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 BrownOlder Eyewitnesses Less ReliableOlder 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.
The older and younger participants were about as likely to assert they had seen something in the video that merely had been suggested in the follow-up questions. But older people were much more likely to be confident that they had the details right when in fact they were wrong.
The findings, taken together with earlier research showing that older adults are more likely than younger people to misremember the details of events, suggest that the aging of the population could have implications for how well the judicial system works.
"Given that older adults will constitute an increasing proportion of the U.S. population, there may be a corresponding increase in the occurrence of wrongful convictions based on the testimony of highly confident but mistaken witnesses," said lead author Chad Dodson, an assistant professor of psychology at U-Va.
The study was in the journal Psychonomic Bulletin & Review.
-- Christopher LeeWhite Marlin Even Less Plentiful The already-depleted population of the popular sport fish white marlin may be in even worse shape than scientists had thought, according to a study published last month in the journal Bulletin of Marine Science. For years, fishermen have been catching a similar-looking species that researchers now identify as the roundscale spearfish, creating the mistaken impression that white marlin were more plentiful. The roundscale spearfish is almost identical but has rounded scales and slightly different fins.
"This is a case of mistaken identity," said Mahmood Shivji, lead author and director of Guy Harvey Research Institute at Nova Southeastern University.
Environmental advocates have tried to list the white marlin as an endangered species because its population has fallen 88 percent below the level considered healthy, but they have not won federal protection for the species.
Shivji, who conducted a DNA analysis of several species of Atlantic billfish, determined that 16 fish caught by fishermen in the northwest Atlantic were roundscale spearfish, not marlin.
"The question is what proportion of 'white marlin' are actually roundscale spearfish," Shivji said Friday. "That's just a question that needs to be urgently addressed."
-- Juliet Eilperin