Keeper Zachariah Mutai attends in March to Fatu, one of only two female northern white rhinos left in the world, in the pen where she is kept for observation, at the Ol Pejeta Conservancy in Laikipia county in Kenya. Scientists have successfully grown hybrid white rhino embryos in the lab, stoking hopes that a purebred northern white rhino could be implanted in a surrogate. Sunday Alamba/AP hide caption
Sudan, the world's last male northern white rhino, grazes at the Ol Pejeta Conservancy in Kenya in May 2017. The 45-year-old rhino's health started deteriorating in late February. STR/AP hide caption
The Philippine eagle Pithecophaga jefferyi faces extinction from mining, pollution and poaching. Photographer Tim Flach used black backgrounds to create intimate portraits for his book. Tim Flach hide caption
Sudan, the last known male of the northern white rhinoceros subspecies, stands for his close-up in a paddock last year at the Ol Pejeta Conservancy in Kenya. If Tinder users swipe right on Sudan's profile, they're taken to a page asking for contributions to help him reproduce. Tony Karumba/AFP/Getty Images hide caption
Najin, a female northern white rhino, gets a pat from keeper Mohamed Doyo. Najin, who lives at the Ol Pejeta Conservancy in Kenya, is one of only five of its subspecies left in the world. Ben Curtis/AP hide caption