For a large, charismatic, and endangered species such as the Asian elephant, you might think scientists would have figured out where they hang out and when. But it turns out, there's very little evidence-based information on their distribution across countries in Asia. Researchers in Sri Lanka, however, are filling in some of this information gap.
By conducting interview surveys across the island nation over four years, researchers have now produced a countrywide, data-based distribution map of Asian elephants for the country. This isn't just Sri Lanka's first such map, the researchers say in a new study published in Oryx—it's also the first evidence-based distribution map of Asian elephants for any of the 13 range countries. Previous distribution estimates either covered smaller areas within host countries, or were based on "guesswork and conjecture," the researchers say.
To find out where elephants occur in Sri Lanka, Prithiviraj Fernando, an elephant expert at Sri Lanka's Centre for Conservation and Research, and his colleagues divided the country into a grid with nearly 2,750 cells, each 9.7 square miles in area (the cell size was based on the smallest known home range of Sri Lankan elephants). Then, between 2011 and 2015, the researchers interviewed three residents per grid cell. If a cell didn't have any residents, such as those that fell within a protected area, the team estimated the presence of elephants based on the four adjoining cells. The team also validated some of the interview data using GPS locations of elephants that the researchers tracked from 2004 to 2018.
In all, the researchers found that elephants currently occur across 60 percent of Sri Lanka, a figure that's higher than previous estimates based on expert opinions. This is also a much higher percentage than that of any other range country, Fernando says.
The majority of Sri Lanka's elephants live outside protected areas, the study found. There, they jostle for space with humans in landscapes consisting of forests and scrubland intermixed with farmland and villages and towns.
"This study documents in a very robust way something that has been known for a long time—the fact that elephant populations depend on land outside protected areas. So in that sense, this is nothing surprising," says Shermin de Silva, a conservation biologist and director of the Uda Walawe Elephant Research Project, who was not involved in the study. "But what is interesting is that it quantifies just how much area the range actually covers, and it seems to be far greater than prior estimates."
Most elephant habitat in Sri Lanka is contiguous, which means the elephants are one continuous population, the study found. "Because it is one population it is more resilient and has a better conservation outlook than if it was fragmented, so it is very important to make sure it remains so," Fernando says.
Much of southwestern Sri Lanka, however, known as the "wet zone," is heavily developed and densely populated, and thus has virtually no elephants. There are only two isolated populations of elephants there, one in Peak Wilderness Sanctuary and another in Sinharaja Forest Reserve. These two populations, Fernando says, are the "last of the wet zone elephants."
"The Sinharaja population is all but extinct with only two males left," he says. "From a conservation point of view what should be done is to try and revive these populations and prevent them going extinct. However, there is no likelihood there will be any effort in that direction."
The Sri Lankan elephants also seem to have lost around 16 percent of their range in the past 55 years, the study found, suggesting that their population may actually be declining. Moreover, wherever the elephants do co-occur with people, there is intense conflict, the study found.
For an elephant population that occurs predominantly outside protected areas in space shared with humans, trying to confine the animals to the limits of protected areas is not a sound conservation strategy, the researchers say. Such an approach, which typically involves driving the elephants away, only leads to an escalation of conflict, they add.
Instead, the authors recommend a "human-elephant coexistence model," one that aims to reduce conflict by protecting villages and cultivations with barriers such as electric fences. "This approach has been incorporated into the National Policy for Elephant Conservation and Management in Sri Lanka but is yet to be fully implemented," they write in the paper.
"The fact that elephants currently seem to be sustaining themselves in highly disturbed, human-modified landscapes indeed argues for devoting more attention and resources to managing these landscapes in a manner compatible with conservation," de Silva says. "But it would be dangerous to suggest that such landscapes might actually be more suitable for elephants than the large un-fragmented wildlands that would have constituted the bulk of elephant habitat until quite recently."
De Silva says the distribution of conflicts and conflict-related mortality showed that elephants pay a heavy price for living near people. "In many areas what we could be seeing is a situation in which elephants, being long-lived, enduring in an environment that changed rapidly within their lifetimes, but which may not sustain future generations," she says. "The authors do point out that there is a lag period between development and population extinction, but don't seem to fully recognize its implications for these findings."
This story originally appeared at the website of global conservation news service Mongabay.com. Get updates on their stories delivered to your inbox, or follow @Mongabay on Facebook, Instagram, or Twitter.