Semnopithecus priam

Abstract: Hybridization is increasingly recognized as an important mechanism of evolutionary change in the order Primates. Here, we present the first observational data supporting natural hybridization between the critically endangered purple-faced langur (Semnopithecus vetulus philbricki) and the threatened tufted gray langur (Semnopithecus priam thersites) in Kaludiyapokuna Forest Reserve in Sri Lanka. In one case study, we observed a long-term (> 1 year) mixed-species group consisting of one adult tufted gray langur male coexisting with seven adult purple-faced females. Although copulations were not observed, two infants were conceived during the male’s tenure, and the coat color of one of these infants transitioned into that intermediate between those of the two langur species. The tufted gray langur male was also aggressive toward extra-group males of both species, as well as towards purple-faced juveniles within his group. However, we never witnessed the male exhibiting aggression towards the infants conceived during his tenure. In a second case study, a female purple-faced langur visited and sexually solicited a tufted gray langur male in a known study group of this species over the course of 2 days, in what resembled a sexual consortship. Taken together, the observed mixed-species association and attempted interspecific mating suggest that hybridization is very likely in these sympatric species. Genetic data are needed to confirm and determine the extent of hybridization in the dry zone of Sri Lanka where purple-faced langurs live in sympatry with tufted gray langurs.

Abstract: Life history traits evolve such that the reproductive output of an organism is maximized. Demographic characteristics, a consequence of life history traits, indicate the reproductive output per individual in group-living species. Both phylogenetic and ecological factors influence demographic traits. In the forests of the Western Ghats, India, we studied the demography of three langur species: Semnopithecus johnii, a wet forest-dwelling species; Semnopithecus hypoleucos, largely a wet forest-dwelling species; and Semnopithecus priam, a primarily dry forest-dwelling species. S. hypoleucos and S. priam are genetically closer to each other than to S. johnii. We sampled a total of 193 groups of the three species of langurs. The group size was smaller in the two wet forest-dwelling species, S. johnii (median = 10) and S. hypoleucos (nine), than in the dry forest-dwelling species, S. priam (18). The number of adult females per group was higher in S. priam (seven) and S. johnii (six) than in S. hypoleucos (four). On the other hand, the adult female:immature ratio, indicating reproductive output and life history, was highest in S. johnii (1:0.33) followed by S. hypoleucos (1:1) and S. priam (1:1.09). Our results suggest that reproductive output is lowest in the arboreal wet forest species and increases as the species become somewhat dry deciduous forest dwellers, or almost facultative dry forest dwellers, and relatively more terrestrial. Some traits, such as group size, appear to be more sensitive to ecological factors, and some other traits such as age-sex ratios and reproductive output appear to be more conservative.

Abstract: The Dry zone grey langur (Semnopithecus priam thersites) is a subspecies endemic to Sri Lanka. In this research investigated the population distribution, threats and conservation status of the S. priam thersites in the contiguous forest of Mihintale Sanctuary in Sri Lanka. Population study done by direct counting and vocal sounds along the permanent line transects. Threats were identified by using a questionnaire survey. A total of 03 troops and least 60 individuals were recorded during the study period from December 2009 to May 2010. These three troops were sighted in Kaludiyapukuna forest (19 individuals), Rajagiri lena forest (21 individuals) and the boundery near kumarasirigama village (18 individuals). The remaining populations living almost completely in disturbed habitats due to human influences. The average group sizes were 16.8±2.65 and 19.14 ±3.76 in forested areas and forests neighboring human habitation respectively and the all three groups were recorded as multimale groups. The troop‟s distribution varied with the food availability and restricted to human habitation and disturbed forest patches. The species is vulnerable to hunting and retaliatory killing in response to crop damage.

Abstract: We collected the data of the activity budget and diet for a group of Tufted grey langurs Semnopithecus priam priam (TGL) in Pothigaiadi rural village from 2019 to 2020. This population is unstudied...