The fox turned to jump at the juvenile, whereupon the adult, positioned 150 yards aloft, dived silently, striking the quarry in the shoulder blades and knocking it down. The fox, evidently trying to reach cover some distance away, got up and ran again. The tandem strike was repeated. On the fourth attack, the adult eagle sank its talons into the fox and held on. The younger one joined the attack, and after a fearful struggle, the fox was dead.

Does this mean the eagle is smarter than the fox? Not likely, said Dr. Ellis, since "the fox will run the same game on him." In Montana, he said, he has seen foxes distract a golden eagle eating its meal in an attempt to steal the food. If the eagle had simply held its ground, it could have eaten the meal and also killed a fox if it had attacked. Instead, it chased one fox away, creating an opening for the theft. "It's real clear that the fox is smarter," he said.

On the other hand, raptor teamwork appears to signify a higher order of behavior than the cooperative hunting of spiders and ants, in whom it is genetically preprogrammed.

Dr. Ellis has spent months observing the behavior of golden eagles, and he says, "It's hard for me to imagine that they hadn't learned from their mistakes early on and were profiting from that learning, which means they're intelligent rather than practicing something innate." All of this, he says, is grist for further investigation -- a daunting task, given the difficulty of studying raptors. Ploys by Eagles

Many other instances of coordinated hunting by pairs of raptors have also been reported. In southern Africa, two black eagles were observed to approach a colony of cape vultures. While the leading eagle flew over the nest and the adult vultures tried to drive it away, the trailing eagle glided in from behind and snatched a vulture chick in each foot.

In a similar ploy, a crowned eagle in South Africa was seen to leave its perch and dive across a valley toward some trees where vervet monkeys lived. It swooped low over the trees and zoomed up and away without pausing. When a monkey climbed out of cover onto a topmost branch to watch the eagle fly off, a second eagle swooped down, grabbing the monkey from behind. Both eagles then flew off together, presumably to feast.

Crowned eagles have also teamed up successfully on the bushbuck, which weighs as much as small-to-average adult human and has more than four times the mass of the eagle.