Restoring Large Mammal Assemblages: New Study Reveals Opportunities to Recover the Faunal Integrity of Ecosystems Worldwide

A new RESOLVE-led study reveals major opportunities to restore ecosystem integrity across vast areas of the globe by reintroducing historically present large mammals. The paper, titled "An ecoregion-based approach to restoring the world's intact large mammal assemblages," has been published this month in the journal Ecography as part of a Special Issue on Restoration. The paper shows that by restoring only 20 large mammal species—including brown bear, bison, lion, jaguar, and wild horse—more than 8.5 million square kilometers can once again regain intact large mammal communities with all of their historically present large mammals.

The research team includes RESOLVE (Dr. Carly Vynne, Dr. Eric Dinerstein, Andy Lee, and Sanjiv Fernando), UN Environment Programme – World Conservation Monitoring Centre, and a group of leading wildlife biologists from 10 countries. Financial support for the study was provided by One Earth.

Large mammals play important roles in the shaping and maintenance of natural processes in many terrestrial ecosystems. They also contribute to carbon storage and are key to climate stabilization. However, the transformation of natural habitats by humans has reduced the range of many large mammal species. Places where intact large mammal faunas remain or where they could be feasibly restored are a conservation priority. This paper identifies both remaining and restorable areas.

Using datasets from IUCN and recently published literature, the research team compared the current distribution ranges of 298 extant large mammal species with their historical natural ranges to identify the presence and absence of intact mammal assemblages. The resulting data layers represented the world's first global "heat map" of large mammal distribution change over the last five centuries.

The analysis revealed that only 15% of the world's land area currently support intact groupings of large mammals. Ecosystems in the Amazon, East Africa, and the western United States represent some of the last remaining strongholds for large mammal faunas. On the other hand, large tracts of habitat in India, eastern Europe, the central United States, Brazil, and southern Africa suffered significant decreases in large mammal representation both by population size and range.

Figure 1. Global map showing present-day areas with no (dark green), 1–3 (light green), or > 3 (red) large mammals missing from their natural distribution in 1500 AD.

Mammal reintroduction efforts have been successfully implemented for a range of species in many diverse biomes. This study used a holistic approach to assess how much of the world could be feasibly restored with all the historically-present large mammal species. The paper also highlighted 30 priority ecoregions, selected by expert wildlife conservationists, where restoration efforts in the near future are highly feasible for the recovery of intact large mammal assemblages spanning across 61 countries.

The paper's dataset, tabulated by individual species and spatially by biogeographical realms and ecoregions, provides countries or regions with a starting place for identifying restorable landscapes and target species to consider.

As we celebrate the United Nations Decade on Ecosystem Restoration (2021–2030), this study provides a template for how wildlife recovery can support global biodiversity objectives and be a central pillar of area-based conservation objectives such as achieving the protection of 30% of Earth's terrestrial and marine areas by 2030.

Since its publication, the study has received coverage from multiple outlets in the science and conservation communities, including Mongabay, Bloomberg,, UNEP-WCMC, IFLScience, and the Guardian.

For more information or questions about the study, please reach out to

Link(1) The paper in Ecography:

CitationVynne, C., Gosling, J., Maney, C., Dinerstein, E., Lee, A. T., Burgess, N. D., ... & Svenning, J. C. (2022). An ecoregion‐based approach to restoring the world's intact large mammal assemblages. Ecography.

Cover image credit Abhijit Patil via Flickr (CC BY-NC-ND 2.0)

Video created by One Earth

Andy Lee, Carly Vynne, Eric Dinerstein, and Sanjiv Fernando


April 21, 2022