Despite extensive conservation efforts, wildlife populations continue to decline globally, largely driven by human activities such as habitat loss and illegal resource extraction. Timber poaching represents a relatively understudied but significant threat to forest ecosystems and arboreal wildlife. This study investigates the ecological and socio-economic dimensions of timber poaching in the Hoollongapar Gibbon Wildlife Sanctuary (HGWS), Assam, India, with a particular focus on its implications for the endangered western hoolock gibbon (Hoolock hoolock). The research adopts an interdisciplinary framework integrating remote sensing analysis, vegetation surveys, behavioural observations, and ethnographic investigation to examine conservation challenges across ecological and human systems.

Land Use and Land Cover (LULC) analysis using satellite imagery (2017–2023), supported by field validation in 2025, revealed that although HGWS remains largely forested, gradual landscape transformation is occurring. Tree cover declined modestly, while built infrastructure and other anthropogenic features increased, indicating expanding human influence within the sanctuary landscape. Vegetation surveys across 20 dominant plant species further revealed spatial heterogeneity in tree diversity and canopy structure across forest compartments, reflecting variation in habitat quality and resource distribution.

Field surveys documented 31 timber poaching sites, with the southern region of HGWS exhibiting particularly high extraction pressure. Poachers often exploit a legal loophole in the Wildlife (Protection) Act of 1972, which criminalises tree cutting but not the collection of fallen wood. By cutting V-shaped notches into tree trunks, they weaken trees and cause them to collapse under natural stress, allowing the timber to be collected as “fallen wood.” This covert practice complicates enforcement, as forest guards often struggle to distinguish between legitimate resource collection and deliberate timber extraction.

Behavioural observations totalling approximately 143 hours revealed significant behavioural plasticity in gibbons. Moderate disturbance levels were associated with increased vigilance, alarm vocalisations, and adaptive adjustments in foraging behaviour, whereas high disturbance suppressed key behaviours, including alarm communication and coordinated group movement. Population surveys recorded thirty gibbon groups across the sanctuary, with evidence of ongoing reproduction despite disturbance.

Ethnographic research revealed widespread forest dependence among local communities, with livelihood constraints and limited economic alternatives emerging as major drivers of timber extraction. The findings highlight complex interactions among habitat change, wildlife behaviour, and human livelihoods. By integrating ecological and socio-economic perspectives, this study provides new insights into disturbance ecology and emphasises the need for targeted, community-informed conservation strategies to safeguard the diversity of HGWS.