Tool-use to obtain honey by chimpanzees at Bulindi: new record from Uganda

Abstract

Honey-gathering from bee nests has been recorded at chimpanzee (Pan troglodytes) study sites across tropical Africa. Different populations employ different strategies, ranging from simple 'smash-and grab' raids to use of sophisticated tool-sets, i.e., two or more types of tool used sequentially in a single task. In this paper I present evidence of tool-use, and the probable use of a tool-set, for honey-gathering by unhabituated chimpanzees at Bulindi, a forest-farm mosaic south of the Budongo Forest in Uganda. Between June and December 2007, 44 stick tools were found in association with 16 holes dug in the ground, corresponding to the period when stingless bees (Meliponula sp.) appeared in chimpanzee dung. In 11 cases the confirmed target was a Meliponula ground nest. Two potential tool types were distinguished: digging sticks encrusted with soil, and more slender and/or flexible sticks largely devoid of soil that may have functioned to probe the bees' narrow entry tubes. Reports of chimpanzees using tools to dig for honey have been largely confined to Central Africa. Honey-digging has not previously been reported for Ugandan chimpanzees. Similarly, use of a tool-set to obtain honey has thus far been described for wild chimpanzee populations only in Central Africa. Evidence strongly suggests that Bulindi chimpanzees also use sticks in predation on carpenter bee (Xylocopa sp.) nests, perhaps as probes to locate honey or to disable adult bees. These preliminary findings from Bulindi add to our understanding of chimpanzee technological and cultural variation. However, unprotected forests at Bulindi and elsewhere in the region are currently severely threatened by commercial logging and clearance for farming. Populations with potentially unique behavioral and technological repertoires are being lost.

The influence of ecology on chimpanzee (Pan troglodytes) cultural behavior: A case study of five Ugandan chimpanzee communities.

“…Although these results still demand further confirmation, they currently suggest that stick use is absent throughout Budongo Forest. It is also interesting that some of the communities living in fragmented, isolated forest patches adjacent to Budongo (some 25 km from the main block) are thought to use sticks during foraging (McLennan, 2011b;Reynolds, 2005;J. Wallis, personal communication, 2010).…”

Bili-Uéré: A Chimpanzee Behavioural Realm in Northern Democratic Republic of Congo

“…Chimpanzees in northern Uganda, for example, especially Budongo, have a smaller tool repertoire and use few or no stick tools [McLennan, 2014]. We can now document a number of possible large-scale patterns or "behavioural realms": the use of clubs to pound open beehives in Central African chimpanzees [Fay and Carroll, 1994;Hicks, 2004;Hicks et al, 2005;Boesch et al, 2009;Sanz and Morgan, 2009], honey-digging as primarily a central and eastern chimpanzee behaviour [Hicks et al, 2005;McLennan, 2011;Estienne et al, 2017a, b; but see Boesch and Boesch, 1990, for an example in West Africa], termite nest perforation in Central Africa [Sanz and Morgan, 2007] and nut-cracking in western chimpanzees [Boesch et al, 1994;Boesch and Boesch-Achermann, 2000].…”

“…A number of recent long-term sites have added entire new tool types to the species' repertoire, such as complex tool sets (Goualougo, Republic of Congo [Sanz and Morgan, 2007]; Loango, Gabon [Boesch et al, 2009]) and spears used to skewer bushbabies (Galago senegalensis) (Fongoli, Senegal [Pruetz and Bertolani, 2007]). New study sites have also expanded the range of previously discovered behaviours by hundreds of kilometres (honey-pounding at Loango [Boesch et al, 2009]; honey-digging at Bulindi, Uganda [McLennan, 2011]). Other shorter-term studies have revealed new behaviours ranging from brush-tipped fluid probes to "stepping sticks" and "seat sticks" (Tenkere, Sierra Leone [Alp, 1997]).…”

<Note> Preliminary Observations of Hand-Clasp Grooming by Chimpanzees at Bulindi, Uganda

“…(see Figure 1). Bulindi chimpanzees use tools to excavate subterranean bee nests for honey-a behavior not recorded at Sonso or elsewhere in western Uganda 12 . The occurrence of GHC at Bulindi provides further evidence of behavioral variation among chimpanzees in the Budongo region.…”