Intentional ingestion of wax scales (Ceroplastes sp.) in a group of Alouatta caraya in the Argentinean Wet Chaco

PÉREZ-RUEDA MA; CANTARELLI VI; RAÑO M; KOWALEWSKI MM

Congreso; XV Congreso Brasileño de Primatología. Recife, PE (Brasil); 2013

Alouatta caraya like all other howlers are folivorous-frugivorous primates. Howler monkeys are highly selective feeders and rely on slow and efficient digestion to extract energy and nutrients locked up in leaf structural carbohydrates. A strategy of energy minimization, moving little and resting for long periods of time each day, allow them to subsist predominantly on a diet of hard to digest leaves. However, several field studies report that arthropods may be inadvertently ingested with the vegetable matter and there are also observations of intentional consumption of bird eggs during periods of food scarcity. Here we report intentional consumption of wax scales, Ceroplastes sp. We observed 2 free-ranging social groups of Alouatta caraya living in the protected area of Chaco National Park, in Northern Argentina (26° 40?S, 59° 48?O). We recorded behavior via focal animal-sampling to estimate activity pattern and diet composition form February to March 2012. We only observed wax scale feeding in one group, although the scales were available for both groups. All group members (n=5) consumed scales. Their feeding time represented 19.91% of their activity budget, and they devoted 53% of this time to feed on new leaves, mature leaves and shoots, 38% to fruits, 7% to scales, and 2% to others. Expansion of dietary animal-matter intake is based on facultative foraging responses to temporary pulses in animal matter availability. The digestibility of animal protein is higher than that of plant protein. Scales also produce large amounts of honeydew, and this could represent an extra source of carbohydrates that attract howlers to feed on them. Dietary flexibility of black and gold howler monkeys is higher than we thought and we might underestimate animal matter consumption. Feeding behavior is often difficult to observe, especially for arboreal primates, and insect ingestion can be easily overlooked.