The development of sophisticated delivery equipment, as well as safer and more effective drugs, has made remote delivery of animal drugs a standard and readily available tool for wildlife professionals, veterinarians, ranchers, and animal control officers. In the 1980s, researchers began treating a wide variety of wildlife with injectable porcine zona pellucida immunocontraceptive vaccines. Remote delivery of immunocontraceptives has been proven effective at the individual and population level for wild horses and urban deer. However, it took only a short time at each study site to understand that each time an animal was treated with remotely delivered darts, it became more difficult to re-treat; researchers were required to adjust to the increased wariness of their targets. Multiyear vaccines will not reduce the need for researchers who can adapt to the many challenges of applying these nonlethal methods of population control in the field. Training, experience, and persistence are required for field personnel to adapt and develop new techniques for continued retreatment of previously treated free-ranging animals.