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#21
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Uri Saovray wrote:
Yes, but could you hear their varios beep? Don't be silly, have you ever seen a bird carrying batteries? Rgds, Derrick Steed |
#22
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Take a look at Darryl Stinton's book "The design of the aeroplane" - there
is a captioned picture in the front of it showing a gull (an Albatross, I think) soaring a cliff in front of the camera. The caption points out aerodynamic function of various parts of the birds anatomy in a most enlightening manner! I don't have the book in my possession right now (I loaned it to the CFI of a local club, I should get it back I suppose) or I would post the picture and it's caption. Rgds, Derrick Steed On 4 Jul 2004 20:39:04 GMT, Andy Blackburn wrote: Any bird experts out there? While still in India I met a German lass who was an ornithologist and in India do a PhD on vultures. Naturally, I asked her about their flight performance. She just looked at me like I was a dinosaur: she knew nothing and cared less about their flight performance or operating methods. All she was interested in was stuff like population densities, diet and their behaviour when not flying. I found her attitude most odd. That was 25 years ago so things, hopefully, might have improved in ornithological circles. So, pick your bird expert carefully before asking about how birds fly. BTW, a good book about flight in general (literally from insects to 747s) is 'The Simple Science Of Flight' by Henk Tennekes. It won't tell you how raptors find lift but has a good analysis of how flying creatures size and weight affect their way of making a living and vice versa. Besides, any book on flight that can sensibly show everything from a Monarch Butterfly to a 747-400 on the same graph can't be all bad! |
#24
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Darwin would say the ones that didn't thermal too well didn't
survive, didn't reproduce, and simply missed out on some good airtime for generations to follow. The birds that acquired the insight to locate updrafts gained the same advantage we seek: xc distance. Soaring birds are usually larger than others, maybe good thermaling skills means better meals. They still need to survive winters with fewer, weaker thermals by other means. gill www.gillcouto.com Uri Saovray wrote: Does anyone have an idea of how the birds know where to thermal? Do they have a vario? Where is it? Where is its capacity? Assuming they breath while thermalling, then I doubt they use their lungs as capacity... or maybe they stop and sense the air coming out their noses. Just wondering... Uri 4XGJC |
#25
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I'm also convinced that birds soar for pleasure as well as because they might have to Earlier this year sitting in my garden on a hot windless day, I watched a Buzzard pick up a thermal over a small local wood and climb until it was a speck in the sky. It then closed its wings and dived at great speed until it was about fifty feet above the ground, pulled out and then proceeded to climb again. It repeated the climb, dive, climb manoeuvre three times before I went indoors. Surely that could not have been for anything other than pleasure ? DB |
#26
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More likely it was stooping for prey which moved to
cover or perhaps a mating display. (Showing off, nothing new there then :-)) Most birds of prey (owls excepted) use thermals as a source of free energy to be able to observe prey. Captive birds of prey will not fly if they are 'not hungry', in need of food and if they eat and become over a certain weight flight becomes difficult or even impossible for them. (Anyone know the maximum all up weight of a swallow) At 09:12 05 July 2004, Silent Flyer wrote: I'm also convinced that birds soar for pleasure as well as because they might have to Earlier this year sitting in my garden on a hot windless day, I watched a Buzzard pick up a thermal over a small local wood and climb until it was a speck in the sky. It then closed its wings and dived at great speed until it was about fifty feet above the ground, pulled out and then proceeded to climb again. It repeated the climb, dive, climb manoeuvre three times before I went indoors. Surely that could not have been for anything other than pleasure ? DB |
#27
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"Don Johnstone" wrote in More likely it was stooping for prey which moved to cover or perhaps a mating display. (Showing off, nothing new there then :-)) As Buzzards are carrion eaters I doubt if it was chasing it very far. John |
#28
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Sorry to be pedantic, but not exclusively, Buzzards
can and do take live coneys and rats, I have witnessed them doing so. Are you sure you are not confusing them with Kites which are almost exclusively carrion eaters. At 12:36 05 July 2004, J.M. Farrington wrote: 'Don Johnstone' wrote in More likely it was stooping for prey which moved to cover or perhaps a mating display. (Showing off, nothing new there then :-)) As Buzzards are carrion eaters I doubt if it was chasing it very far. John |
#29
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"Silent Flyer" ] wrote in message ...
I'm also convinced that birds soar for pleasure as well as because they might have to Earlier this year sitting in my garden on a hot windless day, I watched a Buzzard pick up a thermal over a small local wood and climb until it was a speck in the sky. It then closed its wings and dived at great speed until it was about fifty feet above the ground, pulled out and then proceeded to climb again. It repeated the climb, dive, climb manoeuvre three times before I went indoors. Surely that could not have been for anything other than pleasure ? DB Definitely not. I have watched similar behaviour many times. One particular time I was climbing under an nice fat cu where three buzzards were climbing in to the cloud out of sight and then diving out of it about five seconds later, over and over again. Marcel ------------- Why walk when you can soar? |
#30
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impossible for them. (Anyone know the maximum all up
weight of a swallow) Would that be an African or European swallow? |
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