Country and international regional boundaries: Natural Earth, version 5.1.2, public domain. UK constituent countries, London and Spanish autonomous communities are grouped from the source areas. Display boundaries are generalized and may differ from current administrative divisions or eBird regions.
United States counties and Puerto Rico municipalities: U.S. Atlas, based on U.S. Census Bureau data.
South African district boundaries: OCHA ROSEA and the South African Municipal Demarcation Board, via geoBoundaries gbOpen ZAF ADM2 (2020 boundaries, release 9469f09). Licensed under CC BY 3.0 IGO. Geometry simplified by the source and rounded for display; districts linked to provinces for this journal. No endorsement is implied.