Some birds are inside decorators, placing big, showy feathers in their nests. But rather than beautifying their homes, these birds may be trying to scare nest-stealing neighbors.
Birds sometimes weave feathers into their nests to provide insulation (隔绝). But behavioral ecologists Karen Wiebe and Tore Slagsvold also saw birds placing large feathers on the surfaces of nests. Those feathers wouldn’t help with warmth. The researchers wondered whether the birds might be using the decorations to send a message.
For birds that nest in holes, competition for nests can be really fierce. Birds scream and fight, sometimes killing an opponent. But these holes can also hide danger. Eagles or other predators may be hiding inside. If a nest contains feathers or other remains, it might be evidence that a predator had been there. Those holes might not be desirable.
During spring, when nest competition is the fiercest, the researchers set up pairs of nesting boxes. One box contained white feathers. The other either contained no feathers or black feathers. Inside the boxes, black feathers were more difficult to see than white ones. Using video cameras, the researchers spied on how tree swallows, blue tits, and pied flycatchers reacted to the boxes. They watched how long birds waited to explore a nest box. When birds took longer to enter, that suggested the birds were scared.
Birds of all three species hesitated to enter boxes with white feathers. But when feathers were in front of a nest, birds jumped right up and grabbed them. That suggested that birds weren’t afraid of the feathers themselves.
“It was really interesting to discover that birds were using a trick to help them keep their nests,” Wiebe says. “When a bird leaves its nest to search for food, it opens the door for a nest stealer. But if it can buy a little time by scaring away intruders (不速之客) with these feathers, then it has a better chance of coming back in time to defend its nest site.”
8. Why do birds cover the surfaces of their nests with big feathers?
A.To keep warm. | B.To attract mates. |
C.To scare off intruders. | D.To hide from predators. |
9. What did the researchers find?
A.Feathers alone fail to frighten birds. |
B.Holes with black feathers scare birds most. |
C.Most birds are hesitant to get into white boxes. |
D.Birds like feathers similar to those of their own. |
10. What can we infer about birds from Wiebe’s words?
A.They are poor at using tricks. |
B.They use feathers to play catch. |
C.They seek food near their nests. |
D.They may be aware of nest stealers. |
11. What can be the best title for the text?
A.Birds protect their food from predators cleverly |
B.Birds attach importance to decorating their nests |
C.Birds decorate nests to scare off stealers |
D.Birds identify danger by feather colors |