Wildlife Conservation Society scientists recently observed and photographed gorillas (Gorilla gorilla) using sticks as tools. This marks the first time tool use has been documented for the species. Until this discovery, gorillas remained the only species of great ape not observed using tools.

In the first documented observation of tool use, a female gorilla (named 'Leah' by the scientists observing her) used a stick to test the depth of the water she waded through. In the second observation, another female gorilla (named 'Efi') used a portion of a tree trunk to dig for herbs. When finished foraging, she then used the bit of trunk to cover a muddy patch on the ground and serve as a little bridge.

Find out more:

• Gorilla Tool Kit (Wildlife Conservation Society)
• Wild Gorilla Seen Using Tools (BBC News)
• First Observation of Tool Use in Wild Gorillas (PLoS Biology)