Intelligence is subjective, but in general parrots and crows are considered the most intelligent birds. Studies with an African grey parrot called Alex have shown that parrots can associate words with their meanings and form simple sentences. He could vocally label more than 100 objects by colour and shape and quantify numbers of them. Studies have shown that crows such as the New Caledonian crow are also very bright. They can problem solve as well as make and use tools.
Answered by Kate Sherburn, Manchester Museum.