【英语时差8,16】鸟能识别人类吗？

Do Birds Recognize Humans? How dumb, or smart, are birds? Calling someone a birdbrain is usually meant as an insult. But many birds are quite clever. Take, for example, the mockingbird. To you and me, one mockingbird might look pretty much like any other. But from the birds’ perspective, the same isn’t true of humans. Mockingbirds can tell one person from another with great skill, especially when that person poses¹ a threat. In one experiment, scientists had volunteers approached and touched mockingbird nests once a day for four days. By the second day, the birds began their warning calls and attack runs sooner than they had the day before. By the fourth day, the birds appeared to be able to spot the human intruders as soon as they began to approach the nests. On the fifth, day, however, a new person approached and touched the birds’ nests. And the birds were slower to react. So in other words, the birds weren’t simply protecting their nests with the same ferocity no matter who approached. They quickly recognized repeat intruders and were quick to target them. Because the new intruder wasn’t familiar, the birds took longer to size him up. Mockingbirds might not be the only bird species² to distinguish³ between people. Other species that have adapted to human environments might be good people spotters, too. In fact, this ability might be part of what allows some birds to thrive in urban environments.

1 poses   

使摆姿势( pose的第三人称单数 )； 以…身份出现； 招摇； 炫耀

参考例句：

• This poses a threat to agriculture and the food chain, and consequently to human health. 这会对农业和食物链造成威胁，由此而危及人的健康。
• The high cost of oil poses serious problems for industry. 昂贵的石油价格给工业造成了严重困难。

2 species   

n.物种，种群

参考例句：

• Are we the only thinking species in the whole of creation?我们是万物中惟一有思想的物种吗？
• This species of bird now exists only in Africa.这种鸟现在只存在于非洲。

3 distinguish   

vt.区别，辩明，识别，辨认出；vi.区别，辨别，识别

参考例句：

• It is not easy to distinguish cultured pearls from genuine pearls.辨别真正的珍珠与养殖的珍珠不容易。
• Some people find it difficult to distinguish right from wrong.一些人认为很难辨对与错。