POPULATION, HABITAT SELECTION AND SOCIAL ORGANISATION OF HANUMAN LANGURS IN CENTRAL KARNATAKA
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2017-08
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Abstract
Hanuman langur are the commonest non-human primate found in India. Although listed as least concern by IUCN, few studies have expressed concerns about local extinction of certain populations due to increasing anthropogenic pressure. The present study was carried out in Gadag district of Karnataka where the environment is unfavourable and langur face high levels of human interference. Demographic data was collected by travelling in existing routes and observing langur troops with binoculars for various group characteristics such as number of adult males, adult females, infant, etc. The occupied tree’s height was also noted for habitat preference data. Spatial data was collected with Garmin eTrex 30x Handheld GPS. The group locations were GPS tagged and the routes travelled were tracked by GPS. Statistical tests were carried out with SPSS v20.0. Overall encounter rate was calculated based on number of groups detected/ 100 km. Variation in encounter rates per day was found to be statistically significant (Paired t-Test, t=9.424, df = 37, p = 0). The mean values of group characteristics were compared to find out any significant differences. The overall mean group size of bisexual groups was 19.57 ±10.94SD. Group size between unimale and multimale groups differed significantly (U = 128.000, P = 0.030). In case of age-sex ratios, only Adult Male to Adult Female ratio differed significantly (U = 80.000, P = 0.001). According to habitat types, the maximum group size was 20.75 ± 10.39SD which was in agricultural habitat and the minimum group size of 13.75 ± 5.75SD was observed in forest habitat.The variation in mean group size, all the demographic parameters and age-sex ratios of bisexual groups was found to be significant. Most groups occurred in agricultural lands. However there was no significant difference in parameters across habitat types. Langur showed marked preference for Neem (Azadirachta indica) and Tamarind (Tamarindus indica) trees. Langur groups showed marked preference towards agricultural plantation, built-up area and scrub forest. Langur groups were found to occupy Barren rocky/ Stony waste habitat about 16 times more than expected. However they avoided substrates such as crop-lands, forest blanks and mining area. Avoidance of croplands could be due to human conflict. In contrary to previous literature, the study site harbours a good population. A broader study covering the adjoining districts falling under Northern Plains will reveal the true status of the population in the region and help in designing proper management strategies to prevent their local extinction.
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