The South African Living Planet Index Shows the Value of a Supposedly ‘Uninformative’ Indicator

ABSTRACT Monitoring the local abundance of wild species is a priority for policy and management. The Living Planet Index (LPI) tracks global trends in the relative abundance of monitored wild vertebrates. However, barring a few exceptions, the LPI's uptake at the national level has been limited. Prominent critiques have not helped the perception that the LPI and its underlying database are inadequate for national application. After developing a national LPI for South Africa, we assert that the process of developing the index is valuable and information‐rich, even if the resulting indicator itself is likely of limited accuracy. Specifically, we first calculated three versions of the LPI by applying different weightings to account for taxonomic biases. This demonstrated how incomplete and biased data clouded our ability to determine abundance trends accurately. Next, we recalculated the LPI after supplementing the global database with high‐quality information from a long‐term aerial census of mammal herbivores. Adding these high‐quality time‐series had little effect on the LPI, suggesting that the index is less sensitive to the quality of time‐series for well‐studied taxa than to additional information from poorly studied taxonomic groups. The uncertainties around the South African LPI preclude any confident statements about the average trends in abundance, yet they shine a bright spotlight on knowledge gaps that should be the focus of prioritized monitoring. Therefore, we advocate for other countries to develop their own national LPIs, which are valuable indicators of the state of knowledge (or ignorance) on the abundance of wild species.