Oh what a difference a century makes. At the beginning of the 20th century, an estimated one million black rhinoceroses from four different subspecies roamed the savannas of Africa. By 2001 that number had dropped to about 2,300 black rhinos and just three subspecies. This is the tale of how we lost one of those subspecies, the western black rhinoceros (Diceros bicornis longipes). It is a story of greed, indifference, hope and despair.

Historically, the western black rhino had a fairly large range across central and western Africa, with populations in modern-day Cameroon, Chad, the Central African Republic, Sudan and South Sudan, making it the northernmost African rhino subspecies. Although it had lived in these countries for centuries, the western black—like most rhinos—found itself to be incompatible with the 20th century. Widespread sports hunting in the first decades of the century quickly decimated rhino populations. Industrial agriculture came next, clearing many historic rhino habitats for fields and settlements. Farmers and ranchers at the time viewed large herbivores such as rhinos as pests and dangers to their crops. The slaughter continued.

The final nail in the rhinos' coffin began in the early 1950s, when Mao Zedong promoted so-called traditional Chinese medicine (TCM) as a tool for unifying the country he had recently come to lead. Even though Chairman Mao himself did not believe in TCM, he called for its use over Western medicine. Among the many "cures" touted by China's "New Medicine" was powdered rhino horn, which was said to cure everything from fevers to cancer. (This last claim is a fairly recent development.)

That's when poachers descended on Africa. Between 1960 and 1995 an astonishing 98 percent of black rhinos were killed by poachers, either to feed the new and voracious demand for TCM or, to a lesser extent, for horns to be used as ceremonial knife handles in the Middle East. All rhinos suffered; the western black rhino, already weakened by decades of overhunting, was the hardest hit.

By 1980 the western black rhino's range had shrunk to just two countries: Cameroon, which held 110 of the animals, and Chad, where just 25 remained. Chad's western blacks were wiped out within 10 years. Cameroon's held on a bit longer. The country held an estimated 50 western black rhinos in 1991, a number that dropped to 35 just a year later. By 1997 the population had fallen to an estimated 10 final rhinos.

Even that count doesn't fully convey the precarious nature of the subspecies at that point. The 10 last western black rhinos were scattered across 25,000 square kilometers of northern Cameroon. Four of them lived in fairly close proximity to one another. The remaining six lived in isolation, with an average of 60 kilometers between each animal and little, if any, hope to find one another and start breeding.

In 1999 the World Wide Fund for Nature (WWF) published a report called "African Rhino: Status Survey and Conservation Action Plan." The authors wrote of the almost insurmountable challenge in preserving these final 10 western black rhinos. "Demographically and genetically the western black rhino seems doomed unless the discrete populations are captured and concentrated in one area of its range. Under current conditions, however, this would probably make the remaining animals more vulnerable to poaching." The act of locating, catching and collecting these rhinos in one place would also be expensive and logistically next to impossible, as Cameroon at the time was plagued by corruption, civil unrest, currency devaluation and mistrust of the West. Even if that feat had been accomplished, the land in northern Cameroon was poorly suited for rhinos and provided very little food. Providing safe habitat for just 20 rhinos would require a fenced-in sanctuary 400 square kilometers in size. The authors wrote that the "lack of local conservation capacity and government commitment" would make consolidating the last rhinos difficult and concluded that the future of the subspecies was bleak.

They were right. Another WWF survey in 2001 found just five surviving western black rhinos, with the possibility of three additional, unconfirmed animals. That was the last time scientists or conservationists ever saw a western black rhino.

Even though things were grim at that point, a brief blip of hope occurred in 2004. That year, the nongovernmental organization Symbiose found evidence that as many as 31 western black rhinos still lived in Cameroon. That evidence, though, was quickly discredited. It turned out that trackers had faked rhino footprints in order to save their jobs.

Symbiose returned to Cameroon in 2006, conducing 46 field surveys over the course of six months. WWF and the Cameroon Ministry of Forestry and Wildlife also conducted a survey at the same time. The work wasn't easy. Roads were poorly maintained or nonexistent. Access to vehicles was expensive and unreliable. Armed gangs attacked travelers on many roads. Wherever the researchers traveled they saw evidence of illegal hunting for a wide range of species. Snares were present everywhere, waterholes had been poisoned and the teams frequently found wounded or trapped animals. Even though the area was classified as a national park, they found that poaching pressure in the region was 2.22 times higher than in official trophy-hunting zones.

Tragically, although the research team heard several anecdotes about lone rhinos living in the area, none of the surveys found any evidence that the western black rhino actually still existed. A paper published in Pachyderm that year concluded that the last members of the subspecies had been poached in or around 2003 and that the western black rhino was probably extinct.

People kept looking, but no rhinos were ever found. In 2011, with no sightings in a decade, the International Union for Conservation of Nature formally declared that the western black rhino had gone extinct.

Unfortunately, the western black rhino will not be the last rhino species or subspecies that we lose. The Javan rhino subspecies in Vietnam was also declared extinct in 2011. The northern white rhino is down to its last seven, non-breeding, aged adults. The main Javan rhino species is down to fewer than 50 individuals and the Sumatran rhino has fewer than 200. The remaining three black rhino subspecies as a whole are considered critically endangered (one subspecies is listed as "vulnerable to extinction," although its population is still quite low). The Indian one-horned rhino and the southern white rhino both enjoy healthier populations, but with poaching levels seemingly increasing almost every day, even they may not last long.

Will we learn from the lessons of the western black rhino's extinction? I think it's possible. Although the species disappeared a decade ago, many people are still just learning that it is gone. In the past week alone dozens, if not hundreds, of media outlets have run articles proclaiming that the western black rhino has gone extinct. Almost all of them mistakenly reported that the extinction happened just this past week—a burst of coverage set off by CNN republishing its two-year-old story with an "updated" date of November 6, 2013. This unleashed a veritable tsunami of sadness for the western black rhino on social media. In some ways it's good to see so many people express horror that the western black rhino has gone extinct. Maybe, just maybe, that will also lead to people caring about the rhino species that remain, and to take action before they, too, are gone.

Photos: A western black rhino photographed by M. Brunel in 1977 in Bouba Ndjida National Park, Cameroon, from Pachyderm: The Journal of the African Elephant, African Rhino and Asian Rhino Specialist Groups. Used under Creative Commons license. A western black rhino skull from an animal shot by a sportsman in 1911. Public domain, via Wikimedia Commons