Acorn woodpeckers (橡树啄木鸟), which live along the west coast and in the southwest of North America, are highly socialized birds, a study showed recently.
In the acorn woodpecker family, it’s a group effort to raise the young. Each of the acorn woodpecker family consists of as many as seven co-breeding (共育) males and four joint-nesting females, living with nest helpers who are typically their babies from previous years. The helpers don’t breed, but stick around for five to six years to help raise their half-siblings.
Every fall acorn woodpeckers store thousands of acorns in holes drilled into dead trees in preparation for winter. The entire group contributes to a central granary (粮仓), defending it against squirrels and other woodpeckers. But the cooperation may end and great noise and confusion may start when a family loses either all its breeding males or females to old age or enemies like hawks. That leads to a good opportunity for the helpers to grab newly vacant spots with acorns (橡树果) in main habitat.
The news travels fast. The nearby woodpecker groups rush to the site and fight against each other. Over 40 of the “warrior” birds, in coalitions (联盟) of three or four, spend over 10 hours a day over multiple days in battles until one collective wins. “You can see birds with eyes removed out, with blood on their feathers — they fall to the ground holding each other’s legs when they’re fighting,” said Sahas Barve, the lead author of the study. These battles also draw woodpecker audience, who leave their own territories unattended. The researchers recorded some audience travel over two miles and spend an hour a day just observing the fights. “The speed at which such information is communicated among populations has always struck me,” said Reed Bowman.
The scientists said the battles reveal a lot about animals’ social behavior. Sahas Barve said, “We often think of birds as not very intelligent animals, but we are discovering that we aren’t the only super-curious social animal out there. And birds are doing that all the time. Social complexity is something that’s evolved multiple times in the animal kingdom, and we are just one of them.”
【小题1】What does the second paragraph mainly focus on?| A．The loose social networks of acorn woodpeckers. |
| B．The tough living conditions of acorn woodpeckers. |
| C．The great contribution of nest helpers to their family. |
| D．The cooperative breeding system of acorn woodpeckers. |
| A．To survive the tough winter. | B．To fight for their own territory. |
| C．To select the most powerful leader. | D．To rid their granary of noise and confusion. |
| A．They are long and fierce. | B．Their fighters increase each day. |
| C．They will be settled by compromise. | D．They will cause many deaths of the audience. |
| A．Human beings have great curiosity about the outside world. |
| B．Social complexity is unique to human beings. |
| C．Birds are much smarter than we thought. |
| D．The evolution of animals is quite slow. |
