Administering contraception via dart might sound a bit unusual compared with the average human approach, but for wildlife managers, it provides a way to keep populations in check without resorting to culling or other lethal methods. From a distance, rangers can deliver a prophylactic payload - an immunocontraceptive vaccine, rather than hormones - without anesthesia.
As 2011 report in the American Journal of Reproductive Immunology notes, steroid hormones can have adverse effects as they travel throughout the ecological web. Vaccines can target a specific species, on the other hand, triggering an immune response that prevents egg fertilization. And should elephant numbers dip, the effects can be reversed.
"We're delighted to see more and more elephant managers count on this technology to control elephant population growth in a proactive, effective and humane manner," said Audrey Delsink, director of Humane Society International's Elephant Contraception Program, in a statement, "and hope it becomes universally adopted."