sentences:  It was assumed that the three rhinos that were spotted belonged to the northern white rhinoceros subspecies, as black rhinos had not lived in the area for a long time and southern white rhinos never lived in southern Sudan.However, as of August 2011, no other sightings have been reported, and this population is now considered to have probably gone extinct.At the beginning of 2015, the fully captive northern white rhino population consisted of only two animals maintained in two zoological institutions