This species is threatened by forest conversion and opportunistic collection for pet trade on Sumatra, where both of these threats extend to populations in national parks and protection forests (O?Brien et al. 2004). Between 1995 and 2000, almost 40% of the habitat for this species on Sumatra was damaged or destroyed by logging, road development (barrier and hunting) and conversion to agriculture or plantations (O?Brien unpubl. data). Legal logging seems to be accelerating in Sumatra (Geissmann et al. 2006). Forests, where they remain, are extremely fragmented. Coffee plantations present an increasing threat (O?Brien and Kinnaird 2003). The siamang is one of the most heavily traded gibbon species for illegal pet trade (V. Nijman pers. comm.).