texas. they're the newest additions to the sprawling ox ranch in the texas hill country. >> we're just trying to keep the genetic diversity within the different species. >> reporter: jason manages the herds of roughly 60 species spread across 16,000 acres of land on the ox ranch. at every turn you come across not just native white tail deer but a dizzying array of africa species. hunters shell out big money for a guided excursion to hunt down prize trophies on this land, choosing from a menu of animals to hunt, paying anywhere from a few thousand dollars to as much as $35,000. they say they're doing it not just for the thrill for the hunt but in the name of conservation. >> i know it sounds contradictory but hunters love animals. >> reporter: hunters pay to hunt the oldest males that are past breeding age.