Applying the niche reduction hypothesis to modelling distributions: A case study of a critically endangered rodent

The 'niche reduction hypothesis' (NRH) is based on the idea that the realized niche of a declining species is reduced by threats that are mediated by environmental, biotic and evolutionary processes. The hypothesis was promoted to identify locations and interventions most likely to benefit declining species. We used a niche reduction approach to species distribution modelling by predicting the historic and current distributions of a critically endangered Australian rodent, the central rock-rat (CRR). Our habitat suitability maps confirm a dramatic range contraction for this species over the last 100 years. The current association of CRRs with extreme landscape ruggedness supports the hypothesis that the impact of a key threat to the species-cat predation-is mediated by habitat complexity. We detected no CRRs in five new locations predicted to be highly suitable in the current distribution model. This highlights the need for in-situ threat management at the three known sub-populations, one of which may already have been extirpated. Our map of the CRR's historic distribution identifies potential areas for translocation, including the site of a current translocation proposal into a predator-proof fence. We conclude that the NRH provides a useful framework for modelling the change in distributions of declining species in order to prioritise locations and interventions for management.