Lion populations could be halved across much of the African continent within 20 years, with those in west Africa in danger of being wiped out due to hunting and humans' increasing need for cultivated land, a new study says.
The 20-year study, to be published by the US Proceedings of the National Academy of Sciences (PNAS) journal, sounds the alarm over the future of Africa's estimated total of 20,000 of the big cats.
The only exceptions are the intensively managed populations in the southern countries of Botswana, Namibia, South Africa and Zimbabwe, where lion numbers are increasing.
The researchers estimate that in the mid-20th century there were around ten times the present number of lions, 200,000 spread throughout Africa.
"Many lion populations are either now gone or expected to disappear within the next few decades, to the extent that the intensively managed populations in southern Africa may soon supersede the iconic savannah landscapes in East Africa as the most successful sites for lion conservation," the study said.
Study co-author Philipp Henschel, lion survey coordinator for the New York-based Panthera conservation group, said that lions can now be found in just a quarter of the territory which they used to roam.
The situation in western Africa is the most critical, the study found.
Based on the kind of drop in numbers since 1990, the lions of west Africa -- where only two large groups now live, one in Cameroon and the other on the Benin, Burkina Faso and Niger borders -- are expected to be cut in half within 20 years.
"Already recognized as critically endangered in West Africa, our analysis supports listing (lions) as regionally endangered in Central and East Africa," where they are currently classified as "vulnerable", the report's authors said.
The disappearance of the iconic big cats is due mainly to humans, either through their cultivation or hunting -- as highlighted recently by the case of Cecil the lion.
Cecil's death during a hunt arranged for a US dentist provoked worldwide outrage after it turned out that the lion was a well-known attraction among visitors to Zimbabwe's Hwange National Park and was wearing a tracking collar as part of an Oxford University research project.
Some lions are killed for their skins, or for use in traditional Chinese medicine -- sometimes in place of tiger bone, which has become very rare.
It will take great effort to protect the big cats, and above all money, according researchers.
"A recent study showed that it takes around $2,000 dollars per square kilometre per year to properly protect the lions," said Henschel.