Father-son recognition in hanuman langurs (Presbytis entellus): A field experiment in India

A juvenile male langur, about 15 months old, was removed from his natal one-male-multi-female troop and reintroduced after 3.3 weeks. In attempts to protect the juvenile, his presumed father, the troop's resident male, charged the primatologist who removed and released the individual. After the second removal, the juvenile was introduced into a neighboring male band. The resident male attacked the band members to keep them away from his females. However, after 3.4 weeks of separation, the father and the son recognized each other, because the resident male showed no aggression towards his son and the latter did not run away from him. Kin-recognition is considered to be a mechanism in structuring coalitions within langur male bands.     

Insectivory and its significance to langur diets

Earlier studies on Hanuman langurs (Presbytis entellus) around Jodhpur found them entirely vegetarian (Mohnot, 1974;Winkler, 1988). However, recent observations in the open scrub forests of Jodhpur reveal that scale insects may constitute a regular part of their diet and that insectivory is particularly prevalent in the monsoon months July – September. The insect eating in this habitat seems to support the “Energy/nutrient maximization” hypothesis ofHamilton andBusse (1978).     

Grooming site preferences in female langurs (Presbytis entellus)

Factors influencing grooming site preferences in adult female Hanuman langurs (Presbytis entellus) were investigated. The females belonged to a free-ranging harem troop (Jodhpur, India) and were observed for 569 hr by focal-female sampling. Decisive factors for grooming site preferences were the following: autogrooming was determined mostly by site accessiblity. Allogrooming was significantly concentrated on parts that are inaccessible to the groomee. Close female kin groomed significantly longer, more frequently, and more precisely at inaccessible body parts. Lower-ranking females were groomed significantly less often and more briefly but also more precisely at inaccessible parts. However, the latter might be due to a lower-ranking subjects desire to face away from the higher-ranking groomer in order to avoid eye contact. The data suggest that the groomee determines the sites being groomed.     

Differences in terrestrial velocity in Macaca and Presbytis

Over 150 sequences of terrestrial movement were timed and measured in the toque macaque, the gray langur, and the purple-faced langur to determine the relation between velocity, gait, and psychosocial context. Species differences were found in mean velocity, “favored” gait, and surface preference. All three species used the walk and the gallop at the slowest and fastest speeds respectively. The macaques and gray langurs walked frequently, but the purple-faced langurs were never seen to do so. At intermediate speeds, the macaques used either the “fast” walk or the “slow” gallop, whereas the gray langurs used irregular patterns of walk-gallop-walk-gallop. The purple-faced langurs were faster (about 20 fps) and less variable than the other species, regardless of distance. These data suggest that motor expression varies among the Cercopithecoid monkeys: the correlation between locomotion and anatomy is not as close as it is among wholly terrestrial or arboreal forms; slowness in the macaque is an expression of social confidence, not of biomechanical inability; high speed in the purple-faced langur is due to psychosocial factors rather than to “terrestrial” adaptability.     

Biochemical values of blood serum in the female silvered leaf-monkey,Presbytis cristatus

Thirteen days after capture, the blood serum of eight anesthetized female leaf-monkeys,Presbytis cristatus (3.86 kg of mean body weight), were analyzed for hematocrit (35.6±6.7 %), total protein (6.7±0.8 g/dl), albumin (3.61±0.77 g/dl), α-1 globulin (0.13±0.04 g/dl), α-2 globulin (0.73±0.18 g/dl), β globulin (0.87±0.27 g/dl), γ globulin (1.36±0.55 g/dl), A/G ratio (1.23±0.38), Na (161±6.14 mEq/l), K (5.61±0.74 mEq/l), LDH (575±257 IU/l), GOT (93±67 IU/l), GPT (34±33 IU/l), CPK (250±200 IU/l), ALP (613±633 IU/l), LAP (115±68 IU/l), γ-GTP (28±30 IU/l), TG (47±24 mg/dl), T-Cho (141±31 mg/dl), BUN (29.0±5.7 mg/dl), T-bil (0.21±0.07 mg/dl), and IP (3.4±2.0 mg/dl).     

Social stability and change among forest hanuman langurs (Presbytis entellus)

The social organization of hanuman langurs (Presbytis entellus, Colobinae) was studied in Kanha Tiger Reserve, Central Indian Highlands between 1980 and 1983, followed by six brief return visits over ten years. Censuses of the 7 km² Kanha meadows demonstrated little change in population density and structure between 1982 and 1990; the population was consistently composed of one-male troops and all-male bands. During the return visits the focal C troop extended its known 74.5 ha range by only 5.6%. By 1993 two identified, habituated, adult females remained within the troop. The adult male was resident in C troop for ≥nine years and eight months.     

The social organization of forest hanuman langurs(Presbytis entellus)

The social organization of hanuman langurs (Presbytis entellus;Colobinae) was studied in Kanha Tiger Reserve, Central Indian Highlands, for 2300 hr (1980–1985), in a mosaic of moist deciduous forest and anthropogenic meadow. The langur population density was 46.15/km ² and the mean troop and band sizes were 21.7 and 14.0, respectively. Of 14 troops, 13 were one-male and 1 was trimale. The population adult sex ratio was 1:2.5. The majority of female sexual solicitations was directed toward the harem male. The birth season was December to May, with an estimated gestation of 171–224 days. A review of langur reproductive seasonality suggests that breeding throughout the year is confined to those populations able to exploit human food sources. Mortality during the first year of life was 40%, including infanticide. A significant positive correlation was found between the age of an infant at death or disappearance and the mother’s subsequent interbirth interval. Five cases of social change are described, including female transfer, one-male to multimale change, troop formation, and gradual and rapid replacement of troop males. Takeover-associated infant killing by band males, in an undisturbed moderate-density population, supported the sexual-selection/infanticide hypothesis but not the social-pathology hypothesis. However, it could not be directly confirmed that an invading infanticidal male gains a reproductive advantage. The male tenure of harems was estimated to be 45 months.     

Erosive arthritis and spondyloarthropathy in Old World primates.

Presence of spine and sacroiliac involvement and the nature and distribution of the erosive lesions allow definitive diagnosis of spondyloarthropathy. Thus, spondyloarthropathy was identified in Theropithecus, Papio, Cercopithecus, Macaca, Colobus, Presbytis, and Hylobates. Only monarticular erosive disease was present in prosimians, precluding a diagnosis of spondyloarthropathy for that group. The distribution of erosive disease and axial joint involvement in 1,349 non-prosimian Old World primates is quite characteristic of that noted in human psoriatic arthritis. While Reiter's syndrome must also be considered, the histologic appearance of skin lesions in Macaca is characteristic of psoriasis. Evidence of spondyloarthropathy abounds in the literature of primate skeletal disease. Environmentally based contagions may be important in the pathophysiology of spondyloarthropathy. The wide geographic distribution of the phenomena in monkeys suggests a "panendemic," with limited individual susceptibility (compared to that noted in gorillas and chimpanzees). Identical occurrence of erosive arthritis/spondyloarthropathy in free-ranging and artificially restrained animals suggests that spondyloarthropathy can validly be studied in artificially restrained populations. This perspective should allow application of human therapeutic approaches to and perhaps improve the quality of life for artificially restrained, afflicted individuals.     

Sociobiology of Hanuman langurs (Presbytis entellus): introduction into the Jodhpur field project

The conceptual development of a longterm project on Hanuman langurs (Presbytis entellus) is described. The joint indo-german project was performed at Jodhpur, India, starting in 1977. Its main aim was to study the interrelations between individual life histories and troop histories. A general overview of the habitat and the langur population is presented.     

Locomotor behavior and muscular anatomy of sympatric Malaysian leaf-monkeys (Presbytis obscura and Presbytis melalophos).

Sympatric Malaysian leaf-monkeys, Presbytis obscura and Presbytis melalophos show quantitative differences in their use of different locomotor patterns during daily activities. P. obscura primarily moves quadrupedally along large boughs; P. melalophos relies more on leaping between smaller supports. P. melalophos also uses forelimb suspension more than does P. obscura. Comparison of the muscular anatomy of the shoulder, arm, trunk, hip and thigh show numerous statistically significant differences between the two species in relative mass of individual muscles and in details of muscular origin and insertion. In almost all instances these differences accord with the types of differences in muscular anatomy predictable from either biomechanical analyses of locomotor behavior or comparative anatomical studies of other mammalian species.