Number of Mammal Species by Freshwater Ecoregion

Number of freshwater mammal species, by freshwater ecoregion.

Freshwater mammals include aquatic or semiaquatic species that spend a considerable amount of time in freshwater to feed and that usually live in the riparian vegetation close to rivers, lakes, marshes, swamps, and other freshwater habitats. We used species range maps, visual assessment of locations based on literature descriptions, and expert opinion to assign mammal species presence to ecoregions. Range species maps and distribution information for individual species were obtained from multiple sources and literature sources were used to determine whether a species is considered a freshwater mammal.

Rodents make up at least 50 percent of all mammal species, and this percentage is probably underestimated given that every year more than thirty to forty new rodent species are recognized. In general, rodents are a poorly studied group; therefore, the number of species considered “freshwater rodents” in this data set is underestimated, and the species numbers are likely to be much higher.

These data were derived by The Nature Conservancy, and were displayed in a map published in The Atlas of Global Conservation (Hoekstra et al., University of California Press, 2010). More information at http://nature.org/atlas.