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WHY PRIMATES CONSUME THE INNER BARK OF TREES IN PLANTATIONS?
Primates bark-strip trees in forest plantations in several tropical and subtropical countries, producing large economic losses and generating a conflict of difficult solution. How many primate species engage in this behavior, which plantations (tree species) and countries are the most affected and, especially, what are the causes of this behavior? To answer these questions, we conducted a literature review on this topic, searching for papers, theses and reports focusing on bark-stripping of trees by primates in forest plantations. We compiled a data set consisting of 51 documents of which 46 corresponded to primates bark-stripping trees in forest plantations and five in managed forests. We also used maps of tree plantations in Brazil and IUCN maps of the distribution of capuchin monkeys in the genus Sapajus to assess if the black capuchin monkey (Sapajus nigritus) has a higher innate tendency to bark-strip trees than other capuchins or if the predominance of reports of this species producing damage to trees in plantations results from the fortuitous overlap of plantations of preferred tree species with its distribution. Thirteen non-human primate species bark-strip trees of commercial value worldwide. Three of these, the chacma baboon (Papio ursinus), the black capuchin monkey and Sykes´s monkey (Cercopithecus albogularis), are responsible for most of the damage reported in large scale plantations. They affect tree plantations in five African (mostly in South Africa and Zimbabwe) and two South American countries (Brazil and Argentina). These omnivorous species tend to concentrate their damage on plantations of coniferous trees (Pinus sp. and Cupressus sp.). The trees more frequently bark-stripped by primates are Pinus taeda, Pinus patula, and Pinus elliotti, with 15, 14 and 10 reports each. Eucalyptus plantations are less frequently affected by gorillas, two colobine monkeys, howler monkeys, capuchins, baboons and chimpanzees. Bark-stripping of pines tends to be more seasonal than that of Eucalyptus, and their damage of higher incidence and intensity. Of the tree plantations reported in Brazil, 53% correspond to Eucalyptus, 23% to Pinus and 24% to other tree species. Of the circa 20,000 km2 of pine plantations located within the distribution range of Sapajus in Brazil, 94% are found within the range of the black capuchin, a capuchin species that occupies only 10.6% of Sapajus range in this country. This overlap explains why the black capuchin (and not other Sapajus species) is so frequently reported bark-stripping trees in plantations in Brazil. The most frequently cited hypothesis for why primates bark-strip trees in plantations is that the inner bark (phloem) is a fall-back resource consumed during periods of food scarcity. However, this and other hypotheses, such as sap as a source of water, or medicine, are not generally supported by empirical evidence. Eucalyptus bark may be consumed for its high sodium content. The phloem of pines seems to constitute a profitable food source consumed by primates during the growing season of this tree. If these hypotheses were correct, sodium supplementation may alleviate damage to Eucalyptus plantations and diversionary feeding could be used to mitigate damage to pine plantations.
Pine plantations, Macaco prego, Sapajus nigritus
Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET) and Facultad de Ciencias Forestales, Universidad Nacional de Misiones, Argentina.
Biologia da Conservação
Mario Santiago Di Bitetti, Juan Ariel Insaurralde