http://www.livescience.com/17213-ravens-gestures-animal-communication.html

Many animals have intelligence features which our species has entirely overlooked. I have had experiences with corvids in the wild that make science fiction look tame in comparison…

“It reminded me of my childhood, when my twin brother and I were still little and one of us suddenly regained a favorite toy, which existence both of us had forgotten for a little while. This toy suddenly became the center of interest, fun and competition. Similar things happen, when ravens play with each other and regain objects.”