The Sumatran tiger, a Critically Endangered tiger subspecies, may be even rarer than previously thought, according to a new study.
Found only on the Indonesian island of Sumatra, the Sumatran tiger may number fewer than 400 wild individuals and is perilously close to extinction. In a new study, published in the journal Oryx, researchers from Virginia Tech and WWF used camera traps to estimate tiger density in previously unsurveyed habitats on Sumatra.
Worryingly, they found that tiger density may only be half what has been estimated in the past, and in some areas it could be as low as one tiger per 40 square kilometres.
Tigers under threat
The main reason for the low density of tigers on Sumatra appears to be human activity, particularly large-scale conversion of forest for oil palm, pulp and paper plantations.
“We believe the low detection of tigers in the study area of central Sumatra was a result of the high level of human activity – farming, hunting, trapping, and gathering of forest products,” said Sunarto, the lead author of the study. “We found a low population of tigers in these areas, even when there was an abundance of prey animals.”
Sumatra lost around 36% of its forest cover between 1990 and 2010, but the results of the study show that tigers fare badly even in areas where the forest is apparently intact.
According to Sunarto, “Tigers are not only threatened by habitat loss from deforestation and poaching; they are also very sensitive to human disturbance. They cannot survive in areas without adequate understorey, but they are also threatened in seemingly suitable forests when there is too much human activity.”
The findings of the study highlight the importance of protecting large areas of remaining forest and reducing the levels of illegal human activity. Opportunities still exist to protect some of the region’s forests, but without urgent action they could soon be converted to plantations.
It will also be important to find ways to improve tiger habitat while also supporting local people, for example through agroforestry activities or selective logging. As the rapid conversion of forests to oil palm plantations is driven by high global demand, the international community also needs to take responsibility for protecting Sumatra’s forests and its tigers.
Although the results of the study are worrying news for the Sumatran tiger, the team found a potentially stable tiger population in the region’s Tesso Nilo National Park, showing that legal protection can be effective in reducing human impacts and allowing the tiger population to recover.
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Liz Shaw, ARKive Text Author