Spatial Data & Mapping Resources

Species Richness and Rarity-Weighted Richness Data

Species Richness and Rarity-Weighted Richness rasters

The rasters available on this page are based on the raw IUCN ranges for amphibians, birds, mammals and, from 2022, reptiles.

The data is biased towards vertebrates as these are currently the terrestrial taxonomic groups that have been comprehensively assessed and for which there are polygon maps. The analyses are only relevant for terrestrial areas, as marine areas will only be represented by birds and mammals.

The analyses available to download from this page are:

Red List version 2024-2

Species Richness
Rarity-Weighted Richness

Red List version 2023-1

Species Richness
Rarity-Weighted Richness

Red List version 2022-2

Species Richness
Rarity-Weighted Richness

Red List version 2021-3

Species Richness
Species Richness and Rarity-Weighted Richness from AoH maps

Red List version 2017-3

Species Richness
Rarity-Weighted Richness

About the Species Richness and Rarity-Weighted Richness analyses

Both analyses are measures of biodiversity calculated for each cell of an equal area grid. This required the ranges to be filtered, for example to exclude ranges where the species is deemed extinct.

Species Richness is a count of the number of species potentially occurring in each grid cell.

Rarity-Weighted Richness is the aggregate importance of each grid cell to the species occuring there. The value does not have any units, but indicates relative importance.

For each species the Rarity-Weighted Richness value for a cell is the proportion of the species' range contained within that cell. This can be the area of the pixel divided by the area of the species' range or (as in these analyses) 1 divided by the total number of cells overlapped by that species' range. These values are summed across all the species in the particular analysis to give the relative importance of each cell to the species found there.

For species with different breeding and non-breeding ranges, where a cell is contained in both ranges, the calculation is based on the smaller range, i.e. the season in which that area is more important.

Input data

These analyses have been performed for two types of input data:

Raw IUCN range polygons
Area of Habitat (AoH) rasters

Raw IUCN range polygons

The raw IUCN ranges for amphibians, birds, mammals and, from 2022, reptiles were intersected with a grid of 865 km² hexagon cells, clipped to the coastline. Marine-only species were excluded from the analyses. As the species ranges have not been refined (for example, by altitude and landcover), there may be a fair amount of unsuitable habitat in the raw ranges, resulting in errors of commission.

Each Species Richness and Rarity-Weighted Richness analysis based on range polygons has been performed for:

All Red List Categories
Threatened species - species assessed as:
- CR (Critically Endangered),
- EN (Endangered) and
- VU (Vulnerable).

Each analysis was exported to a raster in the Mollweide projection, a projection that preserves equal areas across the globe. The raster cell size is 900 km² (30 km square). For the png images, the raster was reprojected to WGS84 and symbolised (in ArcMap) using the Standard Deviations (2.5) stretch.

Area of Habitat (AoH) rasters

Area of Habitat refines the raw polygon species ranges using habitat and elevation data. The process of creating AoH rasters from IUCN species polygon ranges is still under development and currently has only been applied to the 2021-3 Red List data for birds and mammals.

Downloads

Each analysis is available as:

raster geotiff (.tif)
- Species Richness from range polygons (file size less than 0.5 MB)
- Rarity-Weighted Richness from range polygons (file size less than 2 MB)
- Species Richness from AoH rasters (file size 3 MB - 6 MB)
- Rarity-Weighted Richness from AoH rasters (file size 30MB - 45 MB)
high resolution (2,000 dpi) image (.png)
- png from range polygons 2021 (file size 3 MB - 11MB)
- zipped png from range polygons 2022 (file size 2 MB - 6 MB)
- zipped png from AoH rasters (file size 3 MB - 6 MB)
lower resolution image (.pdf) - latest version only
- clicking on the thumbnail image will download a lower resolution pdf image (file size less than 1.5 MB)

Red List version 2024-2 Species Richness

Group(s)	All Red List Categories	Threatened Species
Amphibians, Birds, Mammals and Reptiles	Species Richness raster (zipped geotiff file); high resolution image (zipped png)	Species Richness raster (zipped geotiff file); high resolution image (zipped png)
Amphibians	Species Richness raster (zipped geotiff file); high resolution image (zipped png)	Species Richness raster (zipped geotiff file); high resolution image (zipped png)
Birds	Species Richness raster (zipped geotiff file); high resolution image (zipped png)	Species Richness raster (zipped geotiff file); high resolution image (zipped png)
Mammals	Species Richness raster (zipped geotiff file); high resolution image (zipped png)	Species Richness raster (zipped geotiff file); high resolution image (zipped png)
Reptiles	Species Richness raster (zipped geotiff file); high resolution image (zipped png)	Species Richness raster (zipped geotiff file); high resolution image (zipped png)

Group(s)

All Red List Categories

Threatened Species

Amphibians, Birds, Mammals and Reptiles

Species Richness raster (zipped geotiff file);

Species Richness and Rarity-Weighted Richness rasters

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