The Kansas City Zoo got a special start to the new year: A critically endangered subspecies of rhinoceros gave birth to a calf on Dec. 31, officials announced.The calf is walking, nursing and even playing with its mother, Zuri, animal specialists said.Save the Rhino, a rhinoceros conservation charity, said that a female rhino will be pregnant for 15-17 months before finding a solitary place to give birth.Save the Rhino cites poaching and lack of a safe habitat as the worst threats against the species.The World Wildlife Foundation said that the rhino's horn makes them targets for poaching, and that political instability in Africa, its habitat, is driving those efforts."