A camera trap survey in Indonesia's Leuser ecosystem has detected more Sumatran tigers than expected, signaling potential success in conservation efforts. The study found 17 tigers in 2023 and 18 in 2024, far exceeding averages from other parts of the island. This discovery highlights the importance of ranger patrols in protecting the critically endangered subspecies.
In a previously unstudied area of the Leuser ecosystem, one of Southeast Asia's largest intact rainforests, researchers collaborated with the Gayo Indigenous people to deploy 60 camera traps. The devices captured images of 17 Sumatran tigers during a 90-day period in 2023 and 18 in 2024. These numbers more than double the average of seven tigers spotted in similar surveys elsewhere on Sumatra.
The survey identified 14 adult female tigers, 12 males, three sets of cubs, and one adult of unknown sex. Conducted over 180 days in both years, the effort provides a seasonal overview for better reliability, according to Deborah Martyr of Flora and Fauna International, who was not involved in the research.
Joe Figel of the conservation group Hutan Harimau expressed surprise at the findings. “It surpassed my expectations, just because the literature up until this study said that we weren’t supposed to find tigers in these densities,” he said. “So it was a very promising result, testament to a lot of efforts that have been going on in that region.”
The area near Gunung Leuser National Park benefits from monthly patrols by rangers funded by NGOs Forum Konservasi Leuser and Hutan Harimau, in partnership with Aceh's Environment and Forestry Service. These efforts appear to have reduced poaching, allowing prey like sambar deer to thrive and support the tiger population.
Sumatran tigers, the sole survivors of the Panthera tigris sondaica subspecies, face threats from poaching for trophies and traditional medicine, as well as logging of dipterocarp trees. Overall population estimates range from 173 to 883 due to data gaps. Figel warned of the broader crisis: “What more of a wake-up call do we need? The tiger in South-East Asia right now is really in dire straits,” citing recent extinctions in Vietnam, Cambodia, and Laos.
The study was published in Frontiers in Conservation Science (DOI: 10.3389/fcosc.2025.1691233).