Slow lorises are one of three species of loris maintained at the Lemur Center (the others are pygmy slow lorises and slender lorises). All three of these species are members of the family Lorisidae which includes lorises, galagos and pottos and consists of 9 genera and over 25 species found in Africa south of the Sahara, southern India, Sri Lanka, southeastern Asia and southwestern China. Lorises have a tail either very short or completely absent, and their heads and eyes are round, with small ears which are almost completely hidden by fur. The forelimbs and hindlimbs of lorises are nearly equal in length.
All lorises have extremely strong fingers and toes, and they are capable of maintaining a powerful grip with either hands or feet for astonishingly long periods of time. They are arboreal and nocturnal, sleeping by day in hollowed out trees, tree crevices or branches. Generally they sleep curled up in a ball, with their heads tucked up under their arms. When they move, they do so with slow deliberate hand-over-hand movements, moving along as easily under a branch as above. They are capable of moving quickly if alarmed, but they do not jump or leap.
In North America, there are approximately 30 slow lorises in captivity. The DLC no longer houses any slow lorises.
The slow loris does all of its feeding at night, moving stealthily and deliberately through the darkness. As with other lorises, this species is an arboreal feeder that prefers to forage alone.
These animals are omnivorous, eating many different types of plant and animal material. Fruits and gums make up more than 50% of the diet, but insects and small prey items are a valuable food item also (making up about 30% of the diet). Lorises use their acute sense of smell to locate prey in the dark. Because they are larger and more widely distributed than the pygmy slow loris, slow lorises get their protein from a greater variety of meat sources. Apart from insects, they have been known to eat mollusks, eggs, lizards, birds, and even small mammals.
While this species may look very slow, it is capable of short bursts of very rapid movement when catching prey. They lunge at insects by clinging to a branch with their hind legs, then springing forward and snatching their quarry with both hands. They may then hang upside down to eat.
Slow lorises breed every 12 to 18 months, at a time of year when seasonal food levels are rising to a maximum. Females may come into estrus at any time of year. When in estrus they make frequent high-pitched whistles to attract a mate. After a gestation period of 191 days, females give birth to one or two offspring. Birth often occurs in the animals’ nest, but may occasionally take place in the open. Infants are always parked or left in the nest while the mother forages. Newborn infants have grey bodies and silvery-white hands with long glistening fur that disappears at 11 weeks. If accosted, slow loris babies can produce ultrasounds to alert their parents. It has been hypothesized that adult slow lorises can produce a toxic saliva, and they will lick their young to protect them from predators. At 11 weeks, infants’ coats darken to their adult colors. The offspring are weaned at six months of age, and reach sexual maturity between 17 and 21 months.
Because they are nocturnal and not widely distributed throughout their range, the social behavior of slow lorises has historically been difficult to study. Nonetheless, several studies have been conducted and are now invaluable sources of information.
Males and females generally forage separately, coming together only to breed. Females leave their young behind when they venture out in search of food. As such, the slow loris is considered to be a solitary species, although family groups have occasionally been found together.
Males are suspected to have a slightly larger home range than females, and are considerably more territorial. Lorises communicate with each other by urine-marking, a process in which they urinate on their hands and then wipe them on branches. (It is also thought that this makes their hands sticky and thus allows them to grasp better). Urine marks apparently convey important messages to others, as well as staking out each animal’s territory, so that individuals almost never cross paths.
Slow lorises can produce a variety of sounds, ranging from a low hiss or growl when disturbed, to a high whistle made by females in estrus. Animals may also scent mark themselves when under stress, using glands on the underside of their arms.
Slow lorises occupy a wide range across southern Asia and western Indonesia, including parts of India, Myanmar, China, Thailand, Vietnam, Laos, Cambodia and Indonesia. They are generally found high in the trees in tropical rainforests, preferring warm, lowland areas below 1300 meters (4265 ft.) in elevation. Slow lorises are perhaps the most edge-adapted of the loris species, staying near the rainforest boundaries where there are more vertical supports and more insect prey.
Due to their nocturnal lifestyle and politically restricted access to their home range, it has been difficult to determine exactly how many slow lorises remain in the wild. What is known is that they are not well-distributed within their home range, and they face stiff competition from arboreal monkeys in areas where the two overlap.
We also know that they are facing the consequences of rampant environmental destruction. In Indonesia, it is believed that two-thirds of the animals’ habitat has been lost to logging and agricultural pursuits. Similar activities in southeastern China have reduced the number of individuals there to only a few hundred. Furthermore, slow lorises are threatened by hunters, who prize them for their fur and for use in traditional medicine.
Lorises also face tremendous threat from capture for the illegal exotic pet trade. They are subjected to terrible living conditions, illness and malnutrition, and often have their teeth pulled to avoid bites before being sold illegally. Lorises often die in street markets or while being smuggled out of their home country. Popular Internet pictures and videos show lorises as pets behaving in ways their owners find “cute,” but the behaviors are reactions to stress and fear. Popular practice in busy tourist destinations in southeast Asian countries is to have lorises for tourists to hold for photos, while the loris’ large nocturnal eyes are subjected to bright city lights. Pet lorises are often made to be active during the day although their natural cycle is to be active at night.
Order: Primates; Suborder: Prosimii
Superfamily: Lorisoidea; Family: Lorisidae
Genus: Nycticebus; Species: coucang
The pygmy slow loris (Nycticebus pygmaeus) is sympatric with the slow loris in parts of its range, and is similar in behavior to the slow loris.
Adult Size : 1.8 – 2.9 pounds
Natural Range : Southeast Asia and western Indonesia, southwestern China
Social life : Solitary nocturnal forager
Habitat : Tropical evergreen forests, secondary forests, and suburban gardens
Diet : Mainly fruit, with occasional insects and bird eggs
Lifespan : up to 20 years in captivity
Sexual maturity : 18 months
Mating : Once every 12 – 18 months
Gestation : 191 days
Number of young : 1 – 2 offspring every 1 – 1 ½ years
DLC Naming theme : Indian gods and goddesses (Mitra, Chandra, Kedar, etc.)
Interesting Facts :
- Slow lorises sleep rolled up in a ball with their head between their legs.
- Slow lorises often hang upside-down from branches by their feet so they can use both hands to eat.
- The grasp of a slow loris is so strong that it can freeze in one position for hours as it stalks its prey.