鸟儿有‘成人’礼吗？

  冬末春初，新搬到墨尔本的一个房子，庭院里有棵树，树上有个鸟窝（请原谅我的无知，我无法给出名字，总之是很普通的种类，绝对不是鹦鹉：）。上图有鸟巢，有心的自己弄明白什么鸟类吧。），惊喜的还发现里面居然有两只小鸟。

  今日早起，发现地上落了只小鸟，黄黄的嘴角，看起来还不会飞的样子。于是我们怀疑，它发生了事故，坠落鸟窝。于是我惊喜的叫来老婆和孩子们一起来看。期间发生有趣的事情，一只鸟爸爸（暂且这么叫，无法分清父母，总之有两只好了）撞向厨房的玻璃，因为我在厨房准备早餐，不时的看几眼，难道它感觉到了威胁？还有鸟妈妈飞下地来陪小鸟，好像还喂食了。我们于是担心，这只小鸟怎么回到鸟巢呢？它还不会飞呢？

树杈上面还站立着另外一只雏鸟，看起来体态稍微丰硕一点。这时我们完全不明白发生了什么？也不知道怎么帮它们？我和老婆说是不是应该打一个什么电话叫人过来把地上的小鸟放回去，否则老鸟们不是着急死了？老婆说，这只是普通的鸟类，应该没有人管？于是我们就出门购物了。

购物回来，往院子观看，小鸟已然不在地上，它站在了树杈上面？中间发生了什么事情，不得而知。或许老鸟们把雏鸟拉上了枝头？或许雏鸟一日之间学会了高飞？总之，它重新回到了枝头，老鸟不断的喂食。也许在安慰受惊吓的心灵。心里想，这下没事了。皆大欢乐！

于是午饭，于是忙七忙八。后来再看的时候，树上没有了雏鸟，老鸟也不知哪里去了。

于是我乱想到，难道今天是鸟儿们的‘成人’礼，过了今日，它们要自己飞行，自己觅食。老鸟今天不过是给它们彻底的锻炼，频繁的喂食也许是老鸟们唯一能为它们离巢做的准备了。所有的一个疑问只是，鸟儿难道一日间就学会了飞翔？

有朝一日，你当展翅飞翔，我送你到这里了！

A Biological Screw in a Beetle’s Leg

The figures above are from Wikipedia.

Nowadays, the Beetle is a kind very popular mini car. There are lot of nuts and screws. Have you ever thought that a real beetle has similar things: screw? Here are results of some scientist.

（This figure is from Science)

Joints on the legs of weevils form a functional screw-and-nut system. Authors: Thomas van de Kamp, Patrik Vagovič, Tilo Baumbach, Alexander Riedel

View article...

Flying in a flock comes at a cost in pigeons

一群鸟以V型队列飞翔，可以减小空气阻力，节约能量消耗。但是以更紧密的别的队列飞行，阻力或能量消耗却要增加。看来packing的方式对能量消耗有很大影响。动物世界真有意思。开一个label "Animal-study'.

The picture is from NATURE

Flying in a flock comes at a cost in pigeons Nature 474, 7352 (2011). doi:10.1038/nature10164 Authors: James R. Usherwood, Marinos Stavrou, John C. Lowe, Kyle Roskilly & Alan M. Wilson Flying birds often form flocks, with social, navigational and anti-predator implications. Further, flying in a flock can result in aerodynamic benefits, thus reducing power requirements, as demonstrated by a reduction in heart rate and wingbeat frequency in pelicans flying in a V-formation. But how general is an aerodynamic power reduction due to group-flight? V-formation flocks are limited to moderately steady flight in relatively large birds, and may represent a special case. What are the aerodynamic consequences of flying in the more usual 'cluster' flock? Here we use data from innovative back-mounted Global Positioning System (GPS) and 6-degrees-of-freedom inertial sensors to show that pigeons (1) maintain powered, banked turns like aircraft, imposing dorsal accelerations of up to 2g, effectively doubling body weight and quadrupling induced power requirements; (2) increase flap frequency with increases in all conventional aerodynamic power requirements; and (3) increase flap frequency when flying near, particularly behind, other birds. Therefore, unlike V-formation pelicans, pigeons do not gain an aerodynamic advantage from flying in a flock. Indeed, the increased flap frequency, whether due to direct aerodynamic interactions or requirements for increased stability or control, suggests a considerable energetic cost to flight in a tight cluster flock.

View article...


Aerodynamics: The cost of flight in flocks
Nature 474, 7352 (2011). doi:10.1038/474458a
Authors: Geoffrey Spedding
There are well-known aerodynamic and energetic benefits to flying in an orderly formation. By contrast, it seems that the flocking flight seen in pigeons is metabolically expensive. So why do they do it?

动物依靠地磁的行为研究

Nature 464, 1140-1142 (22 April 2010) | doi:10.1038/4641140a; Published online 21 April 2010

Q&A: Animal behaviour: Magnetic-field perception

Kenneth J. Lohmann¹

of page

Abstract

The ability to perceive Earth's magnetic field, which at one time was dismissed as a physical impossibility, is now known to exist in diverse animals. The receptors for the magnetic sense remain elusive. But it seems that at least two underlying mechanisms exist — sometimes in the same organism.