Up to 730,000 elephants are 'missing' from Africa's protected areas amid fears they have been slaughtered, a report has found.

Conservationists in South Africa have blamed 'pervasive poaching' for the dramatic reduction in numbers across 73 designated areas spanning 21 African countries.

Researchers from the Conservation Ecology Research Unit (CERU) at the University of Pretoria have called for action to protect the animals.

Up to 730,000 elephants are 'missing' from Africa's protected areas amid fears they have been slaughtered, a report has found (file picture)

Conservationists in South Africa have blamed 'pervasive poaching' for the dramatic reduction in numbers across 73 designated areas spanning 21 African countries (file picture shows ivory being torched by officials in Cameroon)

But they said the situation was not necessarily all 'doom and gloom' since the findings could serve as a global wake-up call.

Study author Ashley Robson said: 'In the past, we've had relatively good estimates of how many elephants there are and how many are poached. But now, we've determined how many elephants there should be in the first place.

'While the magnitude of loss due to poaching is devastating – 730 000 elephants are missing across the 73 protected areas assessed – I don't see our work as more doom and gloom. While the conservation targets are a positive step, our study is a wake-up call

'On the contrary, we provide ecologically meaningful goals for elephant conservationists to work toward. It's a positive step for elephants.'

Remote sensors were used to monitor vegetation and water sources used by elephant populations while poaching statistics were also taken into account when producing the figures.

Researchers, who published their findings in PLOS ONE also used the largest population database for any mammal species to model the density at which individual populations should stabilise.

Researchers from the Conservation Ecology Research Unit (CERU) at the University of Pretoria have called for action to protect the animals

Mr Robson added: 'Everyone with an interest in conservation – protected area managers, policy-makers, international funders, and the public – should consider our study.

'We've made it possible to target resources to the protected areas that have the greatest need. Of course, this isn't just for the sake of elephants; elephants play a major role in shaping the savannahs that in Africa cover as much land as the USA and continental Europe combined.

'Losing elephants is detrimental to our savannahs and the species that rely on them.

'While the conservation targets are a positive step, our study is a wake-up call.

'Around 70 per cent of the current distributional range of African elephants fall beyond protected areas. That elephants aren't doing well, even where protected, means we need to take action.'

In August, a separate study found that the number of savanna elephants in Africa was rapidly declining and the animals were in danger of being wiped out as international and domestic ivory trades drive poaching across the continent.

In August, a separate study found that the number of savanna elephants in Africa was rapidly declining and the animals were in danger of being wiped out as international and domestic ivory trades drive poaching across the continent (file picture)

Africa's savanna elephant population plummeted by about 30 per cent from 2007 to 2014 and was declining at about eight per cent a year, said a survey funded by Microsoft co-founder and philanthropist Paul Allen.

'If we can't save the African elephant, what is the hope of conserving the rest of Africa's wildlife?' elephant ecologist Mike Chase, the lead researcher, said in a statement. 'I am hopeful that, with the right tools, research, conservation efforts and political will, we can help conserve elephants for decades to come.'

The aerial survey covered 18 countries using dozens of airplanes to fly the equivalent of going to the moon and partway back. The study, known as the Great Elephant Census and involving 90 scientists, estimated a population of 352,271 savanna elephants.

Overall, researchers spotted about 12 carcasses for every 100 live elephants, indicating poaching at a high enough level to cause population decline. But the rates were much higher than that in some countries.

Angola, Mozambique and Tanzania experienced greater population declines than previously known, and elephants face local extinction in parts of the Democratic Republic of Congo, Cameroon and Zambia, the study said. It also says numbers of elephants in South Africa, Uganda and parts of Malawi and Kenya were stable or partly increasing.