This video says about itself:
Ravens – the most intelligent birds in the world
1 September 2015
There are Corvids around the world. An evidence for their adaptability. They were highly revered in most cultures because of their intelligence, but with the civilization their image changed. The walls of the moated castle Hallwyl accommodate a jackdaw colony since it was built around 1200. In the shaft of this medieval castle a jackdaw couple build a nest. There are jackdaws also in the castle in Starnberg. Biologist and behavioral scientist Princess Augusta of Bavaria examined precisely the jackdaws and identified in them a highly developed intelligence. In addition to several species of monkeys, crows are the only animals which can make tools and use them meaningfully.
July 13, 2017
Despite previous research that indicates such behaviors are unique to humans and great apes, a new study shows that ravens, too, can plan ahead for different types of events , and further, that they are willing to forgo an immediate reward in order to gain a better one in the future. As ravens and great apes have not shared a common ancestor for over 300 million years, these results suggest that the cognitive “planning” abilities they share in common re-appeared, on a separate evolutionary path, in the birds.
The complex cognitive task of planning ahead has almost exclusively been observed in humans and great apes. Some corvids, a family of birds that includes ravens, have also demonstrated the ability to plan beyond the current moment — but such findings have been confined to caching food.
Here, Can Kabadayi and colleagues sought to further explore the ability of ravens to plan ahead through a series of experiments. First, ravens were trained to use a tool to open a puzzle box in order to access a reward. The ravens were then presented with the box, but not the tool. The box was removed and one hour later the ravens were given the opening tool, as well as several “distractors.”
Nearly every raven chose the correct, apparatus-opening tool; upon being presented with the box 15 minutes later, they used the tool to open it, with a success rate of 86%. A high success rate (78%) was also seen in similar experiments where ravens used a token to later barter for a reward. The ravens planned for bartering more accurately than apes, the researchers report, and they were on par with them in the tool-using tasks, despite lacking predispositions for tool handling.
Next, the ravens were presented with the correct, apparatus-opening tool, distractor tools, and an immediate reward, but were only permitted to select one item. The immediate reward was less appealing than the reward in the box, the researchers report, demonstrating a level of self-control in the birds similar to that seen in apes.
See also here.