New study finds that fragmented habitat increases extinction risk in mammals

In a first-of-its-kind study, CSP’s Dave Theobald and others develop a series of high-resolution models to assess how habitat fragmentation impacts extinction risk for mammals on a global scale.

CSP was part of an international team of researchers that examined habitat fragmentation for over 4,000 species of land-dwelling mammals across the globe. The team used high-resolution models and comparative analyses to measure fragmentation and to assess its relationship to extinction risk. In addition to documenting the conservation status of animals and plants, the team produced global maps that predicted areas of intact, high-quality habitat — as well as fragmentation hot spots. They found that mammals within highly fragmented areas enjoyed smaller ranges and a lower proportion of high-suitability habitat. They also determined that most high-suitability habitat occurred outside of protected areas, further elevating extinction risk.

Fragmentation — a result of urban development, roads, and deforestation —not only reduces the total amount of available habitat but it also isolates habitat, preventing the movement of animals in previously connected landscapes. This isolation in turn limits the ability of wildlife to shift locations in response to climate change.

The study was conducted by scientists from Colorado State University, CSP, The University of Queensland (Australia), and Sapienza University (Italy). The results will help guide threat assessment and conservation priorities.

To learn more, download the paper, which was published in the Proceedings of the National Academy of Sciences, here.

Species richness and degree of habitat fragmentation (corrected for species richness) for the world’s terrestrial mammals. (A) Species richness based on extent of suitable habitat. Blue denotes sites with few mammal species, and red denotes sites with the highest species richness. (B) Degree of habitat fragmentation, corrected for species richness by dividing the fragmentation metric within each cell globally by the number of species with suitable habitat within that cell, thus generating an average fragmentation index (Methods). Blue denotes sites with low fragmentation, where terrestrial mammals, averaged across species with suitable habitat at a site, have the most intact high-suitability core habitat. Red denotes sites with high fragmentation, where mammal species on average have little core habitat.