Context-dependent tool use in New Caledonian crows.

Humans and chimpanzees both exhibit context-dependent tool use. That is, both species choose to use tools when food is within reach, but the context is potentially hazardous. Here, we show that New Caledonian crows used tools more frequently when food was positioned next to a novel model snake than when food was positioned next to a novel teddy bear or a familiar food bowl. However, the crows showed no significant difference in their neophobic reactions towards the teddy bear and the model snake. Therefore, the crows used tools more in response to a risky object resembling a natural predator than to a less-threatening object that provoked a comparable level of neophobia. These results show that New Caledonian crows, like humans and chimpanzees, are capable of context-dependent tool use.