野外蘇門答臘虎僅餘約 400 隻；超過 70%棲息在國家公園和保護區以外的地區，例如烏魯馬森生態系統。一項為期兩年的研究記錄到烏魯馬森生態系統裡有11 隻老虎，其中只有一隻雌性，而且第一年記錄的個體在第二年就再也沒有出現過，也沒有觀察到任何繁殖活動。牠們領域變動率高及性別比例問題顯示偷獵現象嚴重。
There are only around 400 Sumatran tigers living in the wild; over 70% of the Sumatran tigers inhabit areas outside national parks and protected areas, like the Ulu Masen Ecosystem. A two years study recorded 11 tigers in the Ulu Masen Ecosystem, among those only one female was recorded, and none of the individuals recorded in the first year were seen again in the second. No reproduction evidence was observed as well. Data shows high population turnover and sex ratios issue indicate high levels of poaching.
