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为什么鸟睡着了也不会从树上掉下来?

How Do Birds Stop From Falling Off Branches While They Sleep?

In the video today we are answering a viewer question
在今天的视频中 我们回答一个观众的问题
because Abi W. asks us why don’t birds fall off branches when they sleep?
因为Abi W.问为什么鸟睡着了也不会从树上掉下来
Everyone needs sleep, but for many birds
每个人都需要睡眠 鸟儿也不例外
by necessity this has to happen while perched
但它们必须得栖息在树枝上
on a branch or other place that must be gripped.
或者其他能抓牢的地方
Anyone who has ever fallen asleep reading and found her book on the floor
读书的时候睡着了 醒来发现书在地板上的人都知道
knows how difficult it can be to hold onto something while snoozing.
要在打盹的时候抓住东西是多么的困难
So how do perching birds do it?
那么树栖鸟类是如何做到的呢?
Powered by tendons, the feet of grasping birds (think perching birds and raptors)
抓握型鸟类(如树栖鸟类和猛禽)
have a pair of them in the back,
脚后有一对跟腱
flexor digitorum longus and flexor halluciss longus,
趾长屈肌和长屈姆趾肌
which are connected to deep flexor muscles in the leg.
与腿部深层屈肌相连
The digitorum branches and works the three toes in the front,
趾分支并使前面的三个脚趾活动
while the hallucis works the back toe, known as the hallux.
而拇趾作用于脚后趾 也就是大家所熟知的后趾
Both stretch over the ankle,
两者都伸展到脚踝
and when the bird lands and the ankle bends,
当鸟落地时 脚踝弯曲
this forces both tendons to automatically pull, thus clenching the toes closed.
迫使两个肌腱自动拉伸 从而握紧脚趾
As long as the ankle is bent,
只要脚踝弯曲
the tendons and toes are locked into place.
肌腱和脚趾就会锁在此处
For perching birds, this results in a dependable grip
对栖息鸟类来说 这就是一个可靠的抓地力
that lasts even when sleeping.
即使睡着了也能稳稳地抓握
Raptors use this automatic response for another purpose as well – grasping prey.
猛禽也能利用这一自然反应抓捕猎物
As the raptor approaches its victim, its legs are outstretched,
当猛禽接近猎物时 腿部是张开的
but when it lands, its ankles bend,
但当它落地时 脚踝弯曲
pulling the tendons and closing the toes – resulting
肌腱拉伸 脚趾合拢
in a firm grip on its dinner.
就能牢牢抓住自己的大餐
Even in flight, as long as the bird’s legs are bent,
哪怕是在飞行中 只要鸟的腿弯曲
the tendons and toes remain locked on the prey.
肌腱和脚趾仍然能锁定猎物
Not all birds have this feature,
但并非所有的鸟类都有此特征
and for those forced to sleep on the ground, some have developed
对于那些不得不睡在地上的鸟儿来说
another adaptation to slumber safely – sleeping with one eye open.
有些已经进化出另外一种安全睡眠模式:睁着一只眼睡觉
Known as unihemispheric slow-wave sleep, some birds,
也就是单半球慢波睡眠
like mallard ducks, can keep half of
某些鸟类比如绿头鸭
their brain (and its corresponding eye) alert while allowing the other half to take a break.
能让与眼睛相关的那半部分大脑保持警觉 而让另一半大脑休息
With the mallards, they often rest in a row,
绿头鸭经常排成一排休息
with the ducks on the ends closing the eye
而排在两端的鸭子
next to their neighbors, but keeping the eye facing potential danger open.
会闭上靠近邻近伙伴的那只眼睛 另一只眼睛睁开保持警惕
Interestingly, this seems birds can control this function in during times of rest safety,
有趣的是 似乎鸟类在安全休息时能控制这项技能
they are able to rest their entire brains.
让整个大脑得以休息
Like the mallard ducks,
与绿头鸭相似
dolphins and whales often sleep with one eye open
海豚和鲸鱼经常睁着一只眼睛睡觉
The ability to stay partially conscious also allows
保持部分清醒的能力也能让它们
them to continue to get air while sleeping.
在睡觉的时候继续换气
How dolphins handle this is to put one half of their brain to sleep,
海豚是这样做的:让它们一半的大脑休眠
while the other halfis still conscious and functioning.
而另一半大脑保持清醒警觉
They then alternate which side is sleeping periodically.
之后它们会定期地变换着进行休眠
They stay in this state for approximately eight hours a day.
每天差不多八小时它们都要保持这种状态
Doing this allows them to be
如此能让它们
conscious enough to control their breathing and periodically
保持足够清醒地去控制呼吸
swim to the surface and get air,
定期游到海面上换气
while still giving their brain the rest it needs.
同时给予大脑必要的休息
It also allows them to stay alert for potential predators some are how to does it.
也能让它们对潜在的捕食者有所防备
So I really hope you found that short video interesting, if you did
真心希望你们觉得这个短片很有趣
give us a thumbs up below.
是的话 就在下面点个赞吧
Why not and also subscribe and hit that bell if you actually want to
如果你想在我们上新视频的第一时间就知道的话
find out when we put out a new video.
何不在铃铛那里点击下订阅呢?
Also if you’re looking for more from the another channel called Highlight History,
此外 如果你想了解更多Highlight History频道的内容
which I’m linking to below, so go check that out if you fancy it
可以点击下面的链接 喜欢的话就去看看吧
And as always, thank you for watching!
一如既往 谢谢你的观看

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视频概述

看书的时候打盹,书会掉在地板上;鸟在树上睡着了,怎么都不见从树上掉下来?这是为什么,为什么,为什么呢……

听录译者

收集自网络

翻译译者

长安小盆友

审核员

审核员DY

视频来源

https://www.youtube.com/watch?v=Kho-V-vqZBQ

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