The Gridded Species Distribution data collection consists of richness rasters of amphibians and mammals. The data are available as richness rasters for the entire class, individual families, or IUCN Red List threat categories. Original data in the form of ESRI geodatabase featureclasses of species distributions were downloaded from the IUCN Red List of Threatened Species website (http://www.iucnredlist.org/) and gridded using the process described below. The searchable catalog of species is a modified version of the WildFinder database, version July 2007, which included additional taxonomic information and threat status.
To maximize compatibility for a wide range of applications, we converted the original shapefiles into geotiff raster format. Individual species distribution polygons are converted to Presence raster using the Extant class attribute. The Presence raster of all the species in each family are combined (using addition operator) to create the Family or Threatened category Richness raster.
We excluded all species from the database for which only isolated records (point files) existed. We also excluded all species that are considered extinct in the wild.
We relied on IUCN Red List nomenclature, species and family distributions in creating richness rasters. Detail description of assessment process and data on Mammals can be found at http://www.iucnredlist.org/initiatives/mammals/process and amphibians in http://www.iucnredlist.org/initiatives/amphibians/process.
The amphibian distribution data were developed by the Global Amphibian Assessment (GAA) in 2004. The GAA is the comprehensive status assessment of the world's 5,918 known amphibian species, against the IUCN Red List Categories and Criteria, and as such is an important contribution to the Red List Programme. The objectives of the assessment were to: (a) determine the scale (both the magnitude of threat and the geographic focus) of the current extinction crisis in amphibians; (b) identify the most important geographic areas and habitats that need to be conserved to avoid further species extinctions; (c) identify the major threats and to propose mitigating measures and prioritized conservation actions to address them; and (d) establish an expert network focused on amphibians so that the Global Amphibian Assessment can be kept current, and expertise can be targeted to address the highest conservation priorities. A full description of the data and their limitations can be found at http://www.iucnredlist.org/initiatives/amphibians/process/methods.
The mammal data on the 2008 IUCN Red List includes 5,488 species in 156 families. The primary focus of the current assessment was at the species level, and all species assessments are complete including all supporting documentation. Details of the assessment process can be found at http://www.iucnredlist.org/initiatives/mammals/process.
Spatial Resolution and File Format
Users can search and download richness grids in geotiff format for mammals (mammalian), and amphibians (amphibian). All data are in geographic coordinate system. The data sets are at a nominal map scale of 1:1,000,000. Grids are provided at 30 arc-second (~1 km) resolution.
Family Richness Grids
Grids representing an aggregation of the Presence Grids at the family level. Each 30 arc-second grid cell represents a count of the number of species in that particular family.
Threat Status Richness Grids
Richness rasters are available for the following IUCN threat categories, namely, Vulnerable, Endangered, Critically Endangered and All Threats.