IUCN richness maps
We developed a range of maps of richness using different techniques
outlined here. Firstly, as a comparator we mapped richness using IUCN
polygons as well as trimming the IUCN polygons as advocated by Brooks et
al 2019. To map richness of African bats based on the IUCN (though this
does not include all known species) we downloaded as all Chiroptera from
the African continent from the IUCN website (on June 3rd). Firstly we
clipped the polygons for a rectangular area over the African continent,
then dissolved each species polygon to give a single polygon for each
species. We used the “count overlapping polygons” toolbox, split the
polygon. To do this we split the polygon into groups of 30 species (the
tool works better on lower numbers), numbered outputs sequentially, then
converted to rasters (with a resolution of 0.008 degrees, approximately
1km at the equator) then used the raster calculator to add all results
to map richness according to the IUCN.