Silvered Leaf Langur

As their name suggests, silvered leaf langurs feed primarily on leaves, preferring young, tender growth. They also eat fruits, seeds, shoots, flowers, and buds. An enlarged stomach and extra-long intestinal tract allow langurs to digest an all-plant diet more efficiently. Their guts are also loaded with a combination of enzymes and bacteria that break down plant fibers and neutralize the toxic compounds that sometimes protect seeds and leaves.

At the Zoo, langurs receive tree leaves, lettuce, peas, squash, peppers, tomatoes, potatoes, broccoli, and occasionally carrots or corn. Food enrichment may include flavored gelatin and puffed wheat cereal.  

Silvered leaf langurs are found throughout southeastern Asia and Indonesia, including the Malayan Peninsula, Borneo, Sumatra, Java, and Thailand. 

Primarily inhabiting dense forests, but this can vary depending on region. They have been found in the trees of mangrove, swamp, bamboo, and inland forests.  

Predators include snakes, tigers, leopards, and jackals. Because the monkeys are largely arboreal, they rarely leave the safety of the trees.  

Silvered leaf langurs are threatened by habitat destruction caused by increasing human presence – specifically land cleared for palm oil plantations and forest fires. In some areas, they are still hunted as a source of meat or are captured for the pet trade. 

The silvered leaf langur gets its name from the coloring of its coat. Although there is some variation in the fur color, including brown, gray, brownish-gray, or black, all individuals have some hairs that are gray-white and give a silver appearance. Males and females are difficult to distinguish from one another. The only visible difference is irregular white patching on the inside of a female’s hips. Newborn silvered leaf langurs look considerably different than adults, as they have bright orange fur with white hands, feet, and face . This is believed to help them hide from predators such as leopards, who see orange as green. The skin changes to black within days of birth, whereas the orange fur changes to the adult color after three to six months.

These monkeys have long limbs with hairless hands and feet used for grasping. They move from branch to branch using a swinging motion called “brachiation”. Their tail is considerably longer than their body, which provides excellent balance while climbing and resting in the canopy.

The reproduction of silvered leaf langurs has not been widely studied, but some facts are known. Breeding groups consist of one adult male who defends and mates with multiple females. Generally, all offspring in that group belong to that same dominant male. Breeding season can occur year-round, but there is a peak birthing season from December to May. This seems to coincide with the increased availability of food sources.

Females are pregnant for 6 to 7 months, generally giving birth to no more than one infant per year. Twins rarely occur. Newborn silvered leaf langurs look considerably different from adults, with bright orange fur and white hands, feet, and faces. The skin changes to black within days of birth, whereas the orange fur changes to the adult color after three to six months. Babies are born with their eyes open and strong forearms, allowing them to cling to their mother and she climbs throughout the canopy. Langurs participate in alloparenting, which means females and males commonly care for the young of others in the group. This includes teaching, playing, and protecting them from danger. Once fully matured, the juvenile monkeys generally disperse from the group they were born in. Females reach sexual maturity at four years of age, whereas males mature between 4 and 5 years of age. 

Silvered leaf langurs can make 13 different vocalizations, which are most common at dusk and dawn. They vocalize to signal conflict, fear, warnings, alarms, and salutation. In addition to these vocalizations, males make threatening calls and young call for their mothers. Although members of the species are relatively quiet, individuals also communicate non-vocally with each other through social play, grooming, and light fighting. 

These diurnal monkeys are active during the day and sleep through the night—the whole group sleeps in a single tree.  Langurs are generally described as a shy species, rarely being seen close to human settlements. Occasionally, they come down to the ground, but retreat quickly to the trees if there is a threat of danger.  The entire troop takes turns holding and caring for babies, called allomothering.