Tool use during display behavior in wild cross river gorillas

Abstract

During the course of a 3-year ecological study on Cross River gorillas (Gorilla gorilla diehli) at the Kagwene Mountain in Cameroon, we observed three cases of tool use which may be unique to the gorillas of this region and possibly learned through interactions with humans. A non-habituated group of Cross River gorillas threw fistfuls of grass toward humans in display contexts. An individual gorilla was also observed to throw a detached branch toward researchers during another encounter. The third encounter occurred between the focal group and a local man, in which the man threw stones at the gorillas and they reacted by throwing fistfuls of grass back at him. We describe these observations and speculate that this sub-population of gorillas developed this display behavior as a response to particular local conditions.

A comparison of bonobo and chimpanzee tool use: evidence for a female bias in the Pan lineage

“…van Schaik, personal communication), the only other skilful ape tool-users in the wild. Data on gorillas, Gorilla gorilla, whether in the wild (Breuer et al 2005;Wittiger & Sunderland-Groves 2007) or in captivity (reviewed in Lonsdorf et al 2009), are too limited to draw conclusions. Apart from apes, a female bias in tool use has also been found in dolphins (Tursiops sp.…”

“…Second, it is also possible that tool use in wild bonobos has simply been underestimated because long-term observations are absent and because the number of studied groups is still small (Hohmann & Fruth 2003). Before firm conclusions can be made, more data on bonobo and gorilla tool use are needed, beyond the existing records (bonobos : Kano 1982;Ingmanson 1996;Hohmann & Fruth 2003;gorillas: Breuer et al 2005;Wittiger & Sunderland-Groves 2007). Studies that focus on the cognitive abilities underlying tool use are equally relevant.…”

Nesting Behavior of Gorilla gorilla diehli at Kagwene Mountain, Cameroon: Implications for Assessing Group Size and Density

“…It is unknown how frequently gorillas come into contact with either cattle or humans other than researchers, but local people farm and graze domestic animals in close proximity to the gorillas and cattle use water sources within the forest. Gorillas may therefore come in to contact with people and cattle on a regular basis and may regard them as intruders rather than a direct threat (Wittiger and Sunderland-Groves 2007). Our data strongly suggest that the high proportion of arboreal nests at Kagwene is influenced by heavy seasonal rainfall.…”

Functionality in Tool Use in Western Lowland Gorillas (Gorilla gorilla gorilla)

“…Koga was observed being in contact with, hitting, and throwing the bucket in the majority of his observed interactions, but these were not behaviors for which bucket functionality was irrelevant. Throwing objects as an agonistic display has been observed in gorillas in the wild (Wittiger & Sunderland-Groves, 2007) Koga was not observed to fill the bucket, but was observed on three occasions drinking from an already filled bucket. On two instances, he was observed to displace one of the females from her bucket after she had filled it (or tried to fill it if it was nonfunctional).…”