Slow loris

SOCIAL ORGANIZATION AND BEHAVIOR

The N. c. coucang social system might be closest to a monogamous single male/single female social system with the pair living with offspring (Wiens & Zitzmann 2003b; Nekaris & Bearder 2007). In one study, slow lorises (N. coucang) were predominantly solitary, spending only around 8% of their active period near other slow lorises. If an individual slow loris home range overlaps with that of another, encounters are generally friendly, but not so if there is no range overlap. These friendly relations define “spatial groups” which are a unit of social organization in the species. In general, only four types of interaction are seen on a nightly basis among slow lorises in the same “spatial group.” These include allogrooming, following, pant-growling, and click-calling, and social behavior only make up around 3% of the activity budget (Wiens & Zitzmann 2003b). In captivity, allogrooming is also the most common social behavior (Newell 1971). In addition, not all individuals are members of a spatial group. Home ranges are not defended, and neither are food patches. When members of a spatial group encounter non-members, there is usually no interaction (Wiens & Zitzmann 2003b). While usually alone, adult slow lorises will sometimes sleep with up to several conspecifics, including other adult animals (Wiens 2002).

Social behaviors in varying contexts have been recorded in artificial groups of captive N. coucang. In fact, when kept together in captivity, they are quite sociable, although adult males can be very intolerant of one another and may fight, often resulting in serious injury (Ehrlich & Musicant 1977; Tenaza & Fitch 1984). In captivity, agonistic behaviors include attacks, pursuits, threats, assertion, fighting, and subordinate behaviors. Associative behaviors include close proximity, physical contact, following, social exploration, social grooming and social play (Ehrlich & Musicant 1997). In a different captive study, severe aggression included threats and attacks, and less intense aggression (staring, cringing, pant-growling and avoidance) was also seen (Daschbach et al. 1982-1983). Dominant or submissive behaviors among slow lorises are not seen in captivity (Rasmussen 1986).

In general, slow lorises disperse around 16-27 months of age, and both sexes have been seen dispersing in the wild (Wiens & Zitzmann 2003b).

REPRODUCTION

The true mating system of wild slow lorises is unknown, and may in fact be variable between populations (Wiens & Zitzmann 2003b). However, it might be best described as a monogamous single male/single female social system (Wiens & Zitzmann 2003b; Nekaris & Bearder 2007). In one anecdotal observation, several male slow lorises were seen to follow a female and attempt to mate with her (Elliot & Elliot 1967).

N. pygmaeus females show sexual swelling during estrus, during which the genitals turn reddish. Females also show behavioral estrus, increasing their approach, departure, and lunge behaviors during estrus (Fitch-Snyder & Jurke 2003). N. coucang however, only rarely show these sexual swellings (Zimmermann 1989). Males pursue estrus females around (Fitch-Snyder & Jurke 2003). Estrus cycles in N. coucang last 29-45 days, averaging 36.4 days, with copulations mostly occurring on a single day (Izard et al. 1988). Copulatory plugs are sometimes seen after N. coucang reproduction (Izard et al. 1988). Females of N. pygmaeus and N. coucang solicit copulation by hanging from a branch (often making whistling vocalizations) and copulation occurs thus, with the male grasping both the female and the branch (Zimmermann 1989; Fitch-Snyder & Jurke 2003). N. coucang also solicit copulation by walking in front of the male and urine-marking and vocalizing (Zimmermann 1989). In captivity, N. pygmaeus are seasonal breeders, with most births occurring between January and April. In the wild, they also likely breed seasonally, although the actual timing and duration is unknown (Fitch-Snyder & Jurke 2003). Contrary to this, other species of slow loris are not seasonal breeders, and instead are polyestrous (Fitch-Snyder & Jurke 2003).

Successful reproduction can happen as early as 73 weeks in captive male N. pygmaeus and sexual maturity likely occurs before 14 months of age in males of the species, although actual reproduction usually occurs around 17-20 months old (Weisenseel et al. 1998; Fitch-Snyder & Jurke 2003). Female N. coucang are sexual mature between 17-24 months old (Izard et al. 1988; Weisenseen et al. 1998). Gestation lengths for N. coucang and N. pygmaeus are similar, averaging 191-192.2 days and 188.0 days respectively (Izard et al. 1988; Weisenseel et al. 1998).

PARENTAL CARE

N. coucang births are usually singletons, although twinning has been seen (Izard et al. 1988). N. coucang infants are born with open eyes and all of their fur, with gray face, limbs, and ventrum and a brown back with a dark stripe, and can cling to their mothers one hour after birth (Zimmermann 1989; Wiens 2002). Twins are more common in N. pygmaeus than in N. coucang (Fitch-Snyder & Ehrlich 2003). Birth weights in captivity average around 48.2 g (1.7oz), and the interbirth interval is around 16.2 months (Izard et al. 1988). In captivity, N. coucang first groom themselves at four weeks of age, and show first locomotion at around 6.2 weeks old, with drinking, eating and urine marking starting at 9.3, 12.0, and 13.0 weeks respectively (Ehrlich & Macbride 1989). However, in a different captive study, eating of solid food occurred much earlier, and development was described as being extremely quick, with infants showing adult movement and social patterns soon after birth (Zimmermann 1989). Infants are carried by clinging to the mother’s fur on her ventrum, and are almost completely immobile in their first 6-8 weeks of age (Ehrlich 1974; Ehrlich & Macbride 1989). However, in the wild a four-week old infant (N. coucang) was seen to be able to climb about a food tree, albeit not adeptly (Wiens & Zitzmann 2003a). After the first week of life, mothers “park” their infants for prolonged periods, during which, the infants in many cases will not, or are unable to, follow (Ehrlich 1974; Tenaza & Fitch 1984; Ehrlich & Macbride 1989; Wiens 2002; Fitch-Snyder & Ehrlich 2003). From the second week on, infants follow their mothers (Fitch-Snyder & Ehrlich 2003). Wild N. coucang infants will only follow their mothers to a sleeping site (Wiens 2002). Between N. pygmaeus and N. bengalensis, mother-infant pairs of the former spend more time near each other, but overall, there are great similarities in the relationships between mothers and their infants across slow loris species (Fitch-Snyder & Ehrlich 2003). Overall, N. coucang maternal care consists only of suckling, carrying, and grooming (Wiens 2002). Maternal lactation persists around six months and weaning occurs between the fifth and seventh months of age (Izard et al. 1988; Zimmermann 1989).

COMMUNICATION

N. coucang emits eight different types of call used in two basic functional groups, relating to contact or affiliation (including whistles, short keckers), and those relating to aggression and defense (including snarls, grunts, long keckers, and screams) (Zimmermann 1985). Slow lorises do not emit alarm calls (Wiens & Zitzmann 2003b). Whistle calls are often heard from females in estrus (Daschbach et al. 1981). Ultrasonic vocalizations out of the human hearing range, are emitted when slow lorises explore unknown environments and during handling (Zimmermann 1981). Infants emit click sounds when they are isolated from their mother and when they feel distressed (Rassmussen 1986). Click-calls are used as a method for individuals to reconvene at sleeping sites after nightly activity (Wiens & Zitzmann 2003b).

LISTEN TO VOCALIZATIONS

• Slow loris chitter  (Dr Anna Nekaris’ little fire face project; mp3)
• Slow loris chitter and scream  (Dr Anna Nekaris’ little fire face project; mp3)
• Slow loris panting  (Dr Anna Nekaris’ little fire face project; mp3)
• Slow loris scream  (Dr Anna Nekaris’ little fire face project; mp3)
• Slow Loris Vocalizations  (Dr Anna Nekaris’ little fire face project)

Slow lorises have a gland on their elbows that exude oils used in communication, of which the composition is particular to each species (Hagey et al. 2007). This secretion from the elbow glands probably evolved for communication, but can be toxic to humans if bitten, as licking is one mode for deposition of the scent. This is especially true among people who have had contact with the animals and may have developed allergies to them. Individuals have gone into shock and even died after slow loris bites (Wilde 1972; Hagey et al. 2007).

Olfactory communication is important in slow lorises, and they signal conspecifics by urine marking, and through deposition of scent from glands on their elbows and anus (Tenaza & Fitch 1984; Rasmussen 1986; Hagey et al. 2007). Rhythmic uriniation is one method of scent deposition in the species, in which the animal moves about and deposits urine as it moves (Rassmussen 1986). Facial rubbing on a substrate usually occurs in response to the scent of another slow loris (Rassmussen 1986). Olfactory communication is important in reproduction in slow lorises (Fisher et al. 2003a). N. pygmaeus males overmark the scent-marks of other males. N. pygmaeus urine-marking odor is individually distinguishable among the species, and females use marking and countermarks by males to assess the desirability of the males (Fisher et al. 2003a). Further, in captive experiments, females prefer males whose odor they are familiar with (Fisher et al. 2003b).

Postural and facial communication is not particularly common in slow lorises. However, two commonly seen postures/facial expressions are the grin and bare-teeth displays, both usually accompanied by vocalizations. Grins are shown by infants, usually when stressed. Bare-teeth displays involve showing the teeth, and are seen during agonism, but also during play behaviors (Rassmussen 1986).

Content last modified: March 18, 2009

Written by Kurt Gron. Reviewed by Helena Fitch-Snyder.

Cite this page as:
Gron KJ. 2009 March 18. Primate Factsheets: Slow loris (Nycticebus) Behavior . . Accessed 2020 July 10.

INTERNATIONAL STATUS

For individual primate species conservation status, please search the IUCN Red List.
Also search the current scientific literature for primate conservation status (overall as well as for individual species), and visit CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora).

Conservation information last updated in 2009 follows, for comparison:

CONSERVATION THREATS

Threat: Human-Induced Habitat Loss and Degradation

Slow lorises are also particularly susceptible to habitat fragmentation and the felling of feed and sleeping trees causes habitat degradation and increased contact with people (Choudhury 2001; Medhi et al. 2004). In India, for example, habitat destruction is the worst threat to slow lorises (Choudhury 1992). Jhum cultivation (slash-and-burn cultivation) is also a significant habitat threat in India, as is tea cultivation and other agricultural land use (Choudhury 1992; Medhi et al. 2004). Often human settlements follow these types of land use, inhibiting secondary growth (Medhi et al. 2004). Other reasons for habitat descrution include monoculture, logging, fuel-wood extraction, land use for paper production, and the construction of infrastructure (Choudhury 1992). In China, habitat destruction is also the biggest threat to resident slow lorises and suitable areas are often destroyed for cash crops such as rubber, sugarcane, and coffee growing (Lan 1999).

Threat: Invasive Alien Species

Due to importation of slow lorises from some areas of their range to others, sometimes non-local species of slow loris (that are not properly identified) are introduced or released if confiscated into habitats in which they are not native, potentially altering the ecology of native species of slow loris (Schulze & Groves 2004).

Threat: Harvesting (hunting/gathering)

Over large areas of their range, slow lorises are collected as pets and for illegal folk medicine. They are one of the most commonly traded protected primates in southeast Asia (Schulze & Groves 2004; Nekaris & Jaffe 2007). In some areas, they are also hunted for meat (Radhakrishna et al. 2006). However, due to their diminutive size, N. pygmaeus are not hunted intensely, but they are probably still sold in markets in Vietnam and even exported (Duckworth 1994; Fitch-Snyder & Thanh 2002). Animals are often exported from their countries of origin for medicinal uses and very often end up in China, but illegal export to Taiwan has also been recorded (Phipps 1992; Fitch-Snyder & Thanh 2002). Even if the lorises are not desired locally, they are often collected in neighboring areas and imported (Schulze & Groves 2004). In China, slow lorises are eaten, the bones are used for medicinal uses, and the fur for local hunting bags (Lan 1999). The illegal trade in the species is further evidenced by slow lorises being found for sale in Indonesian and Cambodian markets. In some areas, the trade is so intense that devoted animal rescue centers are overwhelmed (Malone et al. 2002; Streicher et al. 2002; Nekaris & Jaffe 2007). In Vietnam, collection for medicinal purposes results in captured animals being dried or placed in rice wine (Streicher et al. 2002). Some groups across the broad slow loris range believe that the collection of a loris eyeball may help the person’s eyesight (Medhi et al. 2004). Adding to the threat of their removal from their habitats, slow lorises very often die from the stress of being held captive (Streicher 2004).

Threat: Accidental Mortality

While trying to cross roads, slow lorises are sometimes hit and killed by automobile traffic (Radhakrishna et al. 2006).

Threat: Human Disturbance

In some protected areas of India, armed insurgent groups are present. Such groups may hunt slow lorises, but also discourage the patrols of forest guards, and thus reduce protection afforded to slow lorises (Radhakrishna et al. 2006). Further, recent wars in Indochina have significantly altered or destroyed slow loris habitats (Lan 1999).

LINKS TO MORE ABOUT CONSERVATION

CONSERVATION INFORMATION

• Conservation Database for Lorises and Pottos
• Dr Anna Nekaris’ little fire face project  (Saving the slow loris via ecology, education & empowerment)
• Husbandry Manual for Asian Lorisines (Nycticebus & Loris ssp.)  (loris-conservation.org)
• Links for all species

CONSERVATION NEWS

• Strange endangered primates you may have never heard of  (BBC; January 25, 2012)
• Animal picture of the day: radio collaring a slow loris  (Mongabay; July 17, 2011)
• 70 percent of Indonesia’s primates in danger of extinction  (BNO News; June 7, 2011)
• Slow loris YouTube videos fuel endangered species trade  (The Telegraph; March 22, 2011)
• The loris: Another primate at risk from traditional Asian medicine  (Scientific American; May 27, 2010)
• YouTube videos may be imperiling cuddly primate  (Mongabay; February 24, 2009)
• Cuddly primate trade banned  (Mongabay; June 11, 2007)
• Too cute for comfort  (BBC News; June 7, 2007)
• Slow Lorises Smuggler Eludes Arrest In Thailand  (Playfuls.com; March 1, 2007)
• Links for all species

ORGANIZATIONS INVOLVED IN Nycticebus CONSERVATION

• LVDI International
• Orangutan Tropical Peatland Project
• Community Conservation
• Israeli Primate Sanctuary
• Monkeyland Primate Sanctuary
• Rimrock Ranch Wildlife Conservancy, Ltd.
• Wildlife Friends Foundation Thailand

Content last modified: March 18, 2009

Written by Kurt Gron. Reviewed by Helena Fitch-Snyder.

Cite this page as:
Gron KJ. 2009 March 18. Primate Factsheets: Slow loris (Nycticebus) Conservation . . Accessed 2020 July 10.

The following references were used in the writing of this factsheet. To find current references for Nycticebus, search PrimateLit.

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Content last modified: March 18, 2009

IMAGES

	Nycticebus coucang Photo: Andrew Johns
	Nycticebus coucang Photo: J. R. Mackinnon
	Nycticebus coucang Photo: Marilyn Cole
	Nycticebus coucang Photo: Marilyn Cole