Using tools was once thought to be one of the defining features of humans, but examples of it were eventually observed in primates and other mammals. But the biggest surprise came when birds were observed using tools in the wild. After all, birds are the only surviving dinosaurs, and mammals and dinosaurs hadn't shared a common ancestor for hundreds of millions of years.
The authors note the corvids and parrots are so widely separated within the birds' evolutionary tree that it's unlikely that they had a common, tool-using ancestor. They argue that, although we tend to think of tool use as a distinctive mental capacity, it might be more accurate to consider it as a possible outcome of having some minimum level of what they call "physical intelligence." Goffin’s cockatoos don't normally exercise this capacity but, under the right circumstances, it can be uncovered.