Some claim a small but viable population of about a dozen rhinos persists deep within the forests of Bukit Barisan Selatan National Park on Sumatra’s southwestern coast.Camera traps haven’t captured a single rhino there since 2014, spurring doubts there are any rhinos remaining at all.The disputed numbers lead to questions about what should happen to any rhinos that might remain in the park — and to the rangers assigned to protect them. This is the second article in our four-part series “Is Anyone Going to Save the Sumatran Rhino?” Read Part One, a look at how many rhinos remain in the wild here. LAMPUNG, Indonesia — Dripping with sweat, breathing heavily, I followed several members of the Rhino Protection Unit (RPU) down a steep, forested slope characteristic of Sumatra’s Bukit Barisan Selatan National Park. I was thankful whenever we paused: to look at a spot where a deer had rubbed against a tree, or examine the cabbage-like giant Rafflesia flower that we’d just missed blooming. Near the bottom of the slope we stopped long enough to take a drink over a large indentation in the ground. “This is Rosa’s wallow,” said Marsum, the field coordinator of the RPUs at Bukit Barisan Selatan, on the southwestern coast of the island of Sumatra. “Rosa? Wait — the rhino Rosa?” “Yes, she used to wallow here,” explained Marsum, who, like many Indonesians, goes by one name. We were within 20 minutes’ walk of the road and the RPU camp, a cluster of buildings on the slopes of cloud forest. A Sumatran rhino (Dicerorhinus sumatrensis), here? Rosa at her home at the Sumatran Rhino Sanctuary. Photo by Willem v Strien via Flickr. Today, Rosa lives in the Sumatran Rhino Sanctuary (SRS), just inside Way Kambas National Park on Sumatra’s east coast, where she was moved in 2005 for her safety. Unlike most of her kind, Rosa had become unafraid of people, even eating out of their gardens. The last straw came when she was found in a local market, followed by hundreds of villagers. Zulfi Arsan, the head veterinarian at the SRS, describes her behavior as “kind of disturbed”. Around the time of Rosa’s escapades, experts estimated that Bukit Barisan Selatan was home to 60 to 80 rhinos. But Rosa may have been one of the final rhinos of Bukit Barisan Selatan, representing a last gasp for this population, and a warning of imminent extinction of her species — the oldest, smallest, hairiest and most vocal of the rhinos. There are two narratives about the rhinos in Bukit Barisan Selatan. One claims that a small but potentially viable and still breeding population of about a dozen individuals persists deep within the forest. The other is that the rhinos are all but gone; maybe a few individuals survive or maybe the last one died in recent years, leaving Bukit Barisan Selatan bereft of the Sumatran rhino, like so many other sites in Asia today. The story of Bukit Barisan Selatan’s rhinos, and whether Rosa was one of the last, raises the central question of Sumatran rhinos today: should we capture the rest of the rhinos for captive breeding, or can any population still survive in the wild? But there is another, lesser discussed, question here. What happens to the brave men and women who today protect the rhinos of Bukit Barisan Selatan? What happens to the Rhino Protection Units if there are no more rhinos to protect? Bukit Barisan Selatan National Park lies at the southwestern tip of Sumatra Island. Way Kambas, another rhino habitat is to the east, and Kerinci Seblat, once home to the species, to the north. Rhino signs? In an effort to better count Bukit Barisan Selatan’s rhinos, Rhino Protection Units collected 62 samples of rhino dung in 2012 and 2013. But when genetic testing was performed, the results surprised everyone: over 60 percent of the samples were not rhino, but tapir. As experts watched rhinos disappear from other sites like Kerinci Seblat National Park, further north along the Bukit Barisan mountain range, and Sabah in Malaysian Borneo, a discomfiting realization overtook them: we’d been overestimating Sumatran rhino populations for decades. Was the same thing happening in Bukit Barisan Selatan? Were we confusing signs of tapir, and other large animals, for rhinos? Were we victims of wishful thinking? The RPU, which is funded largely by the International Rhino Foundation (IRF), has four tasks: protection, surveying, habitat restoration, and investigation of poachers and the illegal wildlife trade. But after the tapir dung incident, many began to question whether the RPUs had the expertise necessary to accurately estimate rhino populations. Were they, as had happened so many times before, finding “rhinos” where there weren’t any? Currently the RPUs monitor rhinos via “signs”: footprints, dung, wallows, twisted branches. But there are problems with each of these signs. One can mistake a tapir footprint for that of a rhino, especially if the footprint is old or degraded. Dung, as shown by the genetic study, has also proven problematic. Wild pig wallows and rhino wallows look practically the same. And while rhinos are the only animals in the area that twist branches as they eat, it’s still possible to mistake a twisted branch for the existence of a rhino. A rhino wallows in the mud at the Sumatran Rhino Sanctuary — a behavior also shared by other local species. Photo by Rhett A. Butler/Mongabay. None of this is to say that the RPUs aren’t doing their jobs well; few people have more day-to-day, on-the-ground expertise with rhinos than RPU staff. Some of them have been protecting rhinos since the late 1990s, putting their lives on the line for a species they almost never see in the flesh. “It’s easy to distinguish rhino and tapir [footprints] and I believe our team … know how to distinguish [them],” said Inov Sectionov, the Indonesia program coordinator for the IRF. Still, humans make mistakes. And errors may become more common when monitoring a species that is barely there anymore. For example, what happened with the rhino dung that turned out to be tapir? Arief Rubianto, the manager of the RPUs in Sumatra, said rain during the collection period made it more difficult to tell the dung apart. “This is not the fault of the RPUs,” he said, noting that the team collected as much dung as they could in the hope of getting as many samples of rhino DNA as possible. Arief said RPUs are finding fewer rhino “signs” in Bukit Barisan, but he contends this doesn’t mean the rhino population has decreased, because RPUs have not found any signs of dead rhinos in recent years. Instead, he argues, encroachment, fires and other human activities have driven rhinos deeper into the park’s steep slopes — hardly prime habitat for a species that many believe probably preferred lowland forests and grasslands before humans wiped them out from those areas. He added the government has “not successfully handled” illegal activities in the parks. Arief claims there are at least 12 rhinos left in Bukit Barisan Selatan, including two calves this year, based on footprints. The population, he says, is “stable” but “very low.” If true, it may be enough to make up a viable population, assuming they are all capable of breeding (a 2015 report estimated a minimum of 15 rhinos would be needed for a viable population). But Arief’s estimate was the most optimistic I heard.