http://www.japantimes.co.jp/text/nn20111206a4.html
Memory test: A crow selects a sealed container holding food during an experiment to test the bird's long-term memory. SHOEI SUGITA / KYODO PHOTO
MAEBASHI, Gunma Pref. — Researchers have recently found that crows possess a long-term memory that allows them to remember colors for at least a year, a talent they use to successfully select containers containing food in experiments based on color cues after extended intervals.
"It is not easy even for human beings to remember visual color information for a year. Crows may be even better than human beings in a certain aspect of memory," said Shoei Sugita, a professor of animal morphology at Utsunomiya University who led the joint research with Chubu Electric Power Co.
The finding came as part of a study that Chubu Electric, troubled by problems presented by crows' nests on power line towers, commissioned in 2008.
In the tests, the researchers prepared two containers in a cage, showing 24 jungle crows two cups covered with colored paper — one with a red and green lid that contained food and the other with a yellow and blue lid that did not.