【英语时差8,16】鸟类冰冷的脚和温暖的翅膀

 The world can be divided into two kinds of people: the ones who see a one legged seagull and feel a twinge of sympathy, and the ones who assume the other leg is still there but mysteriously hidden.   Who's right?

Actually, most birds you see standing¹ on only one leg are doing an impressive balancing act while tucking² the second leg into their feathers. This is much easier to recognize in large birds, such as flamingoes, but the behavior itself is common to most birds. So, the real question is: why do they do that?

The answer is that birds use their feet for temperature regulation. In most birds the legs and feet are unfeathered, and thus lose heat very quickly -- the same way your exposed hands get cold in winter faster than your clothing-covered torso. That makes the bare feet great conductors: when the bird's overall body temperature is too high, it can cool off by standing on both legs and letting the wind carry away heat. When the temperature drops too low, it can pull one leg up and lose less heat. Finally, it can sit down and cover all the bases.

Many birds are able to control the amount of blood flow through their legs, which increases their ability to regulate³ temperature. The only danger comes in standing around on a cold day: with one foot tucked⁴ up and blood flow greatly reduced to the other, there is a possibility that the exposed leg will freeze. This can be countered by staying in a nest or, in aquatic⁵ birds, by going into the water. As long as the water is in a liquid state, the bird legs floating in it can't freeze.  

1 standing   

n.持续，地位；adj.永久的，不动的，直立的，不流动的

参考例句：

• After the earthquake only a few houses were left standing.地震过后只有几幢房屋还立着。
• They're standing out against any change in the law.他们坚决反对对法律做任何修改。

2 tucking   

手压实（砂型）

参考例句：

• He crouched, tucking his knees under his chin. 他蜷曲着，把两个膝盖缩拢在颚下。
• I can assure you that we have every chance of tucking his ass into jail. 我敢向你担保，我们完全有把握将这头蠢驴塞进监狱。

3 regulate   

vt.管理，控制，调节，调校，调整

参考例句：

• This system can regulate the temperature of the room.这种系统能调节室内温度。
• They regulate the flow of water by the sluice gate.他们用水闸门控制水的流量。

4 tucked   

塞进( tuck的过去式和过去分词 )； 翻折； 盖住； 卷起

参考例句：

• She tucked up her skirt and waded into the river. 她撩起裙子蹚水走进河里。
• She tucked a loose strand of hair behind her ears. 她把一缕散发夹到了耳后。

5 aquatic   

adj.水生的，水栖的

参考例句：

• Aquatic sports include swimming and rowing.水上运动包括游泳和划船。
• We visited an aquatic city in Italy.我们在意大利访问过一个水上城市。