Is honey a fallback food for wild chimpanzees or just a sweet treat?

Honey is a highly nutritious resource for any primate able to exploit it. Wild chimpanzees exploit nests of honey-making bees (Apini and Meliponini) for honey and brood, typically using tools to overcome the bees' defences. The universality of honey-gathering among modern human foragers in tropical climates and chimpanzees suggests energy-rich honey, acquired with tools, was likely a regular food for ancestral hominins. However, few studies have assessed its role in seasonal foraging strategies of chimpanzees. This study asks whether honey serves as a high-quality fallback food for chimpanzees at Bulindi, Uganda.

Honey consumption was investigated via fecal analysis over 22 months during two studies (Study 1: 2007-2008; Study 2: 2012-2014). Additionally, flower and fruit phenology was measured during Study 1; peak flowering intensity was expected to facilitate increased honey and/or brood production by bees.

Chimpanzees consumed honey (and/or brood) at low frequencies year-round, but bees/beeswax appeared in feces at higher frequencies with decreasing fruit availability (Study 1). Honey consumption was unrelated to flowering and chimpanzees did not consume honey more frequently during the "honey season" when local people harvest beehives. Moreover, consumption was inversely related to fruit intake (both study periods).

Although honey fits the functional definition of a filler fallback food at Bulindi, the chimpanzees unlikely depend on honey to replace nutrients provided by fruit. Overall, honey best qualifies as an energy-dense "treat" during low fruiting months. The data lend support to the hypothesis that tools can facilitate chimpanzees' access to high-quality fallbacks including insect foods when fruit availability is low.