Global habitat suitability models of terrestrial mammals

Abstract

Detailed large-scale information on mammal distribution has often been lacking, hindering conservation efforts. We used the information from the 2009 IUCN Red List of Threatened Species as a baseline for developing habitat suitability models for 5027 out of 5330 known terrestrial mammal species, based on their habitat relationships. We focused on the following environmental variables: land cover, elevation and hydrological features. Models were developed at 300 m resolution and limited to within species' known geographical ranges. A subset of the models was validated using points of known species occurrence. We conducted a global, fine-scale analysis of patterns of species richness. The richness of mammal species estimated by the overlap of their suitable habitat is on average one-third less than that estimated by the overlap of their geographical ranges. The highest absolute difference is found in tropical and subtropical regions in South America, Africa and Southeast Asia that are not covered by dense forest. The proportion of suitable habitat within mammal geographical ranges correlates with the IUCN Red List category to which they have been assigned, decreasing monotonically from Least Concern to Endangered. These results demonstrate the importance of fine-resolution distribution data for the development of global conservation strategies for mammals.

Figure 1.

Validation of habitat suitability models for the 263 mammals with occurrence data. Each circle represents a species, and the size of the circle is proportional to the square root of the number of available occurrences for the species. Model prevalence: proportion of 1 km² cells containing habitat with medium or high suitability within the species' range. Point prevalence: proportion of points correctly predicted (i.e. falling in cells containing habitat with medium and/or high suitability for the species).

Figure 2.

Mammal richness based on (a) geographical ranges and (b) habitat suitability models (high and medium suitability combined). Black lines on maps indicate biogeographic realms. The two upper limits on the scale bar indicate maximum richness based on habitat suitability models (191) and geographical ranges (212), respectively.

Figure 3.

(a) Absolute and (b) relative difference of mammal richness estimated by geographical ranges and habitat suitability models. Absolute difference is represented as number of species. Relative difference is equal to absolute difference divided by the species richness estimated by geographical ranges. Black lines on maps indicate biogeographic realms.

Figure 4.

Tukey boxplots of the proportion of suitable habitat in mammal geographical ranges by (a) biogeographic realms (Pal., Palaearctic; Afr., Afrotropical; Ind., Indomalayan; Aus., Australasian; Oce., Oceanian; Nea., Nearctic; Neo., Neotropical; >1: species distributed in more than one realm), (b) preferred habitat type and (c) IUCN Red List category, indicating increasing risk of extinction from low to extremely high (LC, Least Concern; NT, Near Threatened; VU, Vulnerable; EN, Endangered; CR, Critically Endangered). The dotted line represents the log size of species geographical ranges.