Central Africa has become increasingly inhospitable to forest elephants, according to a study published March 4 in PLoS One that found that 62 percent of the species was killed by poachers between 2002 and 2011. The study—by scientists from the Wildlife Conservation Society (WCS) and more than a dozen other institutions—also found that 30 percent of the elephants' prior habitat has become inhospitable during that timeframe.

Forest elephants (Loxodonta cyclotis) live exclusively in central Africa, while savannah, or bush, elephants (L. africana) can be found in the southern, eastern and western stretches of the of the continent. Scientists had thought that forest and savannah elephants were the same species, but a genetic study published in 2010 proved that they are two separate species. Forest elephants are roughly 15 percent smaller than their savannah cousins and have harder, straighter tusks.

The new study—which will help conservationists understand the unique needs of the newly recognized species—required a massive effort. More than 60 scientists spent a combined 91,600 person-days in the field. They walked more than 13,000 kilometers through Cameroon, the Central African Republic, the Democratic Republic of the Congo (DRC), Gabon and the Republic of the Congo and collected more than 11,000 samples—primarily dung—over a 10-year period. The density of dung samples dropped dramatically in that period, which is how the scientists calculated the 62 percent population decline.

The study also revealed major changes in where forest elephants can be found. Before the 1970s, nearly 60 percent of all forest elephants lived in the DRC, while 18 percent lived in Gabon. As of 2011, according to the study, the DRC's population had been poached so heavily that it only contained 19 percent while 52 percent of all remaining forest elephants lived in Gabon.

Other surveys released separately help illustrate just how many elephants we're talking about. In early February the WCS revealed that Gabon's Minkebe Park has lost 11,100 elephants since 2004, most of which were probably killed in the past five years, a big change for a country were poaching was at the lowest levels in the region. Another survey released later that month found that the supposedly well-protected Okapi Faunal Reserve in the DRC has lost 5,100 elephants in the past 15 years. Many of them were killed during the worst years of that country's 1996-2003 civil war.

Although most raw, unworked ivory, regardless of species, is destined for China, a previous WCS study, published in the July-December 2012 issue of the journal Pachyderm (pdf), found that Japan is the only market with a preference for the harder forest-elephant ivory. Softer savannah-elephant ivory is not considered durable enough for traditional hanko (personal name seals) or bachi (carved plucking tools for three-stringed musical instruments called shamisen).

Previously in Extinction Countdown: