6-7-2024 ROTTERDAM ZOO, NETHERLANDS - LION TAILED MACAQUE (Macaca silenus)

Lion-tailed macaques are covered in black fur, and have a striking gray or silver mane that surrounds their face which can be found in both sexes. The face itself is hairless and black, being pinkish in infants less than a year old. They are named not for their mane, but for their tail, which is long, thin, and naked, with a lion-like, black tail tuft at the tip. The size of their tail is about 25 cm (9.8 in) in length. Their eyes are a shade of hazelnut with highlighting black eyelids. Lion-tailed macaques, like other macaques, have deep cheek pouches useful for storing food, and are quadrupedal with opposable digits. The mane that surrounds its face gives this monkey its German name Bartaffe – "beard ape". With a head-body length of 42–61 cm (17–24 in) and a weight of 2–10 kg (4.4–22.0 lb), it ranks among the smaller macaques species. Offspring are born with lighter faces and no mane, with the adult mane growing in after two months after birth.

The lion-tailed macaque is a rainforest dweller, often being found in the upper canopy of tropical moist evergreen forests or monsoon forests. It is diurnal, meaning it is active exclusively in daylight hours. When they are active, they will spend half the day foraging, and the other half will be spent resting or finding new areas to forage. Unlike other macaques, it typically avoids humans when possible. In group behavior, the lion-tailed macaque is much like other macaques, living in hierarchical groups of usually 10 to 20 members, which usually consist of few males, typically 1-3, and many females. They have a polygynous mating system with no specific breeding season. While there is no specific breeding season, they do tend to breed in the wet season when resources are most abundant. 

Little time is spent grooming or playing with others in the group. Of the few males, only one will be the dominant male, who will protect his troop from others and be the one who breeds. It is a territorial animal, defending its area first with loud cries and bared teeth towards the invading troops. If this proves to be fruitless, it brawls aggressively, which can result in severe injuries due to lacerations from their large canines. Other forms of communication come in the form of mounting to show strength, branch shaking to scare off, lip-smacking as a friendly greeting, or yawning with a grimace to indicate dominance.

Lion-tailed macaque behavior is characterized by typical patterns of arboreal living. This patterns involve selectively feeding on a large variety of fruit trees, large interindividual spaces while foraging, and time budgets with high proportion of time devoted to exploration and feeding.

 Lion-tailed macaques are omnivores, primarily eating indigenous fruits, seeds, flowers, insects, snails, and small vertebrates in virgin forest. Lion-tailed macaques are very important for seed dispersal, and are able to transport seeds long distances by either dropping or defecating seeds. However, due to changes in their environment, adaption to rapid environmental change has occurred in areas of massive selective logging through behavioral modifications and broadening of food choices. These changes involve a large increase in ground foraging and feeding on far more non-native plants and insects. These feeding changes include fruits, seeds, shoots, pith, flowers, cones, mesocarp, and other parts of many non-indigenous and pioneer plants. In the forests of Kerala they were observed preying on nestlings and eggs of pigeons.

Gestation lasts approximately six months. The young are nursed for one year. Sexual maturity is reached at four years for females, and six years for males. The life expectancy in the wild is approximately 20 years, while in captivity is up to 30 years.