sentences:  Pregnancy of the female rhinos was monitored weekly.Rhinoceros gestation period takes 16 to 18 months, so in January 2014 the Conservancy considered Najin not pregnant, and a male southern white rhino from Lewa Wildlife Conservancy was put to Najin and Fatu enclosure in Ol Pejeta to at least intercross the subspecies.To achieve this, both female northern white rhinos were separated from their male counterparts, which prevented them from producing a pure northern white rhino offspring.