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Peregrine falcon maximum speed (2 Viewers)

D

daveking66

Member
Dear birders,

I know this has been touched on before, but I'm looking for a definitive answer (if such a thing exists) on the maximum swoop speed accurately measured and verified for a Peregrine falcon.

The generally accepted figure which gets bandied around on posts on the net (and by the RSPB for that matter) is 242 mph, which was apparently recorded by Ken Franklin in the (1999?) National Geographic film Terminal Velocity. From various posts I have seen (including this forum) there is debate over the veracity of this claim:
http://www.birdforum.net/archive/index.php/t-10539.html

I haven't actually seen the film myself but apparently the 242mph was recorded after the cameras had finished filming. The top speed filmed was apparently 182mph.

The only other attempt (that I am aware of) to measure speed accurately was conducted by Dr Matthias Kestenholz of the Swiss Ornithological Institute in 1998. I've attached the original scientific publication (in German, but with English abstract) in case anyone is interested. The speed recorded was 115mph.

There was also an article on the Swiss study in the independent which reports that previous estimates of peregrine speeds of 250mph being regarded as wildly exaggerated:
http://www.independent.co.uk/news/peregrines-are-fastest-bird-in-world--official-1194624.html

In light of this the Ken Franklin claim does seem high. Does anyone know if either of these claims has been verified, or what the Guinness book of records has to say on the matter? I haven't been able to find anything else online about the officially accepted maximum recorded speed and the Guinness book of records website doesn't provide this information.

I've also tried contacting the National Geographic asking the same question (they never got back to me)

This is my first post to the forum and if someone can shed any light on this I'd be grateful.

Thanks for your help.
 

Attachments

  • Peter & Kestenholz 1998 Ornithol Beob Sturzflüge - Wanderfalke - Wüstenfalke.PDF
    557.7 KB · Views: 742
I am not a scientist but wonder if tracking radar is sufficiently accurate in the case of a peregrine. A vertical track will not take into account the angle the bird stoops at so I imagine the view point can make one hell of a difference.( I say this before reading the methodology and findings by the learned Doctor).

A long time ago I read a report/discussion by an aeronautical engineer (or similar)suggesting the falcon cannot do more than about 90 mph in a stoop and he cited all the guff about terminal velocity, drag being equal to weight etc etc. All well and good but it does not explain how these birds catch up with sky divers who are known to be doing 120 mph at the moment the bird hits the lure.

In some cases high speeds have been achieved using instrumentation attached to the bird...surely that would increase drag?

I can imagine extraordinary speeds can be achieved with the benefit of downdraft or wind shear. I think engineers should take into account that the bird is not a dead weight so should not be compared to one.

The debate is an interesting one ...perhaps a job for 'Myth Busters'.

I do think that 240mph is laughable...I imagine at that speed a peregrine would not be able to open its wings to pull up!...but who am I?

I do not think the answer is out there....yet.


BTW A warm welcome to BirdForum :t:
 
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From my parachuting days, if you fall in the stable position terminal velocity is about 120mph but if you curl up you can get up to 185 mph. That is how parachutists catch up when trying to make a formation.
 
http://jeb.biologists.org/cgi/content/abstract/201/3/403 calculates a theoretical maximum of an 'ideal falcon' as between 138 and 174 metres per second, (approx 305 to 390 mph). 240 mph appears far from implausible in the light of this. Personally I think some of those who dismiss these claims may never have watched a Peregrine perform a full-on stoop. The speed is utterly breathtaking, and I have very little difficulty believing it's four times faster than a duck.

Graham
 
Thanks for that a.dancy,

From Vance Tuckers calculations (1998) the theoretrical speeds of a peregrine falcon swoop is in excess of 300mph -amazingly fast!

What I'm really looking for though is what speeds have actually been accurately measured and verified.

Information on this proving to be more elusive though!

Dave
 
247 MPH has been recorded by NASA scientists using a falconer's Peregrine, a hot air balloon and speed measuring radar but this doesn't strike me as a very natural situation (not least because the balloon from which the bird was released was at an altitude considerably higher than your average wild Peregrine's patrol ceiling). The experiment was filmed by the National Geographic network and I daresay it's on YouTube somewhere.
 
John B (not the sloop) said:
247 MPH has been recorded by NASA scientists using a falconer's Peregrine, a hot air balloon and speed measuring radar but this doesn't strike me as a very natural situation (not least because the balloon from which the bird was released was at an altitude considerably higher than your average wild Peregrine's patrol ceiling). The experiment was filmed by the National Geographic network and I daresay it's on YouTube somewhere.
Click to expand...

http://www.youtube.com/watch?v=j3mTPEuFcWk
Here is the link, it mentions 242 MPH.
 
In addition to what others have said re terminal velocity - which is usually a theoretical calculation of gravity, drag coefficients, etc., there is also the extra speed birds can add by manoeuvering.

I've watched hunting Peregrines and (more often) Hobbies. I have absolutely no proof - but I'm convinced from observation - that birds can increase speed by turning. This must be related to the way ice skaters increase their rate of spin by pulling in their limbs, against the centrafugal (centrapetal?) force.

I've watched falcons suddenly catch up with (and catch) prey while gliding in a tightening arc. {Perhaps there's a physicist out there who can confirm this phenomenon.}

If a Peregrine stooping at, say, 150mph. makes a tightening turn, how much could its speed increase? Ever been hit on the wrist by an object you've been twirling on a cord, when the cord wraps around to suddenly shorten?
 
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Indeed, ice skaters change their angular velocity (or that of the universe - I can never remember ...) by changing their moment of inertia at roughly constant angular momentum. If a peregrine with constant or increasing vertical momentum accelerated horizontally, i.e. changed direction, its kinetic energy, i.e. its speed, would increase, essentially for the same reason. This is of course an oversimplification, since ... oops, have to go, sorry!
 
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Momo said:
Indeed, ice skaters change their angular velocity (or that of the universe - I can never remember ...) by changing their moment of inertia at roughly constant angular momentum. If a peregrine with constant or increasing vertical momentum accelerated horizontally, i.e. changed direction, its kinetic energy, i.e. its speed, would increase, essentially for the same reason. This is of course an oversimplification, since ... oops, have to go, sorry!
Click to expand...

Momo are you actually IN the Large Hadron Collider?;)

ps, excellent thread, strange it's proving so difficult to verify.....
 
Momo said:
Indeed, ice skaters change their angular velocity (or that of the universe - I can never remember ...) by changing their moment of inertia at roughly constant angular momentum. If a peregrine with constant or increasing vertical momentum accelerated horizontally, i.e. changed direction, its kinetic energy, i.e. its speed, would increase, essentially for the same reason. This is of course an oversimplification, since ... oops, have to go, sorry!
Click to expand...

Momo,

I was right then!! Thanks!

H
 
Birders,

Just to provide an update on this I've now written to the Guinness book of records for confirmation what the highest speed that they recognise that has actually been recorded for a Peregrine falcon swoop. Don't forget it's the actual verified speed that has actually been measured that's of particular interest to me, and not the theoretical speeds which have been calculated.

The latest record I could find in the guiinness book of records was for 124mph stated in their 1998 edition. After that though there is no mention whatever of any speed records, let alone bird speeds. From 2000 onwards it resembles more an offshoot of heat magazine with lots of big glossy pictures of celebrities rather than hard facts about the animal kingdom and the man made realm. Norris McWhirter would be turning in his grave!

I await their response with baited breath
 
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