Clever crows can assemble tools from two or more components without any help, a feat previously seen only in humans and great apes. The birds were filmed slotting together rod pieces to create a tool long enough to extract a morsel of food which scientists had hidden away. In one experiment, they were presented with disassembled syringes, and created the right length of tool without any prompt or demonstration. The birds' ability to anticipate what an unseen object will be able to do matches the intelligence of a human toddler, Oxford University researchers said. The animals in the experiment were New Caledonian crows - a species native to a large Pacific island east of Australia of the same name.