Jul 1

The Sumatran tiger, a Critically Endangered tiger subspecies, may be even rarer than previously thought, according to a new study.

Photo of Sumatran tigress

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.”

Photo of a male Sumatran tiger

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.”

Tiger conservation

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.

Photo of Sumatran tiger at river

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.

 

Read more on this story at Mongabay and Science Daily.

View more photos and videos of tigers on ARKive.

Liz Shaw, ARKive Text Author

Jun 29
Photo of Sumatran orangutan with infant

Sumatran orangutan (Pongo abelii)

Species: Sumatran orangutan (Pongo abelii)

Status: Critically Endangered (CR)

Interesting Fact: The name ‘orangutan’ means ‘person of the forest’.

The Sumatran orangutan lives almost exclusively in trees, only very rarely coming down to the ground. This large Asian ape is found in lowland tropical rainforests and swamps in northern Sumatra, and feeds mainly on fruit, although it will also eat leaves, termites, and even occasionally the meat of slow lorises. The Sumatran orangutan is distinguished from the Bornean orangutan by its narrower face, longer beard and lighter fur, and the two species also behave slightly differently. Adult male orangutans are larger than females, and may have large cheek pads on either side of the face. Orangutans are long-lived and breed very slowly, with females only producing an infant around once every eight years, giving them the longest inter-birth interval of any land mammal.

The main threat to the Sumatran orangutan is the loss of vast areas of forest due to illegal logging, mining and conversion to agriculture, particularly oil palm plantations. Forests have also been fragmented by roads, and forest loss and fragmentation make orangutans more vulnerable to being captured for the illegal pet trade. This species’ slow reproductive rate makes it very difficult for its populations to recover from any losses. The Sumatran orangutan is fully protected by law and is listed on Appendix I of CITES, which bans international trade in this species. However, the key to saving this charismatic primate lies in protecting its remaining forest habitat. A major stronghold for the Sumatran orangutan lies in the Leuser Ecosystem Conservation Area, and projects are also underway to rescue and rehabilitate orangutans that have been orphaned or confiscated, and, if possible, to return them to the wild.

 

Find out more about orangutan conservation at the Orangutan Foundation and Great Apes Survival Partnership.

You can also find out more about Sumatra and its wildlife on the ARKive Indian Ocean islands page.

See images and videos of the Sumatran orangutan on ARKive.

Liz Shaw, ARKive Text Author

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