Indigenous range maps are fundamental documents in biogeography and conservation. We define the indigenous range of a species as ecoregions (or parts of ecoregions) where the species was likely found before human beings became a major factor shaping the species’ distribution, beginning at a time when the geographic alignment of the continents and the prevailing climate are (or at least were) roughly consistent with current conditions. We developed a structured, generally applicable, method to map a species' indigenous range and applied this process to the tiger (Panthera tigris). We synthesized a database of over 70,000 tiger observations with times and locations to guide our mapping. We developed a structured Delphi process to assign categories of indigenous range to ecoregions aided by a climate niche model. We analyzed tiger habitat change at the ecoregional scale using the anthropogenically-modified biomes (“Anthrome 12K”) dataset to suggest dates of first significant human impact. Finally, for ecoregions where tigers have been extirpated, we estimated extirpation dates. We found the tiger once occupied a likely indigenous resident range of approximately 11.5 million km2, crossing 116 ecoregions. We also mapped an additional approximately 11.7 million km2 of exploratory range and 1.2 million km2 of possible resident range. Collectively these areas overlap with 36 modern countries. Significant human disruption of the species habitat seems to have begun over 6000 years ago in some areas, but in others, remarkably, has yet to materialize in terms of significant habitat loss. In some ecoregions, human activities appear to have increased habitat availability in the past, yet overall tigers have lost between 90-95% of their indigenous range. We define "indigenous range" of a species, develop a replicable biogeographical procedure, apply the procedure to the tiger, and discuss the conservation implications.

We synthesized a database of over 70,000 tiger observations with times and locations to guide our mapping. We developed a structured Delphi process to assign categories of indigenous range to ecoregions aided by a climate niche model. We analyzed tiger habitat change at the ecoregional scale through a reclassification of the anthropogenically-modified biomes (“Anthrome 12K”) dataset to suggest dates of first significant human impact. Finally, for ecoregions where tigers have been extirpated, we estimated extirpation dates.