Prospects for Bonobo Insectivory: Lui Kotal, Democratic Republic of Congo

Abstract

Chimpanzees (Pan troglodytes) are well-known to eat invertebrates, especially social insects, across Africa, but allopatric bonobos (P. paniscus) are not. Bonobo insectivory is sparsely documented and apparently sporadic. However, the availability to bonobos of social insect prey and raw materials with which to make tools to exploit them is unknown. Here, we test a set of hypotheses that relates to questions of presence, abundance, density, and distribution of taxa that Pan consume and of vegetation suitable for making extractive foraging tools. We worked at Lui Kotal, Democratic Republic of Congo, where unprovisioned bonobos live in intact forest, far from villages. We collected insect and fecal specimens, transected for prey and assessed raw materials, and monitored mounds of Macrotermes. All but 1 of the major taxa of relevant termites, ants, and (stinging) honey bees were present. The 3 main taxa of insects that chimpanzees elsewhere eat -Macrotermes (fungus-growing Int J Primatol (termites), Dorylus (Anomma; army or driver ants), and Apis (honey bees)-were abundant and widespread, and usually at densities exceeding those at well-known chimpanzee study-sites. Similarly, woody and nonwoody vegetation suitable for making fishing probes was common at mounds of Macrotermes. There is no obvious ecological reason why bonobos should not use elementary technology in extractive foraging, e.g., termite-fish, ant-fish, ant-dip, honey-dip, to obtain social insects.

Orangutan tool use and the evolution of technology

“…Apes with extractive foraging have larger tool repertoires than the other apes (bonobos, gorillas) (McGrew et al, 2007;Deblauwe & Janssens, 2008;Deblauwe, 2009;Lonsdorf et al, 2009;Bentley-Condit & Smith, 2010), and among monkeys the only taxa with habitual tool use comprise extractive foragers that use tools mainly extractively (long-tailed macaques: Gumert et al, 2009;capuchins: Visalberghi, 2009). Intelligence may compensate to some extent for the lack of an innovation bias toward the extractive-foraging context, but it has a limited effect on the occurrence of tool innovations in general, and even less on the occurrence of habitual tool use or tools used for extractive foraging.…”

<Note> Ecological Aspects of Chimpanzee Insectivory in the Budongo Forest, Uganda

“…To estimate productivity, that is, amount of termites available to harvest, SH randomly sampled 10 Cubitermes and two Pseudacanthotermes mounds, removing about 150 cm 3 from their tops. Once sealed in a ziplock bag, the soil was broken into chunks of less than 1 cm 3 ; all termites, by caste, were counted in the contents 7 . Also, SH made and used flexible probes modelled on chimpanzee fishing probes, to fish termites from these mounds.…”

“…This dearth is puzzling, especially when these sites are compared with those (Gombe, Mahale) of neighbouring Tanzania, which have well-documented and varied elementary technology 5,6 . Lack of insectivory could refl ect basic environmental constraints: Absence or scarcity of prey species, or absence or scarcity of raw materials for tools 7 . Less likely alternative explanations are differences between Ugandan and non-Ugandan populations in terms of genome, diet, manual dexterity, intelligence, or appetite.…”

On the tool use behavior of the bonobo‐chimpanzee last common ancestor, and the origins of hominine stone tool use

“…In contrast, wild bonobos have been found to use tools relatively rarely [Hohmann & Fruth, 2003], especially for the kinds of extractive foraging tasks at which chimpanzees excel, and despite the presence of suitable tools and prey species [McGrew et al, 2007]. This situation can cause anomalies in phylogenetic reconstructions: for example, Duda & Zrzavy [2013, Table IV] recently used a broad suite of characters to assess ape life history and behavioral evolution, concluding that there is Contract grant sponsor: European Research Council Starting (PRIMARCH); contract grant number: 283959. statistically significant support for simple tool use in the LCAs of all great apes, all African great apes, and the human-Pan LCA, but not the Pancestor ape, in which tool use is considered "likely" instead.…”