Influences on Gum Feeding in Primates

Abstract

This chapter reviews the factors that may affect patterns of gum feeding by primates. These are then examined for mixed-species troops of saddleback (Saguinus fuscicollis) and mustached (Saguinus mystax) tamarins. An important distinction is made between gums produced by tree trunks and branches as a result of damage and those produced by seed pods as part of a dispersal strategy as these may be expected to differ in their biochemistry. Feeding on fruit and Parkia seed pod exudates was more prevalent in the morning whereas other exudates were eaten in the afternoon. This itinerary may represent a deliberate strategy to retain trunk gums in the gut overnight, thus maximising the potential for microbial fermentation of their beta-linked oligosaccharides. Both types of exudates were eaten more in the dry than the wet season. Consumption was linked to seasonal changes in resource availability and not the tamarins' reproductive status, providing no support for the suggestion that gums are eaten as a primary calcium source in the later stages of gestation and lactation. The role of availability in determining patterns of consumption is further supported by the finding that dietary overlap for the trunk gums eaten was greater between species within mixed-species troops within years than it was within species between years. These data and those for pygmy marmosets (Cebuella pygmaea) suggest that patterns of primate gummivory may reflect the interaction of preference and availability for both those able to stimulate gum production and those not.