Not all birds sing, but those that do—some several thousand species—do it a lot.
Iris Adam, a scientist at the University of Southern Denmark says, birds have “a drive to sing”. This means hours every day for some species, and that takes a lot of energy. However, singing can be dangerous. “As soon as you sing, you show yourself, for example, where you are and that you even exist—all of that immediately is out in the open for predators (捕食性动物) , for everybody,” she says.
In a new study published in the journal Nature Communications, Adam and her colleagues offer a new explanation for why birds take that risk and whether the muscles (肌肉) that produce birdsong require daily exercise. Adam designed an experiment on zebra finches—little Australian songbirds. Her experiment included keeping male birds in the dark to sever the connection between their brains and-their singing muscles, which prevented them from singing.
After a week, the birds’ singing muscles lost half of their strength. Three weeks later, they were back to the same level when they were juveniles (幼鸟) and never had sung before. When Adam played one of the male’s songs for: a group of female birds, six out of nine preferred the song that came from a male who had been using his singing muscles daily.
Adam’s conclusion (结论) is that songbirds need to exercise their singing muscles to produce top-performance song. If they don’t sing, they lose performance, and their songs get less attractive to females, which is bad.
“What they stress is that you need a lot of practice to improve what you’re doing,” says Ana Amador, a scientist at the University of Buenos Aires. It’s a good rule to live by, whether you’re a bird or a human—practice makes perfect, at least when it comes to singing one’s heart out.
32. Why can singing be dangerous for birds?
A.They can drive predators to sing. | B.They never protect their areas. |
C.Their singing can attract predators. | D.Singing does damage to their muscles. |
33. What does the underlined word “sever” probably mean in paragraph 3?
A.Remember. | B.End. | C.Risk. | D.Keep. |
34. What do we know about Adam’s experiment?
A.It mainly focused on male birds and juveniles. |
B.It aimed to protect zebra finches from possible risks. |
C.It strengthened birds’ singing muscles in four weeks. |
D.It proved exercising singing muscles matters to birds. |
35. Which is the most suitable title for the text?
A.Iris Adam’s work is a big success | B.Singing can be dangerous for birds |
C.Birds sing to keep muscles in shape | D.Birds and human beings need practice |