Jays Plan Ahead, Study Shows
The Corvidae family of birds, whose members include crows, ravens and jays, has always had a reputation for braininess. New research adds to the evidence it is well-deserved.
C.R. Raby, Nicola S. Clayton and their colleagues at the University of Cambridge, England, ran two experiments to determine whether scrub-jays could make plans to alleviate hunger in specific situations. They described the results Feb. 22 in the journal Nature.
The researchers had the birds fast overnight. In the morning, each bird was placed alone into one of the two end "rooms" of a three-compartment cage. In one room, the bird got food -- in this case, ground-up pine nuts. In the other room, it got no food. After two hours, the bird had access to all three rooms.
Researchers did this for six days, alternating the birds from the "breakfast" to the "no-breakfast" rooms. On the seventh night, they put a "cacheable" food (whole pine nuts) in the middle compartment and opened the doors to all three rooms. The jays saved more food in the room that they had learned was the no-breakfast room than in the breakfast one -- apparently anticipating what would happen the next day.
In another experiment, the researchers put food in the two end rooms, but of different types -- dog kibble in one and peanuts in the other. After two hours of morning confinement with only one food, the birds were allowed access to all three rooms.
On the seventh night, containers of both foods were put in the middle compartment. The birds cached some of both foods in each of the end rooms but saved more kibble in the peanut room and more peanuts in the kibble room. The scientists believe this shows that the birds preferred having a choice of food and that they did what was necessary to ensure each room had a choice.
The experiments reveal a level of planning previously seen only in primates. Clayton, one of the authors, theorized that some forms of complex cognition may have evolved separately in the lineages leading to the two types of animals.
-- David Brown
Older Eyewitnesses Less Reliable
Older adults are less reliable eyewitnesses than younger people, a new study has found.
Researchers at the University of Virginia arrived at that conclusion after running an experiment in which participants -- some ages 60 to 80, others college-age -- were shown a five-minute video reenactment of a burglary and car chase. Then they answered 24 yes-or-no questions about what they had seen. Eight questions referred to details not in the video, erroneously suggesting, for example, that a gun had been present.