(AFP) - Decades of poaching and shrinking habitats have devastated elephant populations across Africa, conservationists said Thursday, warning that one sub-species found in rainforests was a step away from extinction.

In an update of its "Red List" of threatened species, the International Union for Conservation of Nature (IUCN) highlighted the broad deterioration of the situation for elephants in most of Africa.

Forest elephants on the continent had been particularly hard-hit, it said. Their numbers have fallen by more than 86 percent over three decades, and they are now considered "critically endangered" -- just a step away from becoming extinct.

The population of the African savanna elephants had meanwhile decreased by at least 60 percent over the past 50 years, IUCN said, with the Red List now listing that species as "endangered".

Previously, elephants on the continent were assessed as a single species considered vulnerable, but not endangered.

"Today's new IUCN Red List assessments of both African elephant species underline the persistent pressures faced by these iconic animals," IUCN chief Bruno Oberle said in a statement.

Just half a century ago, around 1.5 million elephants roamed across Africa, but in the most recent large-scale assessment of population numbers in 2016, there were only around 415,000 remaining.

- 'Wake-up call' -

"These are really sharp declines," said Benson Okita-Ouma of Save the Elephants and the co-chair of the IUCN African Elephant Specialist Group.

While the next full assessment of African elephant population numbers is not expected until 2022 or 2023, he told AFP that the declines seen already should really sound "alarm bells".

Elephants will not disappear from Africa overnight, he said, but stressed that "what this assessment is giving us is an early warning that unless we turn around things, we are likely to (see) these animals go extinct".

"It is a wake-up call to the entire globe that we are going down a steep terrain, when it comes to... the viability of these elephants."

Experts had agreed it was better to treat African forest and savanna elephants as separate species following fresh research into the genetics of the elephant populations, IUCN said.

Forest elephants are found in the tropical jungles of Central Africa and in various habitats in West Africa, and are thought to occupy currently only a quarter of their historic range.

The largest remaining populations are found in Gabon and the Republic of Congo.

The savanna elephant meanwhile prefers open country and is found in a variety of habitats in sub-Saharan Africa.

- Poaching explosion -

Both elephant species had seen particularly sharp declines since 2008, as poaching for ivory exploded.

The problem peaked in 2011, but continues to threaten populations, IUCN said.

Perhaps even more alarming, according to Okita-Ouma, is the ever-increasing destruction of elephant habitats due to expanding land use for agriculture and other activities.

"If we don't plan our land-use properly, moving forward, then as much as we stop poaching and we stop illegal killing of these animals, there will still be other forms of indirect killings as a result of poor land-use planning," he said.

Despite the overall declining trend, Thursday's report highlighted the positive impact conservation efforts can have.

Some forest elephant populations have stabilised in well-managed conservation areas in Gabon and the Republic of Congo.

And savanna elephant numbers have been stable or growing for decades in the Kavango-Zambezi transfrontier conservation area that stretches across the borders of five southern African countries.

"Several African countries have led the way in recent years, proving that we can reverse elephant declines, and we must work together to ensure their example can be followed." Oberle said.

Okita-Ouma said the Covid-19 pandemic was taking a toll on conservation efforts as many countries had seen tourism revenues used to fund protection measures evaporate.

At the same time, he said, the dramatic decline in human activity in many areas had allowed elephants to "recolonise" areas they had previously been driven from.

"During the lockdowns, we have seen animals moving all over, and that is a positive side for the animals."

© Agence France-Presse