Survey and census of hoolock gibbon (Hoolock hoolock) in the Inner-Line Reserve Forest and the adjoining areas of Cachar district, Assam, India.

A detailed survey of Hoolock hoolock was carried out in the Inner-Line Reserve Forest and the adjoining areas of Cachar district of southern Assam, India, from July 2010 to December 2011. About 150 km2 of the area was covered. In direct sighting, groups and individuals were counted in 7 localities (39.7 km2). Only 3.96 km2 of the actual forest area were occupied by these gibbons. Nine family groups and a solitary subadult, 33 individuals in all, made up the total count. Of these, adult males and females comprised 54.5% of the population while the subadults, juveniles and infants comprised 27.3, 12.1 and 6.1%, respectively. Each family group's home range was 0.31-0.51 km2. Of the 7 localities, only 1 had more than 1 family group. Habitat destruction and diverse threats to the hoolock gibbon in this area are examined in this paper.

The enigmatic Arunachal macaque: its biogeography, biology and taxonomy in Northeastern India.

The purpose of this study was to determine the taxonomic status of an unidentified enigmatic macaque seen by scientists since the late 1990s in Arunachal Pradesh, India. We surveyed 49 troops of enigmatic macaques in four districts of Arunachal Pradesh. The population studied is from the macaque sinica-group as defined by the reproductive organs. The main species-separating trait in the sinica-group is tail length to head and body length ratio that decreases with latitude and elevation. We gathered data on morphology, pelage descriptions, tail to head and body ratios and tail to hind foot ratios from photos and live animals (43 individuals from 36 areas) within the range of and between the two subspecies of the Assamese macaque (Macaca assamensis). We compared the data to six western Assamese macaques and studies of Assamese macaques and related species. We found great variability in tail length, pelage color, facial skin color, and facial and hair patterns. The tail/head-body and tail/foot ratios, although varied, supported the hypothesis that these enigmatic forms were part of a population of Assamese macaques found in the gap between the two subspecies ranges and were not a new species as described earlier. Instead, we found evidence that darker pelage, larger body size, and shorter tails occur at higher elevations and latitudes similar to the general trend in the sinica-group's adaptations to colder climates. Thus, the population may be important for its variation, throwing light on the speciation process and how the northern species of Tibetan macaques evolved from an ancestor similar to the Assamese macaques as adaptations to a colder climate.