There are two groups of people shooting rhinos in southern Africa today. The first are poachers, who shoot to kill, then hack off horns and gouge out eyes. The second are game wardens, who stun with tranquilizer darts, then insert tracker microchips into the horn. After a lull for more than a decade in which rhino numbers began to recover, in the past few years the poachers have gained ground once more: 333 rhinos died in southern Africa last year, and the kill rate has accelerated again this year.

Why are rhinos dying again? Because globalization has lots to say about making billions of people richer, but nothing to say about what to do with the money. Rhino horn has been used in traditional medicine in China and Vietnam for centuries. Now that a new Asian elite can pay the earth for it, a new international poaching mafia is scouring the planet to satisfy that demand. The money on offer has persuaded more than a few game hands to turn poacher. It has persuaded others that, since a rhino does not have to die to give up its horn, and since only a live rhino can grow another one, legalizing horn sales and farming rhinos may be the only answer. Since a live animal would then be more valuable than a dead one, the thinking goes, it might even prompt a population increase.

For now, heavily armed rangers and poachers play a deadly game of cat and mouse across the bushlands of South Africa and Zimbabwe, frequently killing each other as they race from dawn to dusk to find the next unguarded rhino. The rangers are flat out. So are the poachers.

-Alex Perry

Dominic Nahr, a TIME contract photographer, photographed the aftermath of the Japanese earthquake and tsunami and the spring uprising in Egypt. Nahr is represented by Magnum.