For the past two years, the majority-female Black Mamba Anti-Poaching Unit has patrolled the Balule Nature Reserve, a private wildlife reserve in northern South Africa. The Balule has an open border with Kruger National Park, an Israel-size reserve that has in recent years been besieged by poachers in pursuit of the park’s famed wildlife — particularly its rhinoceroses, whose horns are now worth hundreds of thousands of dollars on the international black market.

The German photographer Julia Gunther learned about the Black Mambas earlier this year. Gunther was working on a long-term photography project, “Proud Women of Africa,” which had so far documented nurses in Rwanda and a church-marching-band member, lesbian activists and transgender women in the townships and suburbs outside Cape Town. In the Black Mambas, Gunther said via email, “I knew I had found my next installment.” The Black Mambas “are taking on a typically male role and want to prove that women can also be rangers and scouts — that they, too, can positively influence the next generation.”