capture-recapture analysis (4.5%), genetic surveys (3%) and distance-based surveys (1.1%). Our literature review suggests that the most reliable methods for determining lion density or abundance are direct observations and camera trap-based capture recapture surveys. Genetic surveys combined with spatially-explicit capture recapture analysis also hold significant potential. Due to their lack of reliability and tendency to over-estimate populations, call ups and spoor counts are not recommended for determining population abundance. We further recommend that harmonized methods be developed that can produce comparable and reliable estimates, which can be used to inform conservation decisions across the species range.