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Author Topic: How Do Kestrels Hover ?  (Read 4933 times)

Offline neilep

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How Do Kestrels Hover ?
« on: 22/08/2007 13:21:16 »
Dear Peeps,

This is a Kestrel:



I luff em !...see them all the time hovering away ready to dive in and grab a take-a-way !

But how do Kestrels hover ?.
...I don't see the Robin that frequents my garden hover !

Does it have an updraft mechanism like a Hovercraft ?....or does it work like those hover mowers ?

I don't know.....but I reckon someone here does.


 

Offline DoctorBeaver

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How Do Kestrels Hover ?
« Reply #1 on: 22/08/2007 13:58:15 »
They use headwinds so that relative to the air they are flying forwards, not hovering.
 

another_someone

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How Do Kestrels Hover ?
« Reply #2 on: 22/08/2007 16:39:14 »
Headwinds or thermals - i.e. they are either flying forward into a wind, or they are falling through an upward flowing thermal.

Hummingbirds, on the other hand, do hover in a true sense, but they have extremely fast wingbeats.
 

Offline neilep

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How Do Kestrels Hover ?
« Reply #3 on: 22/08/2007 17:36:07 »
THANK YOU DOCTORBEAVER & GEORGE,

So, how come I don't see other birds falling into headwinds/thermals ?

You are most kind.

« Last Edit: 22/08/2007 18:49:14 by neilep »
 

another_someone

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How Do Kestrels Hover ?
« Reply #4 on: 22/08/2007 17:57:52 »
You do, but it depends on the bird.

When a bird is using thermals, or flying into headwinds in the manner of a kestrel, it is basically gliding, and so to do it efficiently, it must be a good glider, which means it needs to have a high aspect ratio wing (i.e. a very long wingspan in relation to its length from front to back).  This is exactly the opposite configuration that would be desired to create high manoeuvrability or rapid take-off (for which you want short wings that can beat fast).

Any bird can fly into wind, and can appear to hover in relation to the ground, but a bird with a high aspect ratio can do so with less wind than a bird with a lower aspect ratio wing.  In gale force conditions, many birds can fly into wind and appear to hover.
 

Offline neilep

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How Do Kestrels Hover ?
« Reply #5 on: 22/08/2007 18:51:47 »
You do, but it depends on the bird.

When a bird is using thermals, or flying into headwinds in the manner of a kestrel, it is basically gliding, and so to do it efficiently, it must be a good glider, which means it needs to have a high aspect ratio wing (i.e. a very long wingspan in relation to its length from front to back).  This is exactly the opposite configuration that would be desired to create high manoeuvrability or rapid take-off (for which you want short wings that can beat fast).

Any bird can fly into wind, and can appear to hover in relation to the ground, but a bird with a high aspect ratio can do so with less wind than a bird with a lower aspect ratio wing.  In gale force conditions, many birds can fly into wind and appear to hover.

THANK YOU GEORGE,

This is what I was getting at...it must be ' bird dependent' as the Kestrel seems to do it by design !

Notice the tail...I wonder if this is prerequisite for the Kestrel to be able to do what it does so well.

Thanks again
 

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How Do Kestrels Hover ?
« Reply #5 on: 22/08/2007 18:51:47 »

 

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