Behavioural ecology of the silver leaf monkey, Trachypithecus auratus sondaicus, in the Pangandaran Nature Reserve, West Java, Indonesia

摘要

The ecology of the silver leaf monkey, Trachypithecus auratussondaicus, was studied in the Pangandaran Nature Reserve, WestJava, Indonesia. The Reserve comprises two sections: the CagarAlam (CA) (Nature Reserve proper) consisting largely of secondaryforest; the Taman Wisata (TW) (public-use zone) consisting of mixedsecondary forest and plantation areas (teak, mahogany and acacia).Two groups of similar age/sex class composition were selected fordetailed study; one in the CA (GRP21) and one in the TW (GRP3).Their behavioural ecology was compared with respect to thestructure, floristics and phytochemistry of the habitats.Trachypithecus auratus formed groups of 6-21 individuals withone or two adult males. Home-range areas were actively defended.Major food items were young leaves and fruits. Several specieswere asynchronous in production of reproductive parts and youngleaves such that food was generally abundant. Food items tended tobe lower in fibre content and were more digestible than vegetationwhich was not eaten. Phenolics and condensed tannins were not amajor determinant in food selection. The protein/ ADF ratio did notexplain selection of specific parts of food items by T. auratus norwas the difference in biomass of T. auratus in the CA and TWattributable to the ratio of these measures in mature foliage.GRP21 had a larger home-range area, travelled further in a day,had a higher dietary intake of fruit and spent more time travellingand resting than GRP3. GRP3 spent more time feeding than GRP21.Day-range length was positively correlated with the proportion offruit in the diet for both groups and negatively correlated with theproportion of leaves in the GRP3 diet.Young teak (Tectona grandis) leaves were the single mostcommon food item for GRP3. Teak trees were distributed in large,relatively homogeneous patches. By comparison, major dietaryitems of GRP21 were distributed in smaller, widely spaced, patches.The TW supported a higher biomass of T. auratus distributed inlarger groups than in the CA. In plantation areas, teak leaves (not ahighly preferred dietary item) provided a constant source of foodwhich was exploited when preferred items were scarce.