LEAF CHEMISTRY AND FOOD SELECTION BY COMMON LANGURS (PRESBYTIS-ENTELLUS) IN RAJAJI-NATIONAL-PARK, UTTAR-PRADESH, INDIA

Food selection in folivorous primates has been hypothesized to be corr elated with leaf chemistry. To test this hypothesis, we conducted a 5- month study on Presbytis entellus in a moist deciduous forest in the R ajaji National Park, Uttar Pradesh, India. The study period covered tw o seasons, winter and spring. We used the percentage time spent feedin g on each food item as an index of food selection, which we estimated from group scan data collected from one study group for 6 days each mo nth. We estimated the selection ratio for each item as the ratio of ti me spent feeding to availability. We estimated food availability from vegetation sampling and phenological data in the home range of the stu dy group. We estimated crude protein (CP), acid detergent fiber (ADF) and tannins in mature and young leaves of 12 major food species in the laboratory. Food selection is positively correlated with CP in winter and negatively correlated with ADF in both seasons. It also is correl ated with CP/ADF ratio, but to a lesser extent than the best predictor in winter and spring. Selection ratio is not correlated with CP and A DF in both seasons. It is probable that the inclusion of other factors , such as micronutrients, condensed tannins, and digestibility, might give a better prediction of food selection.