These are draft sample maps (See preliminary maps below. These draft range maps will be updated over the next few months.) for Stephens' Kangaroo Rat based on a subset of available data. They are presented only to illustrate mapping approaches and not as definitive range maps. Actual range maps will be created using all available data and expert review.
Draft Range map based on known occurrences, modeled habitat distribution, and expert knowledge about geographic barriers and other factors affecting distribution. Range maps will be subject to expert review and field testing.
Map generated by ArcInfo's grid module from a model that locates the intersection of all environmental variables considered capable of supporting a species. This model exclusively uses Boolean “AND” statements.
Map generated by ArcInfo's grid module from a model that uses expert opinion and published information on habitat conditions that influence the distribution and abundance of Stephens' Kangaroo Rat. Complex logical rules with nested Boolean logic, patch dynamics, weighted variables, and rankings of habitat suitability are possible.
Species-likelihood map generated using Ecological Niche Factor Analysis (ENFA) implemented in the program Biomapper. ENFA is a multivariate statistical method that uses only data on the species' presence. (Hirzel A.H., Hausser J., Chessel D. & Perrin N. 2002. Ecological-niche factor analysis: How to compute habitat-suitability maps without absence data? Ecology 83:2027-2036). Biomapper can be downloaded at http://www.unil.ch/biomapper.
