Ben Carter, executive director of the Dallas Safari Club, told the media that 100 percent of the auction proceeds will support the Conservation Trust Fund for Namibia's Black Rhino.

"There is a biological reason for this hunt, and it's based on a fundamental premise of modern wildlife management: Populations matter; individuals don't,” Carter said. “By removing counterproductive individuals from a herd, rhino populations can actually grow."

Scientists estimate that there are about 5,055 black rhinoceroses left in the world, a decline of about 96 percent over the past century or so. They were listed in Appendix I of CITES in 1977 and on the U.S. Endangered Species Act in 1980; they are are currently listed as critically endangered on the IUCN Red List of Threatened Species.

Even so, all three of those bodies—CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora), the U.S. Fish and Wildlife Service, and IUCN—are on record as allowing limited, targeted hunting.