In 1986, scientists estimated there could be as many as 800 Sumatran rhinos left. That fell to 400 in 1996, then 275 in 2008.Today the official estimate is 100 rhinos, but almost all experts believe that figure is overly optimistic.Adding up the minimum estimate for each of the four known wild populations yields a total of just 30 wild Sumatran rhinos left on earth, plus another nine in captivity. This is the first article in our four-part series “Is Anyone Going to Save the Sumatran Rhino?” WEST JAVA, Indonesia — As we sit cross-legged at a restaurant in Java over plates of local delicacies — cow brains, avocado juice and dried fish you eat whole — Haerudin R. Sadjudin tells me a little about his life. Lanky, weathered, with a welcoming demeanor and an open smile, Haerudin, 62, started studying rhinos — both Indonesian species, the Sumatran and the Javan — in 1975. I tell him he’s been doing this job longer than I’ve been alive. Haerudin, program manager at local rhino NGO YABI, has had the pleasure of seeing Javan rhinos (Rhinoceros sondaicus) 31 times in the wild. He’s been attacked by them three times, including once when he had to abandon his canoe and cling to a tree. But this isn’t what really takes my breath away. He’s actually seen Sumatran rhinos (Dicerorhinus sumatrensis) in the wild — but only once in his 40-plus years of studying the animal. This highlights just how endangered the Sumatran rhino has long been. Already by the 1970s they were virtually impossible to encounter. And today they are so rare, so nearly lost, as to be almost mythical: they’ve become like the Tasmanian tiger in the 1920s or Steller’s sea cow in the 1760s. The world knows exactly how many Javan rhinos are left: 67, including four calves this year. We know this because of consistent surveys using camera traps, and because all the Javan rhinos survive in a single park, Ujung Kulon. Despite such a small population, the Javan rhino is still far better off than the Sumatran today. Its population is stable, even growing every year. By contrast, the Sumatran rhino is vanishing before our eyes, and we have no idea know how many have disappeared or how many are left to lose. In 1986, the same year the species was added to the IUCN Red List as Endangered, scientists believed there were 425 to 800 Sumatran rhinos left on Earth. In 1996, when the species was listed as Critically Endangered, that number dropped to 400. Then, in 2008, the estimate fell to 275. Just seven years later, the official figure became 100 individuals, nearly two-thirds lost just like that. As grim as that figure is, the reality is likely much bleaker.