Among researchers studying Corvids, Lawrence Kilham and Bernd Heinrich are perhaps the best known. Both deem the Raven Corvus corax
to be the most intelligent of animals excelling even the Chimpanzee in problem solving ability and speed of learning. The claim is that the raven is the Einstein of the avian world.
There is a strange coincidence here. Back in 1905 when Albert Einstein published the Special Theory of Relativity King Raven flew from roost to roost declaring that Einstein was the Raven of the Mammalian world. All the other ravens looked up, nodded agreement, and then went on eating.
Lawrence Kilham relates that in 1933 he was in northern Greenland intent on collecting bird and mammal specimens for the Museum of Comparative Zoology. He writes that he doesn't like to shoot things but at that time there was no talk of ecology or conservation. On the beach were some 200 ravens,tame as chickens, swarming on the shingle where fish were being cleaned. He could not shoot one there with so many people around, and going further inland he found there were no birds to be seen. However one morning he did see one bird circling overhead and raising his 12 bore shotgun took a shot at it. One small black feather drifted down while the raven continued circling above seemingly unconcerned. As he was reloading the raven suddenly swooped low over him depositing a large purplish splotch on the front of his cap (the bird had been eating crowberries) he took the cap off and gazed at it in astonishment. He did not think the event either fortuitous or accidental. That experience led him to believe that ravens, in addition to being sharp mentally, also had a sense of humour.
Try this website for some examples http://www.pbs.org/wnet/nature/episodes ... lack/1507/