Status and distribution of golden langurs (Trachypithecus geei) in Assam, India.

The distribution of golden langurs (Trachypithecus geei) is limited to a small area of western Assam in northeast India and Bhutan between the rivers Manas in the east, Sankosh in the west, and Brahmaputra in the south. It is one of the most seriously endangered primate species of India. A comparative analysis based on satellite images taken in 1988 and 1998 showed a 50% loss of original golden langur habitat. Data on population dynamics collected using line transect and total count methods are presented here. An average group size of 8.2 (range 4.0-22.0) individuals was recorded. A total of 1,064 individuals were counted living in 130 groups. The sex ratio was 1.9-2.5 adult females for each adult male. A low percentage of juveniles and infants suggests that the population is unstable. Most of the groups had only one adult male. Small group sizes, isolated distribution, proportionately few infants and juveniles, and degrading habitat are all causes of concern. Demographic trends indicate a decline in the golden langur population.