There are only 250 adult lions left in West Africa, according to a six-year survey by the big cat conservation organization, Panthera. The survey into 11 African nations revealed that lions are present only in five West African nations: Senegal, Nigeria and on the shared borders of Benin, Niger and Burkina Faso.

The 250 adult lions now exist in four remote and severely endangered populations. Only one of those populations comprises of more than 50 lions.

West African lions were once widespread across Senegal to Nigeria. When researchers from West Africa, the U.K., Canada and the United States set out on the survey, they presumed that the lions existed across the 11 nations for the last two decades.

"When we set out in 2006 to survey all the lions of West Africa, the best reports suggested they still survived in 21 protected areas. We surveyed all of them, representing the best remaining lion habitat in West Africa," Philipp Henschel, Panthera's Lion Program Survey Coordinator and co-author of a paper, in a press release.

"Our results came as a complete shock; all but a few of the areas we surveyed were basically paper parks, having neither management budgets nor patrol staff, and had lost all their lions and other iconic large mammals," Henschel said.

West African lions are genetically different from their counterparts of East and southern Africa. These lions are known to be closely related to the extinct Barbary lion of North Africa and the last surviving Asiatic lions in India.

"West African lions have unique genetic sequences not found in any other lions, including in zoos or captivity," said Christine Breitenmoser, the co-chair of the International Union for the Conservation of Nature (IUCN)/SCC Cat Specialist Group. "If we lose the lion in West Africa, we will lose a unique, locally adapted population found no-where else. It makes their conservation even more urgent."

Researchers feel that surveys focusing on lion population become useless because of the rapidity at which their population declines.

"Every survey we do is inaccurate because as soon as you complete it, it is already out of date; the declines are so rapid," said Dereck Joubert, co-founder of National Geographic's Big Cats Initiative. "It is a terribly sad state of affairs when you can very accurately count the lions in an area because there are so few of them. This is critical work that again confirms that we are underestimating the rate of decline of lion populations and that the situation requires a global emergency intervention."

The paper, 'The lion in West Africa is critically endangered' has been published in the journal PLOS One.