Geographical analysis of the Javan deer distribution in Indonesia and priorities for landscape conservation.
Javan deer (Rusa timorensis) is a protected species in Indonesia and considered to be vulnerable under IUCN list. Nevertheless, its native geographic distribution remains unclear, and the impact of abiotic and biotic factors on this species are mostly unknown. We predicted the potential range of Javan deer in Java and Bali Islands using ten environmental variables, occurrence data of native (76 before 1965, and 653 after 1965) and introduced populations (559), and MaxEnt modelling. We evaluated the effects of habitat loss due to current land use, ecosystem availability, and importance of Indonesian protected areas into the models. Our predictive map significantly improved the IUCN assessment and described for the first time the spread of Javan deer out of its native range within Indonesia. The model of environmental suitability estimated a potential of 3,784.43 km2 natural occurrence in Java and Bali and 36,352.61 km2 for introduced populations in protected areas of West Nusa Tenggara to Papua. The most critical environmental predictors for both populations are the mean annual precipitation and the conservation status of land. Then, 45.66% of the distribution of native populations overlaps with protected areas, 18.96% with production forests, 11.07% with non-protected areas, 10.10% with limited production forests and 4.20% with industrial oil palm plantations. Only 22.88% of the distribution of introduced populations overlaps with protected areas. Our study provides reliable information on places where conservation efforts must be prioritized, both inside and outside the protected area network, to safeguard one of the remaining Indonesian large deer.