Where have all the lions gone? Establishing realistic baselines to assess decline and recovery of African lions

Aim: Predict empirically the current and recent historical (c1970) landscape connectivity and population size of the African lion as a baseline against which to assess conservation of the species. Location: Continental Africa. Methods: We compiled historical records of lion distribution to generate a recent historical range for the species. Historical population size was predicted using a generalized additive model. Resistant kernel and factorial least-cost path analyses were used to predict recent historical landscape connectivity and compare this with contemporary connectivity at continental, regional and country scales. Results: We estimate a baseline population of ~92,054 (83,017–101,094 95% CI) lions in c1970, suggesting Africa's lion population has declined by ~75%, over the last five decades. Although greatly reduced from historical extents (c1500AD), recent historical lion habitat was substantially connected. However, in comparison, contemporary population connectivity has declined dramatically, with many populations now isolated, as well as large declines within remaining population core areas. This decline was most marked in the West and Central region, with a 90% decline in connected habitat compared with its c1970 extent. The Eastern and Southern regions have experienced lower, though significant, declines in connected habitat (44% and 55%, respectively). Contemporary populations are connected by three non-core habitat linkages and 15 potential corridors (spanning unconnected habitat) that may allow dispersal and gene flow. Declining connectivity mirrors recent studies showing loss of genetic diversity and increasing genetic isolation of lion populations. Main conclusions: We provide an empirically derived baseline for African lion population size, habitat extent and connectivity in c1970 and at present against which to evaluate contemporary conservation of the species, avoiding a shifting baseline syndrome where conservation success/failure is measured only against recent population size or range. We recommend priorities for conservation of existing connections to avoid further fragmentation.