Intelligence? It's for the birds.

Bird brains seem to be smarter these days. Scientists are finding hints of a higher level of intelligence than expected as they look more closely at our avian friends.

The findings raise anew questions of what we consider to be thinking and how thinking works.

Take, for example, the skill of getting along in your group. Monkeys do it. Humans are masters of it and consider it a hallmark of their intelligence. But who would have thought birds have a clue? Yet Clémentine Vignal at the University of Paris and colleagues have found a remarkable social sensitivity among zebra finches.

In July, they reported in Nature that male finches know when, and when not, to pay careful attention to their mates depending on the social context. First they determined that a male can clearly identify his mate's call, a skill some scientists had doubted. Then they found that the male didn't pay special attention to the call unless there were one or more mated pairs of finches nearby. Somehow, the presence of other mated couples set up a social situation in which it was "proper" to pay more attention to his own mate. Shades of the neighborhood picnic?

The behavior "suggests for the first time that a nonprimate may be able to assess the social relationships between other animals of its own species, an ability thought to be a mark of intelligence," says Christopher Sturdy at the University of Alberta in Canada, commenting on the study.

Pinyon jays provide further evidence. In a more recent Nature paper, Guillermo Paz-y-Miño of the University of Nebraska in Lincoln and colleagues report that these jays can sort out social status in a group without fighting. To figure out who is who by watching how individuals behave toward each other is a high-level skill. Psychologists call it transitive reasoning.

Scientists did not expect the birds to be that bright.

The jays' behavior "implies a more complex set of cognitive skills" than even the zebra finch study shows, writes Sara Shettleworth, with Canada's University of Toronto, in a companion article.

Together, the findings add significantly to the growing evidence of what could be called avian intelligence. Some birds such as ravens use simple tools. Others store thousands of seeds in thousands of caches during a season and then remember where most of those caches are. Laboratory experiments have shown that real memory - not just aimless poking about - is involved.

But the ability by birds to show some social graces suggests that they are incorporating a higher order of mental ability than researchers previously thought.

There could be enough advantages in such ability for evolution to favor birds that form social groups.

Certainly it's better in the long run for group members to know where they rank in the pecking order without having to constantly peck each other to find out.

Rather than an overall leap in avian intelligence, the findings point to specialized mental abilities for individual species. Dr. Shettleworth points out that evolution is likely to favor the emergence of such abilities in different species depending on the circumstances in which the individual species evolve.

Nevertheless, the research gives new meaning to the term "bird brain." Learning exactly what that meaning is should shed light on animal intelligence in general.