【英语时差8,16】鸟类中不同的行走方式

 Last time we were thinking about why some birds hop¹ and other birds walk. We decided² that you can't make any blanket statements about this, because there will always be exceptions. But in general it's true that larger birds are more likely to walk and smaller birds to hop, just because of the amount of energy it takes. But there's more to it than that. Ornithologists are actually very interested in bird legs and feet. The differences between different kind of legs are used in bird classification. For example, what we commonly call "songbirds"--cardinals, wrens³, mockingbirds, warblers--are also called "perching birds." They have specialized⁵ structures in their feet that include three toes pointing forward and one more called the "hallux" that points back. That three-and-one design is excellent for holding on to branches, which is an important skill to possess if you are a bird. Okay, so far so good. But now, what does that kind of foot make more difficult? You got it--a foot with a conspicuous⁶ hallux toe won't be very good at walking. Some birds manage it, and there are different kinds of hallux toes that make it easier or harder. But to move around with feet like that, sometimes you just might be better off hopping⁷. So, evolution has to make a choice. Is it better to perch⁴ safely on branches or walk comfortably on the ground? Do I catch food with my feet or my beak⁸? And so on. The end result can be birds with different kinds of feet, and different kinds of walks.

1 hop   

n.单脚跳，跳跃；vi.单脚跳，跳跃；着手做某事；vt.跳跃，跃过

参考例句：

• The children had a competition to see who could hop the fastest.孩子们举行比赛，看谁单足跳跃最快。
• How long can you hop on your right foot?你用右脚能跳多远？

2 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。

3 wrens   

n.鹪鹩( wren的名词复数 )

参考例句：

• Other songbirds, such as wrens, have hundreds of songs. 有的鸣鸟，例如鹪鹩，会唱几百只歌。 来自辞典例句

4 perch   

n.栖木，高位，杆；v.栖息，就位，位于

参考例句：

• The bird took its perch.鸟停歇在栖木上。
• Little birds perch themselves on the branches.小鸟儿栖歇在树枝上。

5 specialized   

adj.专门的，专业化的

参考例句：

• There are many specialized agencies in the United Nations.联合国有许多专门机构。
• These tools are very specialized.这些是专用工具。

6 conspicuous   

adj.明眼的，惹人注目的；炫耀的，摆阔气的

参考例句：

• It is conspicuous that smoking is harmful to health.很明显，抽烟对健康有害。
• Its colouring makes it highly conspicuous.它的色彩使它非常惹人注目。

7 hopping   

n. 跳跃 动词hop的现在分词形式

参考例句：

• The clubs in town are really hopping. 城里的俱乐部真够热闹的。
• I'm hopping over to Paris for the weekend. 我要去巴黎度周末。

8 beak   

n.鸟嘴，茶壶嘴，钩形鼻

参考例句：

• The bird had a worm in its beak.鸟儿嘴里叼着一条虫。
• This bird employs its beak as a weapon.这种鸟用嘴作武器。