Photo by Roy Terlien
Many wildlife species are threatened by shrinking habitat. But according to new research published today, the potential range of African elephants could be more than five times larger than its current extent.
Because of human pressure over the last two millenia, African elephants have suffered dramatic population declines, and their range has shrunk to just 17 percent of what it could be, say researchers - including members of Oxford University's Department of Zoology - behind the new study in Current Biology.
The dramatic reduction in range is due to the killing of elephants for their ivory and the encroachment of humans into elephant habitat. Evidence for elephants being drastically reduced in certain regions by the trade in tusks goes back to Ancient Roman times, but reached new levels from the seventeenth century onwards with the arrival of European traders and colonizers in Africa who fed the demand for ivory.
We looked at every square kilometre of the continent. We found 62% of those 29.2 million square kilometres is suitable habitat
If released from the threat of being killed for their ivory, elephants still have great potential for recovery into areas where the human footprint is light. The study found that 62 percent of Africa, an area of over 18 million square kilometres (bigger than the whole of Russia), still has suitable habitat for elephants. This huge zone includes areas where there is still room for peaceful coexistence between humans and elephants, as well as those where they could potentially live but where conflict with people may make it unrealistic.
The work was coordinated by Save the Elephants and included researchers from the Mara Elephant Project, the University of British Columbia, Oxford University, Colorado State University, the Wildlife Conservation Society, the University of Stirling, and Elephants Alive.
The team used data from GPS tracking collars and satellite imagery to undertake an in-depth investigation into where elephants roam, and why. By looking at the extremes of where modern-day elephants live, they learned where elephants had the potential to inhabit today.
The study’s lead author Dr Jake Wall, the director of research and conservation at the Mara Elephant Project in Kenya, said: 'We looked at every square kilometre of the continent. We found 62% of those 29.2 million square kilometres is suitable habitat.'
Combining three powerful tools: GPS telemetry, continent-wide remote sensing at a fine resolution, and a suite of analytical techniques, has allowed us to see what factors now control the movements and lives of these two hugely ecologically important species
To analyse the suitability of habitats over the entire continent at a kilometre-level scale, Wall and his colleagues drew on data from GPS tracking collars fitted to 229 elephants across Africa by Save the Elephants and its partners over a 15-year period. Using Google Earth Engine, a satellite-imagery computing platform, the researchers looked at the vegetation, tree cover, surface temperature, rainfall, water, slope, aggregate human influence, and protected areas in the areas the elephants traversed. This allowed them to determine which habitats can support elephants, and the extremes of conditions that they currently can tolerate.
Dr. Samantha Strindberg, a WCS Wildlife Statistician and co-author of the study, said: 'Combining three powerful tools: GPS telemetry, continent-wide remote sensing at a fine resolution, and a suite of analytical techniques, has allowed us to see what factors now control the movements and lives of these two hugely ecologically important species - and where, if circumstances change, they could range more widely across their historical African home.'
Future work aims to further refine the model with regard to the density of human impact that is viable for coexistence between people and elephants, and to include the connectivity of habitat to other areas of elephant range.
The huge areas of potential habitat include the Central African Republic and the Democratic Republic of Congo, whose forests recently held hundreds of thousands of elephants but today hold only an estimated 5,000-10,000.
The study also highlighted the extreme habitats that African elephants do not visit.
The major no-go areas include the Sahara, Danakil, and Kalahari deserts, as well as urban centres and high mountaintop
Iain Douglas-Hamilton, the founder of Save the Elephants and Senior Research Associate at Oxford's Department of Zoology, said: 'The major no-go areas include the Sahara, Danakil, and Kalahari deserts, as well as urban centres and high mountaintop. That gives us an idea of what the former range of elephants might have been. However, there’s a dearth of information about the status of African elephants between the end of Roman times and the arrival of the first European colonizers.'
Some evidence from antiquity has survived: Hanno, a Phoenician navigator, saw elephants on Africa’s Atlantic coast around 500 BCE, the ancient Greek historian Herodotus wrote in 430 BCE that elephants were reported in woodlands in present-day Tunisia, and a recently discovered sixteenth-century Portuguese shipwreck contained tusks from at least 17 different herds of forest elephants with distinct genes. All but four of those distinctive gene types are now extinct. Coupled with historical data such as this, the new model suggests elephants once occupied most of the continent.
Adult elephants’ main predator in the wild are people and elephants avoid humans by concentrating as far from human activity and influence as possible, which is usually in protected areas.
Douglas-Hamilton said: 'Elephants are quick to recognize danger, and find safer areas. The tracking data reveals that elephants living in protected areas tend to have smaller home ranges, probably because they feel unsafe ranging into unprotected lands.'
The study notes that approximately 57 percent of current elephant range is outside of protected areas, highlighting the limited space presently reserved for their safety. To secure long-term survival of elephants, habitat protection, protection of elephants themselves from illegal killing and an ethic of human-elephant coexistence will be essential.
Elephants are quick to recognize danger, and find safer areas. The tracking data reveals that elephants living in protected areas tend to have smaller home ranges, probably because they feel unsafe ranging into unprotected lands
Wall concludes: 'Elephants are generalist mega-herbivores that can occupy fringe habitats,” “Their range may have shrunk, but if we gave them the chance, they could spread back to former parts of it.'
Key findings from the study include:
- In antiquity, elephants likely were extant across nearly the entire continent.
- Human activity largely shapes the behaviour and distribution of modern elephants.
- 62 % of Africa has suitable habitat for elephants, but the animals use just 17% of that habitat and are absent – for now – in the remaining 83%.
- Savannah elephants have larger ranges than forest elephants.
- Males of both savannah and forest elephants have larger ranges than females.
- Approximately 57% of the elephant range is currently outside of protected areas.
- Out of all the factors influencing elephant range, it is human influence and the amount of protected area that had the greatest effect.
- Both an ethic of human-elephant coexistence, and effective protected areas, are essential to securing their future.