Leuser ecosystem, Sumatra – A new Frontiers in Conservation Science study using infrared camera traps across three surveys indicates an important population of critically endangered Sumatran tigers may be holding on in the Leuser ecosystem on the Indonesian island of Sumatra.

“We documented a robust tiger population, apparently among the healthiest on the island,” said Dr Joe Figel. “For those on the ground, the onus now falls on us to double down and adequately protect them.”

Leuser is a major remaining tiger habitat. “It’s also more thoroughly patrolled by rangers than nearly any other place on the island,” Figel said.

The team installed cameras in northern Leuser, in Aceh province, over three monitoring periods from March 2023 to November 2024.

Across these sessions, the cameras captured 282 images that allowed identification of 27 tigers: 14 females, 12 males, and one of unknown sex. During a six-month session in 2023, three different sets of cubs were recorded, and two tiger brothers seen as cubs later appeared separately as adults.

The study area lies in forests provincially protected by the Aceh government outside Gunung Leuser National Park, which receives far fewer resources than centrally managed national parks. The camera traps placed by Figel and colleagues snapped nearly three times as many tiger images as previous 90-day surveys at other sites in Sumatra.

“Thanks to the work, activities, and support of government agencies, local Acehnese and Gayo communities, donors, and other researchers, Leuser has maintained important patches of lowland and hill forests where, in Sumatra, tiger prey densities reach their highest levels,” concluded Figel. “The persistence of these habitats and prey populations are the main reasons for our findings.”

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