The Kalahari Gemsbok National Park together with the Gemsbok National Park in Botswana, makes up Africa's first transfrontier game park, known as the Kgalagadi Transfrontier Park.
As they report in the Journal of Mammalogy, they found that as the female lechwe got older, the sex and the birth weight of their young steadily shifted.
At the edge of a sprawling grassland, a pair of hoofed grazers resembling horses, an antelopelike notoungulate and a ground sloth feed quietly, oblivious to their impending doom.