Animal Diversity Web

Ge­o­graphic Range

Loris tardi­gradus (the slen­der loris) is a strep­sirhine pri­mate re­stricted to the is­land of Sri Lanka. (Camp­bell, et al., 2011; Phillips, 1980; Schulze and Meier, 1995a)

• Biogeographic Regions
• oriental
  • native

• Other Geographic Terms
• island endemic

Habi­tat

Three sub­species of L. tardi­gradus and one sub­species of its only con­gener, Loris ly­dekke­ri­anus, main­tain fairly dis­crete habi­tat niches in Sri Lanka. Loris tardi­gradus tardi­gradus is found in wet, low­land forests of the south­west. Loris tardi­gradus gran­dis oc­cu­pies the cen­tral hills rang­ing from 731 m to 1036 m in el­e­va­tion and is thought to in­ter­breed with L. t. tardi­gradus at mid­dle el­e­va­tions in the ex­treme west of its range. Loris tardi­gradus nyc­tice­boides is a rare mon­tane form known only from its type lo­cal­ity in mist forests of the Hor­ton Plains at el­e­va­tions of greater than 1500 m. A sub­species of gray slen­der loris, Loris ly­dekke­ri­anus nordi­cus, in­hab­its the low­land dry forests and scrub jun­gle of the north. Some au­thors con­sider gran­dis and nyc­tice­boides to be sub­species of Loris ly­dekke­ri­anus (see Groves, 1998). This ac­count fol­lows the tax­o­nomic ac­count in Camp­bell et al. (2011). (Camp­bell, et al., 2011; Groves, 1998; Phillips, 1980; Schulze and Meier, 1995a)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• forest
• rainforest

• Range elevation

  0 to 2134 m

  0.00 to 7001.31 ft

Phys­i­cal De­scrip­tion

Loris tardi­gradus is a small (127 g - 256 g) pri­mate with long, gracile limbs, a slen­der body, and no tail. Its face is char­ac­ter­ized by promi­nent ears, a short ros­trum, and large, for­ward-ori­ented eyes with hazel-brown irises. Dis­tinc­tive patches of dark fur sur­round the eyes, and a white stripe runs from fore­head to nose. The col­oration of cir­cu­m­oc­u­lar patches and the shape of the in­te­roc­u­lar stripe are used to dis­tin­guish sub­species. The ros­trum is sharply pointed and ends in a moist, naked rhi­nar­ium. Slen­der loris ears (both L. tardi­gradus and L. ly­dekke­ri­anus), are longer than those of slow lorises (genus Nyc­tice­bus), and the mar­gins of the ears are usu­ally hair­less. Fe­males have two pairs of mam­mae which are naked dur­ing lac­ta­tion and cov­ered with fur at all other times. Limbs are sube­qual as the legs are bulkier and slightly longer than the arms. The palms of the hands and the soles of the feet are usu­ally naked. As in other strep­sirhine pri­mates, there is a toi­let-claw on the sec­ond digit of both feet. Their hands are smaller than their feet, and the index fin­ger is re­duced. Dig­its close syn­chro­nously, with the hal­lux and pollex op­pos­able to dig­its two through five. Like Nyc­tice­bus, and in con­trast to Per­o­d­icti­cus, Loris species have a hair­less brachial gland on the in­side of the arms. This gland pro­duces an ex­u­date im­por­tant in ol­fac­tory com­mu­ni­ca­tion, which may also have an anti-preda­tor func­tion. The basal meta­bolic rate of Loris tardi­gradus is not known, but lorises in gen­eral have slower me­tab­o­lisms than would be ex­pected from their body size. Re­search in­di­cates a BMR of 0.38 (ml O2/g * hr) for their close rel­a­tive, L. ly­dekke­ri­anus mal­abar­i­cus. (Al­ter­man, 1995; Camp­bell, et al., 2011; Hagey, et al., 2007; Izard and Ras­mussen, 1998; Mac­don­ald, 2001; McNab, 1984; Müller, et al., 1985; Napier and Napier, 1967; Nekaris and Stevens, 2007; Nowak, 1999; Phillips, 1980; Schulze and Meier, 1995a; Schulze and Meier, 1995b)

Three sub­species of L. tardi­gradus are rec­og­nized and can be dis­tin­guished by size and pelage char­ac­ter­is­tics. Loris tardi­gradus tardi­gradus is the small­est slen­der loris, weigh­ing from 128 g to 142 g and with a head-body length not ex­ceed­ing 206 mm. Dor­sal pelage is red to red­dish-brown, dark­est on the shoul­ders and paler on the lower back and pelvis. The fur of the lower back may be slightly frosted, but less so than Loris tardi­gradus gran­dis. A dark-col­ored dor­sal stripe is some­times pre­sent, but never as con­spic­u­ous as that of Loris ly­dekke­ri­anus nordi­cus. Ven­tral fur is yel­low­ish. Patches around the eyes are chest­nut col­ored, and the in­te­roc­u­lar stripe rarely bi­fur­cates above the eyes. Fe­males are larger than males and have a brown color, with lit­tle or no red. In­fants are gray dor­sally and white ven­trally. Subadult males have fe­male-like col­oration and grad­u­ally be­come more red. Loris tardi­gradus gran­dis is larger than L. t. tardi­gradus, has a less del­i­cate ap­pear­ance, and is more heav­ily furred, es­pe­cially on the limbs. It weighs up to 227 g and has a head-body length be­tween 209 mm and 256 mm. Dor­sal fur is gray and ven­tral fur is white. Frost­ing is much more pro­nounced than in L. t. tardi­gradus. The cir­cu­m­oc­u­lar patches are black or dark brown, and the in­te­roc­u­lar stripe bi­fur­cates and merges into white fur sur­round­ing the ears. Fe­males are big­ger, darker, and more frosted than males. Ju­ve­niles are brown and do not have frost­ing. Loris tardi­gradus nyc­tice­boides is known only from a few spec­i­mens. Its mean weight is 140 g, and its head-body length ranges from 204 mm - 213 mm. The fur is con­sid­er­ably longer than that of the other sub­species, with ven­tral hairs as long as 30 mm. Dor­sal pelage is brown and the ven­tral pelage is buff. Patches around the eyes are black, and the nar­row in­te­roc­u­lar stripe bi­fur­cates and con­tin­ues around the eye patches. This sub­species is unique in that the ears are com­pletely furred. The hands and feet are also no­tably hairier than those of the other sub­species. (Phillips, 1980; Schulze and Meier, 1995a)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• female larger
• sexes colored or patterned differently

• Range mass

  127 to 227 g

  4.48 to 8.00 oz

• Range length

  185 to 256 mm

  7.28 to 10.08 in

• Average basal metabolic rate

  0.714 W

  AnAge

Re­pro­duc­tion

Lit­tle is known of the mat­ing habits of Loris tardi­gradus in the wild. A num­ber of be­hav­iors de­scribed in L. ly­dekke­ri­anus have not been con­firmed in L. tardi­gradus, and much of the avail­able data (for ei­ther taxon) comes from cap­tive in­di­vid­u­als. Both species are re­ported to form so­cial as­so­ci­a­tions in which the larger home ranges of one or more males over­lap the smaller range of a sin­gle fe­male. Loris tardi­gradus tardi­gradus has been ob­served to gather in semi-sta­ble sleep­ing groups of one fe­male, her off­spring, and a sin­gle male; groups with mul­ti­ple males are re­ported for L. ly­dekke­ri­anus. In both taxa, the pres­ence of a post-cop­u­la­tion vagi­nal plug of hard­ened semen has been re­ported. This, along with elab­o­rate pe­nile mor­phol­ogy, has been taken as ev­i­dence of sperm com­pe­ti­tion and a multi-male breed­ing sys­tem. Nekaris (2003) ob­served sev­eral wild male L. ly­dekke­ri­anus ro­tat­ing among three es­trus fe­males, with each male sep­a­rately groom­ing each fe­male at dif­fer­ent times over the course of a sin­gle night. Nekaris (2003) pro­poses a multi-male, multi-fe­male (i.e., promis­cu­ous) mat­ing sys­tem. (Camp­bell, et al., 2011; Dix­son, 1995; Izard and Ras­mussen, 1985; Mac­don­ald, 2001; Napier and Napier, 1967; Nekaris, 2003; Nowak, 1999; Schulze and Meier, 1995b)

Ob­ser­va­tions of cap­tive Loris ly­dekke­ri­anus pop­u­la­tions in­di­cate no re­pro­duc­tive sea­son­al­ity, but this may not be true in the wild. It has been sug­gested that Loris tardi­gradus breed bian­nu­ally, peak birth times for L. ly­dekke­ri­anus in India occur dur­ing April and May and from Oc­to­ber to De­cem­ber. May-De­cem­ber birthing sched­ules have been re­ported in Sri Lanka as well. Short-term field stud­ies found no ev­i­dence for sea­son­al­ity in wild pop­u­la­tions of ei­ther Loris spe­ices and doc­u­mented one in­stance of a fe­male L. ly­dekke­ri­anus in es­trus while her close neigh­bors car­ried in­fants. Testis of both taxa switch fre­quently be­tween the scro­tal and in­guinal (i.e., de­scended and un­de­scended) con­di­tions, and no pat­tern of male gen­i­tal change has been dis­cov­ered with re­spect to fe­male es­trus or time-of-year. En­large­ment of male gen­i­tals ap­pears to be af­fected by am­bi­ent tem­per­a­ture rather than sex­ual ac­tiv­ity, with en­large­ment oc­cur­ring dur­ing in­creased tem­per­a­tures. (Camp­bell, et al., 2011; Izard and Ras­mussen, 1985; Nekaris, 2003; Nowak, 1999; Schulze and Meier, 1995b)

Courtship by male Loris tardi­gradus con­sists of a lengthy pur­suit of the fe­male, with threat vo­cal­iza­tions and ap­pease­ment vo­cal­iza­tions. It is not clear which role, threat­ener or ap­peaser, each gen­der as­sumes. Re­searchers have been un­able to ob­serve the en­tire courtship process, and no cop­u­la­tions have been wit­nessed. Mat­ing be­hav­ior in L. tardi­gradus ap­pears to be sim­i­lar to that in L. ly­dekke­ri­anus nordi­cus, which can last for five hours and is char­ac­ter­ized by ap­pease­ment vo­cal­iza­tions and ex­cited branch-shak­ing on the part of the male, and threat vo­cal­iza­tions by the fe­male. In cap­tive L. ly­dekke­ri­anus, when the fe­male is ready for cop­u­la­tion she com­mu­ni­cates her ac­cep­tance by adopt­ing a sus­pen­sory pos­ture (i.e., hang­ing quadrupedally on the un­der­side of a branch). In­tro­mis­sion lasts from two to six­teen min­utes and is con­cluded by a threat vo­cal­iza­tion from the fe­male. Both gen­ders lick their gen­i­tals after cop­u­la­tion. A sin­gle cop­u­la­tion of L. ly­dekke­ri­anus has been doc­u­mented in the wild, which was pre­ceded by an hour-long courtship pur­suit and oc­curred in a sus­pen­sory po­si­tion under a hor­i­zon­tal branch. Males in other trees ha­rassed the mat­ing pair, and cop­u­la­tion was twice in­ter­rupted while the focal male chased away his ri­vals. (Camp­bell, et al., 2011; Izard and Ras­mussen, 1985; Nekaris, 2003; Nowak, 1999; Schulze and Meier, 1995b)

Ges­ta­tion in Loris tardi­gradus lasts 166 to 175 days, and fe­males give birth to a max­i­mum of two lit­ters per year that usu­ally con­sists of sin­gle off­spring. Oc­ca­sion­ally, a fe­male may give birth to twins. Fe­males are known to reen­ter es­trus while nurs­ing a pre­vi­ous lit­ter. In­fants are al­tri­cial, cling­ing to their moth­ers con­tin­u­ously for the first four weeks of life. After four weeks, young are placed in a shel­tered lo­ca­tion dur­ing ac­tive night­time pe­ri­ods. Wean­ing takes place around 185 days, by which time the ju­ve­niles have achieved adult size. (Camp­bell, et al., 2011; Izard and Ras­mussen, 1985; Nekaris, 2003; Nowak, 1999; Schulze and Meier, 1995b)

• Key Reproductive Features
• iteroparous
• year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous

• Breeding interval

  Loris tardigradus breeds twice a year

• Breeding season

  None confirmed

• Range number of offspring

  1 to 2

• Average number of offspring

  1.3

  AnAge

• Range gestation period

  167 to 174 days

• Average weaning age

  185 days

• Average age at sexual or reproductive maturity (female)
  Sex: female

  380 days

  AnAge

• Average age at sexual or reproductive maturity (male)
  Sex: male

  365 days

  AnAge

Lit­tle in­for­ma­tion ex­ists con­cern­ing re­pro­duc­tion in slen­der lorises. The en­tire process, from cop­u­la­tion to in­de­pen­dence of off­spring, takes at least 320 days, and fe­males may be­come preg­nant with a new lit­ter be­fore wean­ing pre­vi­ous young. Phys­i­o­log­i­cal costs of lac­ta­tion are high, as fe­males pro­duce milk with un­usu­ally high fat and pro­tein con­tent com­pared to that of other strep­sirhine pri­mates. Sex­u­ally ma­ture fe­males make a sub­stan­tial caloric in­vest­ment in re­pro­duc­tion through­out the year, but more re­search is needed to quan­tify this in­vest­ment and to ex­plore its im­pli­ca­tions for feed­ing ecol­ogy, so­cial sys­tems, and pat­terns of parental care. (Camp­bell, et al., 2011; Izard and Ras­mussen, 1985; Izard and Ras­mussen, 1998; Nekaris, 2003; Schulze and Meier, 1995b; Tilden and Of­tedal, 1997)

At birth, Loris tardi­gradus in­fants are help­less. They in­stinc­tively cling to their mother's fur and re­main there day-and-night for at least four weeks. After four weeks, lorises "park" their young in dense tan­gles of branches dur­ing night­time for­ag­ing ac­tiv­ity. Re­search in­di­cates that L. ly­dekke­ri­anus, a close rel­a­tive of L. tardi­gradus, moth­ers aban­doned their off­spring for the en­tire night, and that parked in­fants were some­times played-with and groomed by males. Al­though the re­la­tion­ship of males to in­fants is un­known, in­di­vid­u­als who babysat in this way be­longed to the same sleep­ing group as the mother. This be­hav­ior is prob­a­bly a form of af­fil­ia­tive pa­ter­nal care. The as­sis­tance of males in night­time par­ent­ing may give lac­tat­ing moth­ers in­creased mo­bil­ity when for­ag­ing, help­ing them to sat­isfy their high caloric ex­penses. In con­trast, L. tardi­gradus in­fants are not vis­ited by males, and fe­males re­turned to parked young as fre­quently as once per hour dur­ing the night. (Camp­bell, et al., 2011; Izard and Ras­mussen, 1985; Izard and Ras­mussen, 1998; Nekaris, 2003; Schulze and Meier, 1995b; Tilden and Of­tedal, 1997)

Rare cases of in­fan­ti­cide have been re­ported for cap­tive Loris tardi­gradus. Such in­stances are al­ways said to be ac­com­pa­nied by "en­vi­ron­men­tal stress", and do not ap­pear to be di­rected by males to­ward the off­spring of other males. There are no re­ports of in­fan­ti­cide in wild pop­u­la­tions of L. tardi­gradus. (Camp­bell, et al., 2011; Izard and Ras­mussen, 1985; Izard and Ras­mussen, 1998; Nekaris, 2003; Schulze and Meier, 1995b; Tilden and Of­tedal, 1997)

• Parental Investment
• altricial
• female parental care
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
• post-independence association with parents
• extended period of juvenile learning

Lifes­pan/Longevity

There is no in­for­ma­tion avail­able on the longevity of Loris tardi­gradus in the wild. One cap­tive in­di­vid­ual re­port­edly lived 15.5 years. (Nowak, 1999)

• Range lifespan
  Status: captivity

  15.5 (high) years

• Average lifespan
  Status: captivity

  12.4 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Sex: male
  Status: captivity

  16.4 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Sex: male
  Status: captivity

  14.0 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Status: captivity

  15.0 years

  Max Planck Institute for Demographic Research

Be­hav­ior

Slen­der lorises are noc­tur­nal and ar­bo­real. Their move­ments are fa­mously slow, fluid, and noise­less. Tests on cap­tive an­i­mals in­di­cate nor­mal speeds of about 0.59 m/sec. Lorises are, how­ever, ca­pa­ble of rapid climb­ing and noisy episodes of branch-shak­ing. A re­cent field study by Nekaris and Stevens (2007) found "rapid quadrupedal­ism" to be sur­pris­ingly com­mon in slen­der lorises. This scram­bling mode of lo­co­mo­tion is qual­i­ta­tively dif­fer­ent from hand-over-hand climb­ing, and is used about 26% of the time. Dur­ing this form of move­ment, in­di­vid­u­als reach speeds ap­proach­ing 1.2 m/s. Slen­der lorises may be ca­pa­ble of "mini leaps", but they usu­ally move from tree to tree by care­ful can­tilever­ing, which in­volves grasp­ing a ver­ti­cal branch with their hindlimbs and ex­tend­ing its body hor­i­zon­tally across the gap. Hip, ankle, and wrist joints are very mo­bile (Napier & Napier, 1967), and pre­car­i­ous pos­tures can be main­tained for ex­tended pe­ri­ods be­cause retia mirabilia sup­ply the limb mus­cles with oxy­gen and re­move cel­lu­lar waste, pre­vent­ing cramp­ing. Lorises typ­i­cally travel on the tops of branches, and they pre­fer climb­ing struc­tures (e.g., branches or vines) small enough to be grasped in their hands. In­di­vid­u­als in a cap­tive grey slen­der loris colony showed ex­treme care when ne­go­ti­at­ing smooth ver­ti­cal trunks 10 cm in di­am­e­ter. In the same colony, bipedal stand­ing to the tops of branches and bipedal hang­ing by the hindlimbs un­der­neath branches were both re­peat­edly ob­served, how­ever, bipedal hang­ing by the fore­limbs was rare. (Camp­bell, et al., 2011; Napier and Napier, 1967; Nekaris and Stevens, 2007; Nowak, 1999; Phillips, 1980; Schulze and Meier, 1995b)

Dur­ing the day, slen­der lorises ag­gre­gate in sleep­ing groups which in­clude a sin­gle adult fe­male, her off­spring, and one or more males. These as­so­ci­a­tions may be sta­ble from night to night, and adult males in a sleep­ing group may par­tic­i­pate in parental care. Both in cap­tiv­ity and in the wild, slen­der lorises par­tic­i­pate in so­cial co­he­sion be­hav­iors such as hud­dling, al­logroom­ing, play-wrestling and play-bit­ing. A va­ri­ety of vo­cal­iza­tions, in ad­di­tion to body lan­guage and elab­o­rate ol­fac­tory com­mu­ni­ca­tion are uti­lized. In cap­tiv­ity, grey slen­der lorises openly steel food from each other with­out pro­vok­ing hos­til­ity. Al­though ag­gres­sion cap­tive pop­u­la­tions is not un­com­mon, most ag­gres­sive be­hav­ior in the wild has been de­scribed be­tween un­re­lated adult fe­males and be­tween males who do not be­long to the same sleep­ing group. Night­time ac­tiv­i­ties re­ported for slen­der lorises con­sists pri­mar­ily of travel and for­ag­ing, but also in­cludes so­cial ac­tiv­i­ties, in­clud­ing those be­tween mother and young, and rest. (Camp­bell, et al., 2011; Nekaris, 2003; Schulze and Meier, 1995b)

• Key Behaviors
• arboreal
• scansorial
• nocturnal
• motile
• social

• Range territory size

  15,900 to 36,000 m^2

Home Range

Al­though no in­for­ma­tion is avail­able con­cern­ing home range in Loris tardi­gradus, av­er­age home range for L. ly­dekke­ri­anus males is 3.6 ha (36,000 m^2) and 1.59 ha (15,900 m^2) for fe­males. (Camp­bell, et al., 2011; Nekaris and Stevens, 2007)

Com­mu­ni­ca­tion and Per­cep­tion

There is no in­for­ma­tion avail­able re­gard­ing com­mu­ni­ca­tion and per­cep­tion in slen­der lorises.

Slen­der lorises call to one other through­out the night, and on sev­eral oc­ca­sions even di­rected vo­cal­iza­tions at po­ten­tial preda­tors. The known vocal reper­toire of slen­der lorises con­sists whis­tles, chit­ters, zic calls, krik calls, growls, and screams. Whis­tle in­di­cate ex­cite­ment and ag­gres­sion and con­sists of one to three dis­tinct syl­la­bles, each end­ing with a de­scend­ing fre­quency sweep. Uti­lized by males and fe­males, whis­tles are al­ways loud, and may be au­di­ble to hu­mans from 100 m away. Ev­i­dence sug­gests that whis­tles are most preva­lent in wild pop­u­la­tions, pos­si­bly be­cause long dis­tance com­mu­ni­ca­tions are un­nec­es­sary in cap­tiv­ity. In cap­tiv­ity, whistling in one cage pro­voked re­sponse vo­cal­iza­tions from groups caged nearby. Chit­ter are used as a de­fen­sive threat and are some­times as­so­ci­ated with star­ing or phys­i­cal shov­ing. Pri­mar­ily ut­tered by fe­males, chit­ters are often used in re­sponse to a courtship pur­suit by a male. Chit­ters con­sist of rapid clicks at fre­quen­cies up to 20 kHz. Zic calls con­sist of high fre­quency mono­syl­la­bles that are used by an in­fant to at­tract the at­ten­tion of its mother. Parked in­fants often zic-call, at which point the mother re­turns from for­ag­ing and col­lects the in­fant. Low in­ten­sity zic calls may be uti­lized when an in­fant dis­likes groom­ing, but high in­ten­sity calls sig­nify fear or pain. In cap­tiv­ity, adults other than the mother may com­fort a zic-call­ing in­fant. Krik calls are a hiss-like, low fre­quency sound used by males to ap­pease chit­ter­ing fe­males and are com­monly used by males as a pre­lude to al­logroom­ing. Fe­males use krick calls to ap­pease zic-call­ing in­fants. Some­times male-fe­male duets are per­formed using krik calls. Growl are an un­voiced threat vo­cal­iza­tion that are used against preda­tors, or by cap­tured an­i­mals. Rarely ut­tered in in­traspe­cific con­texts, growls are most often used in con­nec­tion with de­fen­sive body lan­guage. Screams are used in cir­cum­stances of pro­longed threat and are as­so­ci­ated with se­cre­tion of ex­u­date from the brachial gland. (Nekaris, 2003; Nekaris, et al., 2007; Schulze and Meier, 1995b)

Like many mam­mals and most noc­tur­nal pri­mates, slen­der lorises make ex­ten­sive use of scent mark­ings to com­mu­ni­cate in­for­ma­tion. Urine mark­ing are made by rhyth­mic mic­turi­tion (a stereo­typed be­hav­ior in which the an­i­mal trav­els along a branch and de­posits urine at in­ter­vals by rhyth­mi­cally low­er­ing its gen­i­tals to the sub­strate), anogen­i­tal drag­ging, and in­di­rect ap­pli­ca­tion (urine ap­plied to the sub­strate via the hands or feet of the uri­nat­ing in­di­vid­ual). Self-wash­ing with urine is reg­u­larly ob­served in a va­ri­ety of con­texts, in­clud­ing be­fore groom­ing in­fants prior to nightly park­ing, when prepar­ing to catch nox­ious in­sects, prior to con­sum­ing nox­ious prey items, and in re­sponse to being stung by them. Urine mark­ing is rarely ob­served in the vicin­ity of trees used for sleep­ing, but marks at lo­cal­i­ties within the range-over­lap area shared by sleep­ing-group mem­bers were ea­gerly re­ceived and coun­ter­marked. Scent com­mu­ni­ca­tion also plays a role in im­me­di­ate so­cial be­hav­ior. Anogen­ti­cal sniff­ing (male to fe­male) often pre­cedes groom­ing, and groom­ing bouts fre­quently in­volve rub­bing and lick­ing of the brachial gland. (Al­ter­man, 1995; Nekaris and Stevens, 2007; Schulze and Meier, 1995b)

Slen­der lorises use a va­ri­ety of com­mu­nica­tive pos­tures, ac­tions, and fa­cial ex­pres­sions in­di­cat­ing ag­gres­sion, sub­mis­sion, con­tent­ment, fear, sex­ual in­ten­tion (male), sex­ual readi­ness (fe­male), and other kinds of so­cially rel­e­vant in­for­ma­tion. Through al­logroom­ing and hud­dling, touch plays an im­por­tant role in es­tab­lish­ing and main­tain­ing group co­he­sion. It may also help ori­ent them in the dark. (Schulze and Meier, 1995b)

• Communication Channels
• visual
• tactile
• acoustic
• chemical

• Other Communication Modes
• duets
• pheromones
• scent marks

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Slen­der lorises are pri­mar­ily in­sec­tiv­o­rous, spe­cial­iz­ing to some ex­tent on toxic and un­sa­vory species. Par­tic­u­larly nox­ious in­sects are eaten with ev­i­dent dis­taste, and in­sects which spray ir­ri­tant chem­i­cals are re­moved from their colonies and eaten some dis­tance away, while the loris sali­vates gra­tu­itously, shakes its head, and shuts its eyes. Ev­i­dence sug­gests that volatile chem­i­cals in­gested with in­sect food might be reused by lorises as a kind of ol­fac­tory cam­ou­flage. For­ag­ing lorises are fre­quently ob­served wash them­selves in urine be­fore ap­proach­ing toxic in­sects, per­haps in order to mask their own scent. The hunt­ing style of slen­der lorises and other lorises is to ap­proach silently and cau­tiously, then to make a sud­den ex­plo­sive grab with one or both hands. Pre­da­tion be­hav­ior of slen­der lorises has been de­scribed as a fixed ac­tion pat­tern that be­gins with vi­sual fix­a­tion of the prey, fol­lowed by lay­ing back of the loris' ears, and con­clud­ing with the grasp­ing mo­tion, which is al­ways com­pleted re­gard­less of whether or not the prey item is re­moved. In the wild, nearly 100% of the diet is pro­teina­ceous and in­cludes in­sects, tree frogs, geckos, small birds and eggs. They may oc­ca­sion­ally for­age on fruit when avail­able. In cap­tiv­ity, slen­der lorises are fed green sal­ads and plan­tains, and read­ily con­sume mice. (Camp­bell, et al., 2011; Mac­don­ald, 2001; Napier and Napier, 1967; Nekaris and Stevens, 2007; Nekaris, et al., 2007; Nowak, 1999; Phillips, 1980; Schulze and Meier, 1995b)

• Primary Diet
• carnivore
  • insectivore

• Animal Foods
• birds
• mammals
• amphibians
• reptiles
• eggs
• insects

• Plant Foods
• leaves
• fruit
• flowers

Pre­da­tion

There are few known preda­tors of Loris tardi­gradus. They may oc­ca­sion­ally be op­por­tunis­ti­cally taken by mam­malian car­ni­vores in­clud­ing fe­lids and rap­tors. It has been re­ported that genets and civets prey on lorises, but in sev­eral in­ter­ac­tions ob­served by re­searchers be­tween lorises and civets (Viver­ric­ula in­dica ma­jori, Para­dox­u­rus zey­lo­nen­sis) or cats (Felis viver­ri­nas), lorises sim­ply whis­tled until the po­ten­tial preda­tor moved away. It is not clear if the whis­tle func­tions as a warn­ing to con­specifics, or as a pur­suit de­ter­rence sig­nal to the preda­tor. Loris tardi­gradus fe­males and their in­fants react with alarm to the pres­ence of ven­omous com­mon kraits and moved to a shel­tered lo­ca­tion until the snake has passed. When cap­tured by re­searchers, lorises per­form a de­fen­sive be­hav­ior which re­sem­bles that of in­dian co­bras, which are pre­sent through­out the ge­o­graphic range of L. tardi­gradus. When cap­tured, L. tardi­gradus raises its arms above its head and sways its slen­der body side to side. (Al­ter­man, 1995; Hagey, et al., 2007; Krane, et al., 2003; Schulze and Meier, 1995b)

The brachial glands of slow lorises (Nyc­tice­bus) se­crete volatile chem­i­cals which can be toxic to hu­mans. It is not clear whether these com­pounds func­tion as a poi­son or an alarm pheromone, but se­cre­tion of a pun­gent-smelling ex­u­date from the brachial gland is a com­mon re­sult of fear in both slow and slen­der lorises. Al­ter­man (1995) hy­poth­e­sized that volatiles in the brachial gland do not be­come ac­tive until they are mixed with saliva, and per­formed pre­lim­i­nary tests sug­gest­ing that mam­malian car­ni­vores such as clouded leop­ards, bin­tur­ongs, and sun bears re­spond with ex­treme aver­sion to brachial gland ex­u­date when it is mixed with loris saliva, but not when it is pre­sented alone. Other re­searchers iden­ti­fied pro­teins in the brachial ex­u­date with re­gions of 70% se­quence sim­i­lar­ity to a known felid al­ler­gen. No stud­ies have in­ves­ti­gated the com­po­si­tion or func­tion of brachial gland ex­u­date in slen­der lorises, but L. tardi­gradus may be pro­tected from pre­da­tion by virtue of un­palata­bil­ity. (Al­ter­man, 1995; Hagey, et al., 2007; Krane, et al., 2003; Schulze and Meier, 1995b)

• Anti-predator Adaptations
• mimic

Ecosys­tem Roles

There is no in­for­ma­tion avail­able re­gard­ing the eco­log­i­cal role of slen­der lorises. They prey heav­ily on in­sects, but they are not com­mon any­where and it is doubt­ful that they con­trol pop­u­la­tions.

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Slen­der lorises are il­le­gally hunted ex­ploited for tra­di­tional med­i­cine and for the pet trade. (Nekaris, 2010)

• Positive Impacts
• pet trade
• body parts are source of valuable material

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Loris bites may in­duce shock in hu­mans and are often slow to heal. How­ever, wild lorises are ex­tremely shy of con­tact and do not at­tack hu­mans un­less pro­voked. No other ad­verse ef­fects of Loris tardi­gradus on hu­mans are known. (Al­ter­man, 1995)

• Negative Impacts
• injures humans
  • bites or stings

Con­ser­va­tion Sta­tus

Loris tardi­gradus is con­sid­ered en­dan­gered by the IUCN's Red List of Threat­ened Species and is listed under Ap­pen­dix II under the Con­ven­tion on In­ter­na­tional Trade in En­dan­gered Species of Wild Fauna and Flora. Major threats to their per­sis­tence in­clude habi­tat loss, hunt­ing for the pet trade and for their meat, road kills, su­per­sti­tious kills, and tra­di­tional med­i­cine. In his Man­ual of Sri Lankan mam­mals, W.W.A. Phillips wrote that L. tardi­gradus, "is most dif­fi­cult to dis­cover un­less the jun­gle in which it lives is being felled." Habi­tat de­struc­tion is a se­ri­ous threat to all three L. tardi­gradus sub­species, and the sur­vival of the species de­pends on the en­force­ment of their pro­tec­tions through­out 7 dif­fer­ent na­ture pre­serves in Sri Lanka and the es­tab­lish­ment of cor­ri­dors be­tween pro­tected areas. ("Ap­pen­dices I, II, and III", 2010; Nekaris, 2010; Phillips, 1980)

• IUCN Red List

  Endangered
  More information

• IUCN Red List

  Endangered
  More information

• CITES

  Appendix II

Con­trib­u­tors

Rory McGuin­ness (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Phil Myers (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor, John Berini (ed­i­tor), An­i­mal Di­ver­sity Web Staff.

Ref­er­ences

2010. "Ap­pen­dices I, II, and III" (On-line). Con­ven­tion on In­ter­na­tional Trade in En­dan­gered Species of Wild Fauna and Flora. Ac­cessed April 11, 2011 at http://​www.​cites.​org/​eng/​app/​appendices.​shtml.

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Camp­bell, C., A. Fuentes, K. MacK­in­non, S. Bearder, R. Stumpf. 2011. Pri­mates in Per­spec­tive. Ox­ford: Ox­ford Uni­ver­sity Press.

Dix­son, A. 1995. Sex­ual se­lec­tion and the evo­lu­tion of cop­u­la­tory be­hav­ior in noc­tur­nal prosimi­ans. Pp. 95-188 in L Al­ter­man, G Doyle, M Izard, eds. Crea­tures of the Dark: The Noc­tur­nal Prosimi­ans. New York: Plenum Press.

Groves, C. 1998. Sys­tem­at­ics of tar­siers and lorises. Pri­mates, 39/1: 13-27.

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Mac­don­ald, D. 2001. The New En­cy­clo­pe­dia of Mam­mals. Ox­ford: Ox­ford Uni­ver­sity Press.

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Müller, E., U. Ni­eschalk, B. Meier. 1985. Ther­moreg­u­la­tion in the slen­der loris (Loris tardi­gradus). Folia Pri­ma­to­log­ica, 44/3-4: 216-226.

Napier, J., P. Napier. 1967. A Hand­book of Liv­ing Pri­mates: Mor­phol­ogy, Ecol­ogy and Be­hav­ior of Non­hu­man Pri­mates. New York: Aca­d­e­mic Press.

Nekaris, A. 2010. "Loris tardi­gradus" (On-line). IUCN Red List of Threat­ened Species. Ac­cessed April 11, 2011 at http://​www.​iucnredlist.​org/​apps/​redlist/​details/​12375/​0.

Nekaris, K. 2001. Ac­tiv­ity bud­get and po­si­tional be­hav­ior of the Mysore slen­der loris (Loris tardi­gradus ly­dekke­ri­anus): im­pli­ca­tions for slow climb­ing lo­co­mo­tion. Folia Pri­ma­to­log­ica, 72/4: 228-241.

Nekaris, K. 2003. Ob­ser­va­tions of mat­ing, birthing, and parental be­hav­ior in three sub­species of slen­der loris (Loris tardi­gradus and Loris ly­dekke­ri­anus) in India and Sri Lanka. Folia Pri­ma­to­log­ica, 74: 312-336.

Nekaris, K., E. Pim­ley, K. Ablard. 2007. Preda­tor de­fense by slen­der lorises and pot­tos. Pp. 222-240 in S Gursky, K Nekaris, eds. Pri­mate Anti-Preda­tor Strate­gies (De­vel­op­ments in Pri­ma­tol­ogy: Progress and Prospects). New York: Springer US.

Nekaris, K., D. Ras­mussen. 2003. Diet and feed­ing be­hav­ior of Mysore slen­der lorises. In­ter­na­tional Jour­nal of Pri­ma­tol­ogy, 24/1: 33-46.

Nekaris, K., N. Stevens. 2007. Not all lorises are slow: rapid ar­bo­real lo­co­mo­tion in Loris tardi­gradus of south­west­ern Sri Lanka. Amer­i­can Jour­nal of Pri­ma­tol­ogy, 69/1: 112-120.

Nowak, R. 1999. Walker's Pri­mates of the World. Bal­ti­more: Johns Hop­kins Uni­ver­sity Press.

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Schulze, H., B. Meier. 1995. Be­hav­ior of cap­tive Loris tardi­gradus nordi­cus: a qual­i­ta­tive de­scrip­tion, in­clud­ing some in­for­ma­tion about mor­pho­log­i­cal bases of be­hav­ior. Pp. 221-250 in L Al­ter­man, G Doyle, M Izard, eds. Crea­tures of the Dark: The Noc­tur­nal Prosimi­ans. New York: Plenum Press.

Schulze, H., B. Meier. 1995. The sub­species of Loris tardi­gradus and their con­ser­va­tion sta­tus: a re­view. Pp. 193-210 in L Al­ter­man, G Doyle, M Izard, eds. Crea­tures of the Dark: The Noc­tur­nal Prosimi­ans. New York: Plenum Press.

Tilden, C., O. Of­tedal. 1997. Milk com­po­si­tion re­flects pat­terns of ma­ter­nal care in prosimian pri­mates. Amer­i­can Jour­nal of Pri­ma­tol­ogy, 41/3: 195-211.