Extended Data Fig. 1: Routes surveyed during four road transect studies.

These were conducted during 1969–1977 and 2000–2020 in northern Cameroon, Kenya, Burkina Faso, Niger and Mali, and during 1991–1995 and 2015–2016 in northern Botswana. Panels adapted with permission from: Burkina Faso, Niger and Mali, ref. 40, Wiley; northern Cameroon, ref. 41, Allen Press; Kenya, ref. 42, Elsevier; northern Botswana, ref. 43, Elsevier.