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Sumatran tigers, the world’s smallest tigers in size, may be the targets of poaching in the Ulu Masen ecosystem, one of Southeast Asia’s last wildernesses in the Indonesian province of Aceh, a new research paper has suggested.
The researchers reached this conclusion after analysing camera trap data for two years. It revealed a stark gender difference between males and females.
“Ulu Masen ecosystem (738,000 ha) of the Aceh Province is one of the last vast wildernesses in South East Asia. IUCN categorized areas under Category VI as protected areas, primarily due to their unique cultural values and traditional natural resources management practices. It is home to the Critically Endangered Sumatran Tiger under immense pressure from habitat loss and illegal hunting,” notes the 2021 paper Current Status of Forest Management Unit Effectiveness Versus Decreasing The population of Sumatran Tigers in the Ulu Masen Protected Area, Aceh.
The researchers of the October 2024 paper stated that their estimates of tiger habitat use are the first reported for a Sumatran ecosystem unprotected at the national level.
“During 6,732 trap nights accumulated over 23 months of camera-trap monitoring in 2020 and 2022, tigers were detected 39 times at 16 of the 52 stations. We identified 11 individual tigers but sex ratios were highly skewed: 8 males, 1 female, and 2 individuals of unknown sex. Cubs were not photographed either year and we did not observe evidence of tiger reproduction,” the paper read.
While the identification of 11 tigers during the surveys of the researchers was suggestive of a sizeable tiger population in Ulu Masen, the researchers pointed to something else. “Only when accounting for site fidelity and sex ratios, do our data tell another story,” they said.
Just one female was sighted in the camera traps. According to the researchers, the absence of breeding females was a warning sign.
“The documentation of females, particularly breeding females, is a key metric for assessing the status of tiger populations and therefore integral to tiger monitoring and recovery efforts. Adult female survival is usually the strongest determinant for the growth and persistence of tiger populations. Whereas female-biased sex ratios are indicative of healthy tiger populations (considering the species’ social organization with the larger home ranges of males overlapping those of several females), high population turnover and male-biased sex ratios generally indicate severe poaching,” the paper read.
The researchers concluded that tiger-targeted protection is urgently needed to ensure the species’ persistence in Ulu Masen which, together with the adjacent Leuser Ecosystem, represents the largest contiguous tiger conservation landscape remaining in Sumatra.
Intact, under-patrolled forests harbor widespread prey but a male-biased tiger population in the Ulu Masen Ecosystem, Sumatra, Indonesia was published in Scientific Reports on October 24, 2024.