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Hillshade generated from SRTM 90m DEM available from the CGIAR website (http://srtm.csi.cgiar.org/).
Bathymetry from the ETOPO1 Global Relief Model downloaded from: http://www.ngdc.noaa.gov/mgg/global/global.html
Sumatran orangutan distribution shapefile prepared by Singleton and Wich and based on Wich et al. 2008 with unpublished data added.
The Relative Population Density layer was prepared by PanEco/YEL from official population statistics of Aceh and North Sumatra (Central Bureau of Statistics) for 2008-2009 and the shapefiles for human habitations of the 1:50,000 Bakosurtanal Topographic maps for Indonesia, with additional points for populations (such as in the Alas valley) not shown in these maps. NB. Data for some areas of North Sumatra (but not adjacent to orangutan habitat) are not shown (e.g. Nias island).
Uploaded on Wednesday 01 Feb 2012
Human relative population density
Riccardo Pravettoni, UNEP/GRID-Arendal
Only areas with very low human population densities harbour orangutans. In Aceh and North Sumatra, human settlements are still primarily concentrated in the relatively flat coastal zones, particularly along the north and east coasts, and in alluvial areas elsewhere.