Methods

Original data in the form of ESRI shapefiles of species distributions were downloaded from the NatureServe Web site 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. For more information on these data sources, please visit the Acknowledgements page.

Data Transformations

To maximize compatibility for a wide range of applications, we converted the original shapefiles into ASCII grids, and then to the image-based .BIL format. There are two versions of .BIL files for each species, one using the maximum spatial extent of the original shapefile and maintaining all the information on the status of a occurrence (termed an “original grid"), and a presence/absence grid (termed a '“presence grid", in which 1=present and 0=absent) spanning the entire globe to facilitate raster calculations. The original grids retained the following coding for all classes (amphibians, birds, mammals):

Extant
Possibly present
Probably extinct/Historically present but no recent records
Extinct
Extirpated purposely (applies to introduced species only)
Occurs on indicated island chain, but not necessarily on every island in the chain
Subfossil/fossil

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.

Nomenclature

When mismatches in genus and or species names occurred between the NatureServe data and the WildFinder database, we settled on the taxonomic information provided by the sources listed below. For ease of use, our database retains the taxonomic information for species, genus, and family membership from both sources.

Taxonomic References

Amphibians: American Museum of Natural History Amphibian Species of the World 5.1, An Online Reference: :http://research.amnh.org/herpetology/amphibia/index.php.

Birds: The Sibley/Monroe World List of Bird Names: http://www.ornitaxa.com/SM/SMOrg/sm.html.

Mammals: Wilson, D. E., and D. M. Reeder (eds). 2005. Mammal Species of the World. Baltimore: Johns Hopkins University Press. An online database currently featuring the 1993 edition can be found at http://nmnhgoph.si.edu/msw/.

Notes on Synonyms

Notes about common synonyms or alternative spellings can be found in the "Notes" field of the data sheet that accompanies each download. Please keep in mind that we do not provide a comprehensive list of all possible synonyms. We suggest the following sources for information about synonyms or correct nomenclature:

Animal Diversity Web: http://animaldiversity.ummz.umich.edu/site/index.html

Global Biodiversity Information Facility: http://www.gbif.org/

IUCN Red List of Threatened Species: http://www.iucnredlist.org/

Mammalian Species: http:// www.science.smith.edu/departments/Biology/VHAYSSEN/msi/default.html

NatureServe: http://www.natureserve.org/

WildFinder: http://www.worldwildlife.org/wildfinder/

Data Limitations

The amphibian distribution data were developed by the Global Amphibian Assessment (GAA). 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. Almost 600 scientists from 60 countries have now contributed to the project. The objectives 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.globalamphibians.org/data.htm.

For the birds and mammal distribution maps, many of the source data were from earlier paper atlases of species distributions. For the birds, according to the metadata provided by NatureServe, most maps were digitized by eye or from scanned images of source maps occurring in field guides or species accounts (such as the Birds of North America series). These maps were then reviewed and appropriate corrections made to the database. A list of the references cited in the database for all species on Version 1.0 follows. Additional References cited on version 2.1 are available on the page of the associated species at www.natureserve.org/infonatura. Further information on the data are contained in the bird species metadata developed by NatureServe.

For the mammals, according to metadata provided by NatureServe, most maps were digitized either by scanning source documents, georeferencing the resulting image, and digitizing over range boundaries on the screen; or by eye from the source maps occurring in field guides or species accounts (such as the Mammalian Species Account series). These maps were then reviewed and appropriate corrections made to the database. A list of the references cited in the database appears in the References Cited document on this CD. When more than one reference was used for a particular polygon or point, the references for the northern portions of the range precede references for the southern portion of the range. Further information on the data are contained in the mammal species metadata developed by NatureServe.

Spatial Resolution and File Format

Users can search and download species distribution maps in ESRI shapefile and .BIL image formats for birds (aves), mammals (mammalian), and amphibians (amphibian). Bird and mammal data are available for the Americas only. Amphibian data are global in extent.

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.

Species Distribution Shapefiles

Original Vector files from NatureServe and its partners. Distributed without further processing.

Original Grids

Gridded versions of the shapefiles at 30 arc-second (1 km) resolution, in .BIL format. The grid cell values of these files represent Natureserve's seven categories of species presence.

Presence Grids

Boolean 1-0 grid files at 30 arc-second (1 km) resolution. "1" means that the species is known to be present (Natureserve Category 1) and "0" means that the species is absent (NatureServe categories 2–7). Amphibian grids are global and birds and mammal grids are for the Americas only.

Family Richness Grids

Grids representing an aggregation of the Presence Grids at the family level. For the Family Richness Grids (click on advanced tab to the left), each 30 arc-second grid cell represents a count of the number of species in that particular family. Richness grids are also available for each of the three classes: birds, mammals, and amphibians.

References

The species distribution grids are made possible because of the data freely distributed by the following sources. We appreciate the contributions of NatureServe and the Global Amphibians Assessment to the dissemination of biodiversity data, and in particular NatureServe’s Bruce Young and Conservation International’s Simon Stuart. We also acknowledge the World Wildlife Fund-USA for providing the WildFinder database, which formed the basis for the catalog of species grids.

Amphibians

Geospatial data in the form of ESRI shapefiles were provided by NatureServe. The data were developed as part of the Global Amphibian Assessment and provided by the IUCN-World Conservation Union, Conservation International, and NatureServe.

Citation: IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. IUCN, Conservation International, and NatureServe, Washington, DC and Arlington, Virginia, USA.

Web site: http://www.natureserve.org/getData/amphibianMaps.jsp

Birds

Geospatial data in the form of ESRI shapefiles were provided by NatureServe in collaboration with Robert Ridgely and James Zook, The Nature Conservancy-Migratory Bird Program, Conservation International-Center for Applied Biodiversity Science, World Wildlife Fund-US, and Environment Canada-WILDSPACE.

Citation: Ridgely, R. S., T. F. Allnutt, T. Brooks, D. K. McNicol, D. W. Mehlman, B. E. Young, and J. R. Zook. 2005. Digital Distribution Maps of the Birds of the Western Hemisphere, version 2.1. NatureServe, Arlington, Virginia, USA.

Web site: http://www.natureserve.org/getData/birdMaps.jsp

Mammals

Geospatial data in the form of ESRI shapefiles were provided by NatureServe in collaboration with Bruce Patterson, Wes Sechrest, Marcelo Tognelli, Gerardo Ceballos, The Nature Conservancy-Migratory Bird Program, Conservation International-CABS, World Wildlife Fund-US, and Environment Canada-WILDSPACE.

Citation: Patterson, B. D., G. Ceballos, W. Sechrest, M. F. Tognelli, T. Brooks, L. Luna, P. Ortega, I. Salazar, and B. E. Young. 2005. Digital Distribution Maps of the Mammals of the Western Hemisphere, version 2.0. NatureServe, Arlington, Virginia, USA.

Web site: http://www.natureserve.org/getData/mammalMaps.jsp

Wildfinder Database

A database of species and Redlist ("threat") status was downloaded from the WildFinder service of the World Wildlife Fund-USA.

Citation: World Wildlife Fund. 2007. WildFinder: Online database of species distributions, ver. July-07.

Web site: http://www.worldwildlife.org/wildfinder/learnMore.cfm