The pig-tailed langur lives in Indonesia’s Mentawai Islands. A study of wild groups on Siberut found that adult males were larger on average than females and that the three groups studied averaged about nine animals.
A study of free-ranging animals on Siberut reported that adult males were larger and heavier on average than adult females.
A study of three groups in undisturbed forest on Siberut found an average group size of about nine. The researchers considered a group with several females the most likely social pattern in that setting.
An extinction-risk assessment has not been added yet.