RESUMO
While all great apes have been documented to use tools, gorillas are arguably the least proficient tool users. In 2009, a Western lowland gorilla (Gorilla gorilla gorilla) at the Buffalo Zoo was observed using a bucket, which had been provided as part of normal enrichment, as a tool to collect water. We conducted a brief, ad libitum investigation to confirm the validity of the initial observation. We then carried out a systematic investigation of the behavior in 2010. We collected 72 hr of videotaped data and tested the null hypothesis that the gorillas did not differ in their prevalence of engaging in bucket-use behaviors. We documented that all four adult gorillas in the group used buckets as drinking tools; however, there was significant individual variation in frequency and type of use of buckets. Four of the eight behaviors showed significant variation among individuals. The silverback male and the youngest adult female contacted and held the bucket significantly more than the remaining two adult females. The young female carried and drank from the bucket significantly more than any other individual. Furthermore, she was observed to fill the bucket with water four of the six times during which this behavior was observed. These data provide evidence of the ability of gorillas to utilize tools, given the appropriate environmental conditions. We continue to explore the abilities of gorillas to recognize the functionality of buckets as tools.