Cockatoos are known for their intelligence, having demonstrated the ability to pick locks, match shapes and even ride miniature bicycles along a tightrope.

But now scientists have discovered they are far cleverer, rivalling apes and human four-year-olds in their ability to invent and fashion complex tools to reach food.

Austrian scientists have spent years testing the abilities of Goffin’s cockatoos named Dolittle, Figaro, Kiwi, Konrad, Pipin and Fini at a special laboratory in Vienna.

Now they have now demonstrated the birds are capable of sizing-up the length of poking device needed to reach seeds through a hole in a perspex box, and then make it from a piece of cardboard.

Even when scientists moved the seeds closer to the hole, the cockatoos took a quick glance then designed a tool that was smaller to save effort.

“The way the animals show flexibility in their tool making behaviour between different distances, suggest that they at least learn to pay attention to different conditions” said Dr Alice Auersperg, of the University of Vienna, the head of the Goffin Lab.

“As longer cardboard strips required more parallel bitemarks we have an continuous increase in investment in the manufacture of longer tools and it is likely that the animals were able to save effort.