Avian brains get the study they deserve and are found to be equal in ability to mammalian brains, reports Sandra Blakeslee . (New York Times)
"New Caledonian crows create more complex tools with their beaks and feet. They trim and sculpture twigs to fashion hooks for fetching food. They make spears out of barbed leaves, probing under leaf detritus for prey.
"In a laboratory, when a crow named Betty was given metal wires of various lengths and a four-inch vertical pipe with food at the bottom, she chose a four-inch wire, made a hook and retrieved the food.
"Apes and corvids are highly social. One explanation for intelligence is that it evolved to process and use social information - who is allied with whom, who is related to whom and how to use this information for deception. They also remember.
"Clark nutcrackers can hide up to 30,000 seeds and recover them up to six months later.
"Nutcrackers also hide and steal. If they see another bird watching them as they cache food, they return later, alone, to hide the food again. Some scientists believe this shows a rudimentary theory of mind - understanding that another bird has intentions and beliefs.
"Magpies, at an earlier age than any other creature tested, develop an understanding of the fact that when an object disappears behind a curtain, it has not vanished.
"At a university campus in Japan, carrion crows line up patiently at the curb waiting for a traffic light to turn red. When cars stop, they hop into the crosswalk, place walnuts from nearby trees onto the road and hop back to the curb. After the light changes and cars run over the nuts, the crows wait until it is safe and hop back out for the food.
"Pigeons can memorize up to 725 different visual patterns, and are capable of what looks like deception. Pigeons will pretend to have found a food source, lead other birds to it and then sneak back to the true source.
"Parrots, some researchers report, can converse with humans, invent syntax and teach other parrots what they know. Researchers have claimed that Alex, an African gray, can grasp important aspects of number, color concepts, the difference between presence and absence, and physical properties of objects like their shapes and materials. He can sound out letters the same way a child does."