New Caledonian crows make hooked tools from soft twigs to scoop insects out of holes. Other animals that use tools: chimpanzees, parrots, alligators and crabs.
The crows found the desired stems even when they had been disguised with leaves from a different plant species.
Convergent Evolution: The crows lack a neocortex (assumed to enable advanced cognition). They instead have densely packed clusters of neurons.
We’re not the best at every mental task, e.g. chimps have better short-term memories. Ranking the intelligence of animals might be pointless. The real question is how well that animal is adapted to its niche.
A New Caledonian solved an artificially constructed puzzle involving 8 distinct steps. It had learned how the individual steps work, but solving them in sequence is a greater challenge.
Crows have a natural curiosity. They cheekily grab scientific equipment and fly off with it in the aviary. Young birds especially love to play.