The Nepal gray langur lives in cohesive multi-male, multi-female groups where social structure is largely governed by physical condition and age. They are social animals that live in groups of about 4-47 individuals, with 1-4 adult males. All-female groups and solitary males have also been spotted. Their home range is quite extensive, around 3,150–31,380 acres (1,275–12,700 ha).

Nepal gray langurs begin foraging early in the morning, with peak feeding activity between 9 a.m. and noon. They rest during the hottest parts of the day. During this period, juveniles play, while adults engage in social behaviors such as allogrooming (cleaning each other’s fur) and autogrooming (self-cleaning). Adults may also engage in geophagia as their food is being digested.

Across all categories — adult males, adult females, subadults, and juveniles — resting accounts for up to 50% of the day, with juveniles resting slightly less than adults. Around 30% of their day is devoted to moving, followed by feeding, which takes 40% of their day. Females tend to rest more compared to males, while youngsters rest significantly less. Social behavior, including grooming, takes up to 20% of juveniles’ day, while adults spend around 10% of their day interacting with others. Females groom other members of the group more often than males. Playful behavior, instead, is only typical of juveniles or subadults, with adults hardly ever playing.

Male dominance relationships are central to troop dynamics, particularly in relation to access to females and reproductive opportunities. Their social dominance follows a chain-of-command logic with an alpha ruling over different betas, who themselves follow their own internal hierarchy.

Typically, young adult males (7–9 years of age) hold the highest ranks. Subadult males rank the lowest, while older males often decline in rank as physical strength wanes. In addition to age, physical condition plays a crucial role: males in better shape tend to have higher ranks. Coalitions among males are absent — every langur for himself.

There are two main tactics males use to become alpha:

Immigration — This is the most common route. A male from outside the group enters and, through aggressive encounters, overthrows the current alpha. This high-risk tactic is favored by younger, stronger individuals. They tend to have long-lasting reigns.

Residency or Succession — Less frequently, a long-time resident male ascends to alpha status when more dominant males emigrate or die. There’s less physical risk, but it is also less effective. This leads to shorter reigns and fewer offspring.

Some males are pretty tough rulers. These “hyper-aggressive” individuals actively stalk, chase, and attack other group members, creating an atmosphere of high tension. While they tend to maintain their alpha status longer, they are not notably more successful in siring offspring. Aggression may secure dominance, but not necessarily reproductive success.

Females tend to coexist peacefully and form their own hierarchy. Groups are mostly composed of mothers and their daughters, which creates naturally strong, kin-based bonds. Older females are typically higher ranking and have produced much of the troop’s offspring, giving them the widest network of social relationships.

Subadult females groom others more frequently and act as the “glue” of the social network. Grooming reinforces bonds, and the groomer can gain social favor from the individual being groomed.