3.3 Food choice
The langurs showed significant selectivity in their diet composition throughout the year. Among the 115 food species (including three non-plant components and 11 plants whose species names could not be identified) that François’ langur consumed throughout the year, only 23 plants (20%) accounted for more than 1% of the total foraging records but contributed to 72.99% of the foraging records. Among the 23 species of plants, Ficus concinna, Cuscuta chinensis, Boniodendron minus, Pittosporum pulchrum Gagnep., Flueggea virosa (Roxb. ex Willd.) Royle, Pithecellobium clypearia (Jack) Benth., Pericampylus glaucus (Lam.) Merr., Vitex kwangsiensis C. Pei, Cudrania cochinchinensis(Lour.) Yakuro Kudo & Masam., and Erythropalum scandens Blume were among the top 10, contributing to 49.06% of the foraging records.
The François’ langurs did not consume plants within each family evenly. They used 68 (45.3%) of the 150 plant species marked by the vegetation surveys in the overall foraging record, which accounted for 89.04% of the total foraging record (Table 5). Among the top ten tree species in the vegetation surveys, only Flueggea virosa accounted for more than 2% of the total foraging records. The correlation analysis showed that there was no significant correlation between the foraging ratio and relative density of these 68 plants (Spearman Rank Correlation Coefficient rs = 0.146, n = 68, P > 0.05), indicating that there was no strong correlation between the François’ langur’s food choice and the number of plants in the environment.