Food selection by folivorous primates is thought to relate to nutrients and plant secondary metabolites. In order to study the condensed tannin of the food plants and its potential influence on food selection of Rhinopithecus bieti, we collected samples of foraging foods (FF) species (n=192) and non-foraging foods (NFF) species (n=188) of Rhinopithecus bieti at Mt. Lasha, Yunnan between April 2010 to March 2012. We measured the condensed tannins (CT) from these samples using the Folin–Denis method. The results showed that the CT contents in monkey’s food were lower than in NFF. The CT content of FF in spring was higher than other seasons. The CT content of FF did not vary significantly in summer, autumn and winter. Among all the FF items, the condensed tannins levels of monkey’s foods were ranked as: buds > flowers > leaves > fruits > lichens. The CT contents in lichen were the lowest all the FF. The CT varied among the different plant parts within a species in different seasons. Buds had the largest average CT in spring. Fruits had the largest average CT in summer and autumn. The CT of leaves was higher than lichen in winter. Monthly average CT of all food species did vary across months. It had the largest average CT (8.36% ± 6.22%) in March and the lowest average CT (1.28% ± 1.19%) in February. Therefore, according to the food species and the supply of temporal-spatial characteristics, the Rhinopithecus bieti may adaopt from high protein fiber ratios/high tannin to low protein fiber ratios/low tannin continuous spectrum foraging strategies.
