Why do poachers commit crimes where and when they do? How can the vast areas of nature reserves most effectively be patrolled by ranger teams. Starting from an environmental criminology perspective, this PhD project investigates poaching problems in South Africa. It addresses questions regarding poacher behavior and ranger team effectiveness. The project analyzes ranger tracking data, geo-referenced poaching sites, and data from poaching detection experiments. It also uses agent-based modeling to understand how ranger team operations can most effectively be organized.