Fruticose lichens as a food source for a primate species, Rhinopithecus roxellana: nutritional analysis

Unlike most colobines, the Sichuan snub-nosed monkey (Rhinopithecus roxellana) lives in temperate habitats with strong seasonality and limited plant food availability. R. roxellana mainly relied on year-round available fruticose lichens, an uncommon food source for mammals, supplemented by seasonally available plant food. Fruticose lichens were more easily digestible than plant food. Fruticose lichens contained less feeding deterrents, in particular crude fibers and condensed tannins, than all plant parts. Fruticose lichens also contained more nonstructural carbohydrates than plant leaves. In addition, energy content in fruticose lichens was equivalent to that in some food plant parts. ❧ Fruticose lichens contained less crude proteins than most plant parts. It is unknown how R. roxellana physiologically adapts to the low-protein diet. Lichens produce a range of metabolites that are unique compared to vascular plants. These metabolites have various biological actions (e.g. antibiotic and antiviral), and it is unclear whether R. roxellana eats lichens only for nutrients, or also as a mechanism of self-medication.