Mother-infant interactions in captive slow lorises (Nycticebus coucang)

Information is presented about mother-infant interactions and infant development in a rarely studied prosimian primate, the slow loris (Nycticebus coucang). Four dyads were observed, by means of closed circuit TV, in a semi-natural environment for 1 hour per day three times a week. Infants were inactive for the first 6–8 weeks. Although mothers carried infants, they also left them alone for substantial periods of time after the 1st week. Over the 20-week study period, there was a significant decline in ventral contact but not in sitting within 12 inches or engaging in active social interactions. By the end of the study, infants were not yet fully independent. Three of the 4 were primarily responsible for maintaining physical closeness to the mother; they made most of the approaches and mothers made most of the departures. However, only 2 of the 4 infants had assumed responsibility for the initiation and maintenance of social interactions with the mother. By comparison with other nocturnal prosimians of similar size, the rate of development is relatively slow. Unlike many anthropoids, mothers were not strongly protective or rejecting. They did not bring infants back to a fixed location or try to prevent infants from leaving them; and the decline in ventral contact was not accompanied by fights between the pair. The 3 group-living mothers were more protective than the single individually housed mother, and it would seem advisable to isolate mother-infant pairs in laboratory breeding colonies.     

Mother-infant interactions in slow lorises (Nycticebus bengalensis) and pygmy lorises (Nycticebus pygmaeus)

The study had three purposes: (1) to obtain information about mother-infant interactions in a rarely studied nocturnal prosimian, the pygmy loris (Nycticebus pygmaeus); (2) to compare pygmy lorises with a closely related and better-studied nocturnal prosimian, the Bengal slow loris (Nycticebus bengalensis); and (3) to determine how the presence of a second offspring affected mother-infant interactions in pygmy lorises. Three Bengal slow loris mothers and 3 pygmy loris mothers served as subjects, along with their 10 offspring (4 Bengal slow loris singletons, 2 pygmy loris singletons and 2 sets of pygmy loris twins). Observations were carried out in a zoo research facility for the first 24 weeks of the infants' lives. Although the two species differ in size and reproductive patterns, mother-infant interactions were similar. The primary modes of infant and adult contact were ventral and passive contact, respectively. Mothers parked their infants from the first week, and infants followed from the second week. Mothers displayed little protection or rejection, and there was little aggression. Infants solicited play and social grooming from their mothers. Pygmy loris mothers engaged in social grooming and play with their infants more frequently and for longer periods if the infant was a singleton rather than a twin.     

Reproduction in the slow loris (Nycticebus coucang)

The reproductive biology of the slow loris (Nycticebus coucang) is poorly documented because of infrequent captive breeding success and the absence of field studies of this species. Reproductive data were collected from a breeding colony of slow lorises held at the Duke University Primate Center for the past 10 years. Nineteen infants were born, with a sex ratio of 1:1 and a neonatal mortality rate of 15.8%. In all cases, litter size was one. Females born in the colony copulated for the first time between 18 and 24 months of age. A male that reached sexual maturity in the colony sired his first offspring at the age of 17 months. Estrous cycles ranged in duration from 29–45 days, with copulations usually occurring for 1 day of estrus. Gestation length averaged 192.2 days. Although a postpartum estrus was observed in three cases of infant death, no conceptions resulted. Lactation lasted approximately 6 months. A clear birth peak was observed, with 12 out of 19 births occurring in March, April, and May. The comparatively low basal metabolic rate of this species may account for the unusually low reproductive rate of the slow loris in comparison with other prosimian primates.     

The subependyma of the primate, slow loris (Nycticebus coucang coucang)

The subependymal plate of the primate slow loris (Nycticebus coucang coucang) has been studied by electron microscopy. It is composed of a mixed population of several cell types in which the subependymal cells preponderate. Free subependymal cells are found in the ‘border area’ near the corpus callosum or the neuropile of the caudate nucleus. In common with the subependymal cells they show a scanty cytoplasm containing mostly free ribosomes. Typical neuroglial cells namely, microglia, astrocytes and oligodendrocytes are also identified in this region. Among the various cell types mentioned there are present also a few occasional cells which have features bearing a resemblance to the subependymal cell on the one hand and to the microglia on the other. The morphological evidence suggests that in parallel with the macroglia the microglia could be derived by stepwise transformation of the subependymal cells.     

Cranial allometry and geographic variation in slow lorises (Nycticebus)

A series of 20 craniodental measurements was obtained for two sister taxa: Nycticebus coucang (common slow loris) and N. pygmaeus (pygmy slow loris). Multivariate analysis of variance was performed with adult data to describe patterns of subspecific and specific variation in this genus. The geometric mean of adult cranial dimensions was compared to field data on latitudinal coordinates for available specimens to investigate if size variation in Nycticebus is clinal in nature. Ontogenetic series for larger-bodied N. coucang and smaller-bodied N. pygmaeus were compared to test the hypothesis that species and subspecific variation in skull form results from the differential extension of common patterns of relative growth. A MANOVA provides independent support of Groves's [pp. 44–53 in Proceedings of the Third International Congress on Primatology, Vol. 1 (Basel: S. Karger), 1971] classification of Nycticebus into two species, with four subspecies in the common slow loris and one form of the pygmy slow loris. Within N. coucang, cranial proportions for all four subspecies are ontogenetically scaled, and size differentiation is mainly clinal (Bergmann's Rule). N. c. bengalensis represents the most northerly disposed and the largest form. N. c. javanicus represents the next-largest form and is located in a southerly direction the next-farthest away from the equator. N. c. coucang and N. c. menagensis are both equatorial; however, the latter subspecies is the smallest. A genetic basis for some of the taxonomic variation between N. c. coucang and N. c. menagensis is supported by such nonclinal variation in body size. Variation in the presence/absence of I² is not size-related but rather tracks geographic proximity and isolating factors which predate the most recent inundation of the Sunda Shelf. Although they inhabit a nonequatorial environment, pygmy slow lorises are the smallest of all Nycticebus. As N. pygmaeus is sympatric with N. c. bengalensis, the largest slow loris, it appears that the evolution of its smaller body size represents a case of character displacement. Unlike N. coucang, skull size becomes significantly smaller in more northern N. pygmaeus. This may also reflect character displacement between sympatric sister taxa underlain by a cline-dependent ecological factor which is marked in more northerly latitudes. On the other hand, the negative correlation between body size and latitude in N. pygmaeus could be due to the influence of nonprimate fauna, such as predators, which themselves evince a similar clinal pattern. Analyses of relative growth indicate that skull proportions in the two species of Nycticebus are ontogenetically scaled in two-thirds of the cases. All but one of the seven comparisons (interorbital breadth) which do not indicate ontogenetic scaling represent part of the masticatory complex. This likely reflects a reorganization of N. pygmaeus maxillomandibular proportions linked to smaller size and changes in diet. Am. J. Primatol. 45:225–243, 1998. © 1998 Wiley-Liss, Inc.     

Neuroglia in the corpus callosum of the primate, slow loris (Nycticebus coucang coucang)

The corpus callosum of adult slow loris consists of a mixed population of several cell types, i.e. free subependymal cells, oligodendrocytes, astrocytes and microglia. The free subependymal cell is rather small and slender with a somewhat patchy nucleus. It shows scanty cytoplasm with free ribosomes. Oligodendrocytes vary both in nuclear and cytoplasmic densities and can be divided into three classes: light, medium dense and dark types. Their cytoplasm contains microtubules, rough endoplasmic reticulum and Golgi saccules. Astrocytes are pale cells with large amount of filaments in their cytoplasm. Microglia are small cells with granulated nuclei. The cells often show large cytoplasmic protrusions containing the usual cell organelles and lipofuscin bodies in their cytoplasm. Lastly, cells with typical features of neurons are occasionally encountered among the white matter.     

Welfare impacts of the illegal wildlife trade in a cohort of confiscated greater slow lorises,Nycticebus coucang

Illegal harvesting and trade are major forces behind population declines of wild slow lorises (genus Nycticebus). The impacts of the wildlife trade on individual slow lorises have not been as well described. In this article, we describe quantitatively the consequences of the wildlife trade for 77 greater slow lorises, N. coucang, who were confiscated en masse and brought to Cikananga Wildlife Center in Indonesia. Medical records indicated that in total, 28.6% of the slow lorises died within the first 6 months, mostly due to traumatic injury, and all the infants died. The greatest sources of morbidity were external wounds (33.1% of 166 total medical events) and dental problems (19.3%). Of the surviving individuals, 25.4% displayed abnormal behavior. Behavioral observations indicated that healthy adults (n = 3) spent 48.2% of their active period performing stereotypies. These data illustrate the physical and behavioral impacts of the illegal wildlife trade on the welfare of slow lorises. We suggest that sharing these individual stories may help generate empathy and educate the public about the impacts of the exotic companion-animal (pet) trade on nonhuman animal welfare.     

Excretion of radiolabeled estradiol metabolites in the slow loris (Nycticebus coucang)

The excretion pattern of estradiol was studied in the slow loris Nycticebus coucang) and the ring-tailed lemur (Lemur catta) in order to compare steroid excretion in two representative prosimian species. Daily urinary estrone conjugate measurements in the female loris provided little information when applied over prolonged periods. As a result of these negative data, a metabolic study was performed to determine if estrogen excretion patterns in the slow loris differed from those in the lemur, where urinary assays proved a useful tool in characterizing reproductive cycles. Radio-labeled estradiol was injected intravenously, and serial urine and fecal collections were analyzed for radiolabeled metabolites. The results of these studies demonstrate that more than 92% of the radiolabel was excreted in the feces of the loris, in contrast to only 16% excreted in the feces of the lemur.     

Activity changes with illumination in slow loris Nycticebus coucang

The relationship between illumination and levels of activity of three adolescent slow lorises (N. coucang) was studied in a habitat — simulated, captive environment. The frequency of low, medium and high activity behaviors were recorded under four intensities of illumination (0.061, 0.120, 0.380 and 4.000 footcandles (ft-c)). The data suggest that N. coucang's nocturnal activity level is an inverse function of illumination, with low activity behaviors occurring during moonlight-like intensities and high activity behaviors during twilight-like intensities. The relationship was nonlinear, indicating a threshold mechanism (between 0.120 and 0.380 ft-c) analogous to a crepuscular niche in the wild.     

Functional anatomy of the trunk musculature in the slow loris (Nycticebus coucang)

Lorisid locomotor and postural behaviour exhibits a number of features that distinguish it clearly from other primates. The comparative myological study of the trunk in the slow loris (Nycticebus coucang) and the squirrel monkey (Saimiri sp.) presented here reveals differences that are related to unique aspects of lorisid positional behaviour. While quadrupedal running and leaping requires flexion and extension of the spine, slow climbing quadrupedalism in lorisids depends on spinal lateral flexion and rotation. The contrasting development of the epaxial musculature in the two species dissected reflects these different requirements. Bipedal suspension is a common posture in the lorisids during which rotation and dorsiflexion of the head is made possible by the robustly developed deep, dorsal, cervical musculature. The long lower lever arm in the M. rectus abdominis may play a significant role in the ventroflexion required to regain a quadrupedal stance. © 1995 Wiley-Liss, Inc.     

The chromosome complement of the slow loris (Nycticebus coucang Boddaert, 1785)

The chromosome complements of two male and two female adult slow lorises (Nycticebus coucang) have been studied in blood cultures cultivatedin vitro for three days. We have observed basic differences in arrangement from previous results, and the existence in the complement of a dimorphic pair not described before in this species. This dimorphic pair does not fit with any known type of chromosome dimorphism or polymorphism, either in rodents or primates. The diploid chromosome number is 50. Nine of the chromosome pairs are metacentric, the remaining 15 pairs, submetacentric. The X chromosome is a long submetacentric, ranking 4 in order of decreasing size. The Y chromosome is a rather long metacentric and ranks 15 in the same order. The autosomes, 2 to 10µ long in metaphase with arm ratios ranging from 1.14 to 2.65, are paired and arranged in order of decreasing size. Chromosome pair No. 5 is dimorphic, one of the chromosomes in the pair being constantly longer than the other. An idiogram of the haploid chromosome complement is presented, incorporating measurements of 30 analyzed nuclei.     

Reproduction,physical growth and behavioral development in slow loris (Nycticebus coucang,Lorisidae)

Reproduction of slow loris maintained in in- and outdoor enclosures in the natural day-night-cycle of southern Germany seems to be seasonally dependant. Mating occurs during summer, delivery of offspring during winter. Gestation length as determined from mid-estrus was 186–187 days. Copulation takes place over two to five consecutive days during estrus. Litter size for each of the recorded births was one. Lactation lasts for five to seven months. Sexual maturity is reached at about 1 1/2 to 2 years. Physical growth and the first appearance of main locomotor, behavioral and vocal patterns are described until nutritive weaning. With regard to acoustic structures, the vocal repertoire of newborn slow loris is quite similar to that of adults. During ontogeny main changes are discerned in the temporal pattern and pitch frequency of vocalizations and in their use. Results are compared with other primates.     

The functional anatomy of the ankle and foot of the slow loris (Nycticebus coucang)

The slow loris must use its limb for stabilization and forward progression during arboreal climbing. The orientation of the limb joints, hip, knee, talo-crural, sub-talar and tarso-metatarsal, correlate with movement upon supports lying below and in line with the body axis. The musculature controlling the joints of ankle and foot, and the integument of the sole further indicate the integration of this adaptation.