The birds were put in cages that were divided into three parts. In the evening they were kept in the middle section, and fed powdered pine nuts that they couldn't store. In the morning, they were kept either in the 'breakfast room', where they were given food, or went hungry in the 'no-breakfast room'.
After getting used to this set-up, the jays were given whole pine nuts in the evening, which they could bury in trays of sand. The jays put three times as many in the no-breakfast room than in the breakfast room, so that they wouldn't go hungry in the morning.
In another experiment, the jays got breakfast in both rooms. However, their breakfast comprised whole peanuts in one room, and dried dog food in the other. When given both foods in the evening, the birds stored each food in the room where it would be lacking the next morning.
No other animals outside humans have been shown able to plan actions based on how they will feel in the future