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Peregrine Falcon Aerial fight (1 Viewer)

jnicholes

Well-known member
Hello,

So, I was driving to pick up my mother from work. when I got to her work, I have a habit of bringing my binoculars and looking at Birds. Today, I saw something very interesting and extremely cool. I never thought I would see this happen.

I looked up, and I see a peregrine falcon. I see a second one. They are circling preparing to fight. Eventually, I see this big fight in the air. These Falcons were really mad at each other. Eventually, I saw one of the peregrine falcons do its signature dive swoop. Keep in mind that during this swoop, the peregrine falcon can reach speeds up to 240 miles per hour. He hit the other Falcon during the swoop, and knocked him clean out of the sky, literally.

The winning Falcon flew off, and after 2 minutes, the other Falcon got up and flew off.

That was so cool to see.

Pictures will be coming shortly. I got to upload them to my computer, then I can post them.

Jared
 
"240 miles per hour" when dropped out of an unnaturally high altitude balloon perhaps .... |:p|

They are highly territorial, and I have seen them dive, and drive off even previous seasons singletons, and wandering males etc, as well as all manner of other larger raptors ..... have never seen them knock another one out of the sky though ....

Impressive birds ! :t:





Chosun :gh:
 
Hi Jared,

Eventually, I saw one of the peregrine falcons do its signature dive swoop. Keep in mind that during this swoop, the peregrine falcon can reach speeds up to 240 miles per hour. He hit the other Falcon during the swoop, and knocked him clean out of the sky, literally.

Great observation! I've often wondered how far the various species will really go in a fight for dominance ... it seems Peregrines don't held anything back!

From what I've read, the estimate of a Peregrine's dive speed has been revised downward quite a bit by more recent research. No doubt they are extremely fast though, whatever the actual numbers!

Regards,

Henning
 
.... Great observation! I've often wondered how far the various species will really go in a fight for dominance ...
.
Henning - I've seen two Nankeen Kestrels (not sure if it was two males fighting, or a breeding couple in a mating ritual) lock talons hundreds of feet up in the air, and spiral downward ......

Down, down, down they went - at a great rate of knots - I was wondering how close to the ground they would get before letting go ..... they didn't ! They hit the ground with talons still locked together ! :eek!: I was pretty certain they'd both had it ! such was the speed they hit the ground at.

Thankfully they fell upon about a metre high native grass sward .... after a heart stopping delay - they both flew away - seemingly unharmed ....



Chosun :gh:
 
Hi Chosun,

.
Down, down, down they went - at a great rate of knots - I was wondering how close to the ground they would get before letting go ..... they didn't ! They hit the ground with talons still locked together ! :eek!: I was pretty certain they'd both had it ! such was the speed they hit the ground at.

That's determination! I've often read that birds don't take risks to the extreme as it would pay off evolutionarily, but on the other hand ... that doesn't mean that sometimes individuals take it too far and get killed while doing so.

Glad to hear your falcons were OK ... maybe they could judge the impact well enough to know the grass would safely break their fall?

One fight where I wondered how lethal the participants' intentions really were happened when a juvenile White-tailed Eagle strayed into the territory of a pair of Common Buzzards. The buzzards really suprised me by aggressively attacking the much larger eagle, diving at it with the talons fully extended, and the eagle really was having to throw itself about to get out the way. They kept that up for a good while, sort of taking turns in diving at the eagle, who lost a lot of altitude due to his manoeuvres. At one point, it really flew a full 360 roll while evading. The buzzards left the eagle alone when it was down to tree-top height, and on the other side of the small lake ... probably out of their territory, I guess.

No idea if they had actually sunk their tailons into the eagle's flesh if they had caught him, or wether this as just a threatening gesture. I'd say the eagle did everything to avoid finding out the hard way, though ...

Regards,

Henning
 
those are awesome bird fight stories!

I just did some research on peregrine falcons. According to Wikipedia, peregrine falcons can reach in their hunting dive a top speed over 320 kilometers per hour, or 200 miles per hour.

I wasn't far off.

Since we're talking about stories of witnessing bird fights, let me tell you something that happened a long time ago that I saw. Once, a long time ago, when I lived in Coeur d'Alene Idaho, I was fishing at a place called fernan Lake. Everybody on the dock was looking up and pointing. I look up, and I see a hawk and of bald eagle having it out.

That was cool to see also.

Jared
 
Hi Jared,

I just did some research on peregrine falcons. According to Wikipedia, peregrine falcons can reach in their hunting dive a top speed over 320 kilometers per hour, or 200 miles per hour.

Hm, I'm not sure I'd trust Wikipedia to be the most reliable source on this.

I just found this:

https://www.researchgate.net/public...peregrinus_and_the_Goshawk_Accipiter_gentilis

Actual measured speed of the peregrines was 140 km/h, and further down the page a newer study is a measured speed of 184 km/h (Peter and Kestenholz 1998) is mentioned.

Alerstam points out that "the observed speeds are well below the maximum possible terminal speeds" and points to manoeubrabiliy as a possible reason, but I think it's also worth noting that Konrad Lorenz in his classic "Vogelflug" noted that the top speed of birds was determined by aerodynamic flutter considerations.

Regards,

Henning
 
Hi Chosun,

That's determination! I've often read that birds don't take risks to the extreme as it would pay off evolutionarily, but on the other hand ... that doesn't mean that sometimes individuals take it too far and get killed while doing so.

Glad to hear your falcons were OK ... maybe they could judge the impact well enough to know the grass would safely break their fall?

One fight where I wondered how lethal the participants' intentions really were happened when a juvenile White-tailed Eagle strayed into the territory of a pair of Common Buzzards. The buzzards really suprised me by aggressively attacking the much larger eagle, diving at it with the talons fully extended, and the eagle really was having to throw itself about to get out the way. They kept that up for a good while, sort of taking turns in diving at the eagle, who lost a lot of altitude due to his manoeuvres. At one point, it really flew a full 360 roll while evading. The buzzards left the eagle alone when it was down to tree-top height, and on the other side of the small lake ... probably out of their territory, I guess.

No idea if they had actually sunk their tailons into the eagle's flesh if they had caught him, or wether this as just a threatening gesture. I'd say the eagle did everything to avoid finding out the hard way, though ...

Regards,

Henning
Hi Henning,

I don't know if it was a bl**dy-minded game of chicken, or an accident - nature is not always precise ! I also don't know for sure whether it was combat or a mating ritual. It was pretty much over the paddock where a pair of Kestrels permanently nested in a hollow of a big old dead tree. Yes ! Glad they were OK.

At that property I also had Little Eagles permanently nesting in an emergent tree along the creek line. Black-shouldered Kites would nest back on the Homestead side of the creek within the Little Eagles display and hunting territory, and once there was even a pair of Spotted Harriers that nested in a tree in the creek line a mere 200m from the Little Eagles - wasn't that a tense few months. As well we would have Whistling, and Black Kites cruising by, Little Falcons regularly, Peregrine Falcons at other times (a big female), Wedge-tailed Eagles soaring and gliding overhead - one even buzzed the canopy once. Brown Falcons would be fairly regular too, Black Falcons every now and then, and once a rare Grey Falcon also zipped by at altitude, as well there were often Brown Goshawks lurking, and occasionally Collared Sparrowhawks too. So a big range of species and sizes.

I witnessed many encounters. I can say that all of the Falcons never crossed paths. The Hawks seemed to stealthily avoid conflict too. The Whistling, and Black Kites passed through promptly so didn't cause conflict either. The Whistlers were often in a pair.

That left the Nankeen Kestrels who would harass the twice as powerful Black-shouldered Kites. The Black-shouldered Kites who would harass the twice the size Little Eagles, and the Little Eagles would harass the twice as big Wedge-tailed Eagles.

In all of those encounters it seemed to be the smaller bird that would be the more aggressive, with the larger bird gliding /soaring away. It all looked fairly serious with legs fully extended, talons out, and lots of aerodynamic flips and barrel rolls etc.

The Harriers also kept to themselves except for that rather foolish nesting incident. The Harriers buzzed the Little Eagles as much as vice versa, though they were only there for one season - long enough to raise a beautiful daughter. All 3 then left for a calmer neighbourhood ! It was interesting that the more powerful resident female Little Eagle wasn't totally dominant over the female Spotted Harrier who would give a spirited long legs out defence. Perhaps this was because the female LE was worried about the male LE who was marginally outgunned by the slightly larger male Spotted Harrier. In the end after they finished breeding the Harriers never came back again to nest, but often cruised through solitary hunting which the LE's ignored as long as it was at least 500m from their nest.

You would think the larger birds would dominate but that doesn't seem the case. Of course things may be different if they really get fair dinkum - mostly it's just bluff ... that risk of injury has to be a very big consideration in any situation, and it's always the nesting territory birds that prevail - despite their mostly smaller size.



Chosun :gh:
 
Hi Chosun,

You would think the larger birds would dominate but that doesn't seem the case.

Quite a range of wonderful birds you've been observing! :)

There is a very important physiological law behind the ability of smaller birds to out-fly larger ones: Basically, the power that an organism of mass m can generate is proportional to m^b, with b = ~0.75 for most organisms.

That means that a bird that's twice as heavy as another otherwise similarly-built bird (like the various raptors we're comparing) only has 1.7 times the power, or 85% the power-to-weight ratio.

In flight, the power-to-weight ratio determines how quickly a bird can climb to greater heights, and of course the bird that's on top can dive at the one that's below, and harrass it with impunity :)

Not to say flying skill doesn't come into this ... I've often seen crows harrass buzzards until the buzzard makes one good move and the crow loses the advantage. Usually, it leaves the buzzard alone after that! :)

Regards,

Henning
 
@Hauksen, thanks for pointing that out, and thanks for the link. I had no idea that that was the case. I guess I have to be more careful with where I get my information.

Again, thanks so much for pointing that out.

Jared
 
Hi Jared,

@Hauksen, thanks for pointing that out, and thanks for the link. I had no idea that that was the case. I guess I have to be more careful with where I get my information.

Again, thanks so much for pointing that out.

Thanks to you for sharing your experience, and inspiring such an interesting discussion!

Wikipedia is in fact wonderful and terrible at the same time - nothing wrong with using it as a starting point, and in its defense, it was actually an older version of the German article on peregrines where I first read about radar-based dive speed measurements.

Ironically, this really good bit was removed from the article recently and replaced with the "old" 300 km/h speed claim, quoting an article in some rural German rag as a source ...

Now that I think about it, Birdforum has its own encyclopedia "Opus", which I probably should pay more attention to:

https://www.birdforum.net/opus/Peregrine#Flight

The article there quotes a more careful "reported" 200 km/h dive speed, but at the moment has no footnotes referring to a source on that data point.

Regards,

Henning
 
Hi Chosun,

Quite a range of wonderful birds you've been observing! :)

There is a very important physiological law behind the ability of smaller birds to out-fly larger ones: Basically, the power that an organism of mass m can generate is proportional to m^b, with b = ~0.75 for most organisms.

That means that a bird that's twice as heavy as another otherwise similarly-built bird (like the various raptors we're comparing) only has 1.7 times the power, or 85% the power-to-weight ratio.

In flight, the power-to-weight ratio determines how quickly a bird can climb to greater heights, and of course the bird that's on top can dive at the one that's below, and harrass it with impunity :)

Not to say flying skill doesn't come into this ... I've often seen crows harrass buzzards until the buzzard makes one good move and the crow loses the advantage. Usually, it leaves the buzzard alone after that! :)

Regards,

Henning
Hi Henning,

I haven't come across this before. What is this equation? and where does it come from? Could you explain a bit more?

Crunching the numbers, nothing touches a Nankeen Kestrel for "power" .... not a Wedge-tailed Eagle, nor even two of probably the most powerful raptors - the Crowned Eagle, and the Harpy Eagle !
The Peregrine Falcon is also put in the shade ...... ?

I can't imagine anything other than aerodynamics and ballistics applying.

ie. Aerodynamic Cd, Frontal Area, and Sectional Density. When soaring Wing Loading becomes more dominant.

Most Wedge-tailed Eagles that I see really don't bat an eyelid at being harassed by Magpies and Ravens. No matter how hard they flap and how much energy they expend they can't keep up when the Wedgie spreads it's wings with fingered wingtips and just circles skywards out of sight ! :eek!:

I would think that the Peregrine probably has the among the highest Sectional Density of any raptor.

I have seen a Wedge-tailed Eagle female of ~2.5m wingspan soaring on thermals with a rabbit that she had caught, and what I can only take was "playing" with it ! She would drop it, watch it fall, and then dive in a folded wing stoop to catch it and soar back up again. This process happened a few times, and she would catch up to the falling rabbit in what looked to be about ~500 - 1000m or so. Granted the lifeless rabbit didn't present the most aerodynamic profile, but she easily out accelerated the free falling rabbit. I was really quite surprised by the speed of the Wedgie in a stoop.




Chosun :gh:
 
Hi Chosun,

I haven't come across this before. What is this equation? and where does it come from? Could you explain a bit more?

Of course! I'm always happy to find someone who agrees that math can actually be highly interesting! :)

I found the equation in "Zoologie" by Wehner/Gehring, 22nd edition, Stuttgart/New York 1990.

It's called "metabolism equation" (my translation from the German original), and stated as

E dot = a * M ^ b resp. log E dot = b * log M + log a

(M body mass, a mass coefficient, b mass exponent)

"For a wide spectrum of organisms, b is 0.75. b < 1 universally means that the increase of the energy turnover falls behind that of the body size, the energy turnover per unit of mass (specific metabolism rate [E dot * M ^-1]) accordingly decreases with increasing body size."

As E dot (first derivative of energy for time) is power, the specific metabolism rate comes down to a power-to-weight ratio, assuming life under standard gravity :)

From the graph in the book, the more accurate value for b as applicable to birds actually is 0.8, as homeotherm organisms have a slightly higher metabolism rate than the aforementioned "wide spectrum of organisms", which includes unicellular organisms.

The metabolism rate defines the maximum continuous gross power an organism can develop - in an approximation, as different specialization can lead to different proportions of metabolistically active body mass.

(For example, a Gannet due to its different specialisation will probably have a lower value of b than a bird-of-prey.)

For birds engaging in aerial fights, that basically means that smaller birds generally have relatively more powerful "engines" than larger birds.

That means that as the fight continues, as a general rule smaller birds will tend to outperform larger birds by virtue of their superior power-to-weight ratio, which is most advantageously used to gain height.

Aerodynamics haven't even entered the picture yet ... it would be the same for monkeys climbing a tree, with a mammalian predator coming after them.

ie. Aerodynamic Cd, Frontal Area, and Sectional Density. When soaring Wing Loading becomes more dominant.

In an aviation context, the pure power-to-weight ratio is developed into complex "specific excess power" maps which take these factors into account. (Soaring actually is of interest mainly to glider pilots, who always operate at negative specific excess power :)

However, these complex maps are mainly necessary because jet engines are not constant-power propulsors. For propellor propulsion, where power is approximately constant over much of the speed range, the pure power-to-weight ratio is a very good indicator of tactical capabilities, and I'd say when we're talking about birds, it's probably the same for a "muscle power" powerplant.

For a small bird dived at by a large bird, the key really is not to get hit while evading the attack for as long as it takes the smaller bird to bring its energy level - measured in kinetic plus potential (=height-dependent) energy - up to that of the larger bird.

Regards,

Henning
 
@Hauksen, I love mathematics myself. That was quite interesting to read. I actually saw proof of what you just said today while driving. I was driving home when I saw these small black birds chasing away a really large Hawk. It was quite interesting to see. The hawk was running away.

I couldn't tell what kind of bird and what kind of Hawk it was, though. Still, it was interesting.

Jared
 
.... I found the equation in "Zoologie" by Wehner/Gehring, 22nd edition, Stuttgart/New York 1990.

It's called "metabolism equation" (my translation from the German original), and stated as .....
Hi Henning - thanks for the explanation. The metabolism 'power' makes more sense .... as part of the overall performance parameters :brains:

Closely following on from metabolic power would be heat transfer - ie. the ability to dissipate the heat generated without cooking muscles or other vital organs. Some of this would also be related to genetic make up - ie. muscle mass and distribution. From what I have read previously I think feral pigeons (and some sort of migratory goose or something from memory) have the highest percentage of chest muscles (more so than even peregrines) allowing them to achieve the fastest speeds in powered level flight.

It would be interesting to read aerodynamic studies of birds.

I have an idea that aerodynamic considerations could play such a large part that they may even trump and reverse metabolic considerations. The aspect ratio of the wings plays a large part, as does total lift: weight, and drag. In a stoop, 'sectional density' must also play a key part. Outright size also plays a part in other situations.

A lot of it comes down to aerodynamic efficiency (and fitness for purpose), and conservation of energy.

When trying to photograph (unsuccessfully I might add :) Swallows and Swifts in flight I couldn't imagine any bird being able to fly them down. However one day I had a close encounter (a few feet above my head !) of a Welcome Swallow being mown down by an Australian Hobby - the larger bird seeming to have the aerodynamic advantage.

Similarly, the reason many large Eagles, Kites, Harrier, and Hawks seem to be able to casually out glide /soar their smaller (and usually black or black and white!) snarky protagonists is because of that better lift: drag parameter, confidence in that, and just plain old conservation of energy. I have seen many a Magpie or Raven have very long and embarrassingly lonely glides back down to the canopy after trying to tackle Eagles etc that just soar up out of sight without expending even a fraction of the energy.

I think it is very interesting that we are now seeing the common 'winglet' design on commercial aircraft which mimics the slotted and furled wingtips of Eagles etc. Raptors are just so impressive ! :D




Chosun :gh:
 
Hi Chosun,

Closely following on from metabolic power would be heat transfer - ie. the ability to dissipate the heat generated without cooking muscles or other vital organs.

That's in fact an important consideration for prolonged travel. Migratory birds choose their cruise altitudes to provide a sufficiently large temperature drop to keep them cool despite constant exertion. If that's not possible, they have to compensate by water evaporation, which can become a limiting factor to travel distance as the bird gets dehydrated.

I believe it was Nachtigall who performed wind tunnel tests with pigeons breathing air through measuring tubes to allow perfect monitoring of their metabolism. (I don't have the source at hand, but at least Berthold's "Vogelzug" mentions Nachtigall's trials in a general form.)

I have an idea that aerodynamic considerations could play such a large part that they may even trump and reverse metabolic considerations. The aspect ratio of the wings plays a large part, as does total lift: weight, and drag. In a stoop, 'sectional density' must also play a key part. Outright size also plays a part in other situations.

A lot of it comes down to aerodynamic efficiency (and fitness for purpose), and conservation of energy.

All these factors play a role in aviation as well, and within the range of sensible parameter variation, specific excess power has proven to be the dominating factor in one-versus-one air combat. Aerodynamic design determines what manoeuvres are possible in the confines of the available energy, but it takes second place to specific excess power.

I have seen many a Magpie or Raven have very long and embarrassingly lonely glides back down to the canopy after trying to tackle Eagles etc that just soar up out of sight without expending even a fraction of the energy.

Well, that would seem to be a mix of powered and unpowered (but soaring) flight. Soering in thermals, it's generally a low absolute sink rate that's advantageous, so birds with a low wing loading should have an advantage there.

I guess you probably have more powerful thermals in Australia than we have in Germany :) It also seems that the Common Raven we have here in the North is larger and heavier overall than the Australian raven species.

It my impression, based on my limited personal observations, that Common Raven usually lose a duel against the smaller Carrion Crow, and on one occasion I saw a raven harrass a Western Osprey, with both birds being about equal in their ability to gain altitude.

Regards,

Henning (HoHun)
 
.


When trying to photograph (unsuccessfully I might add :) Swallows and Swifts in flight I couldn't imagine any bird being able to fly them down. However one day I had a close encounter (a few feet above my head !) of a Welcome Swallow being mown down by an Australian Hobby - the larger bird seeming to have the aerodynamic advantage.


Chosun :gh:

The main prey of the European hobby is hirundines. Often the first indication that there is one about is when the house martins start alarm calling. In this case, as you rightly say, is not so much about outright speed but maneuverability.

You analogy to aircraft wings is apt here. The battle of Britain was won by the superior maneuverability of the spitfire despite the fact that the Me109 was possibly slightly faster in level flight.

Buzzards and eagles have large broad wings for soaring and carrying off larger items of prey, whereas falcons are built for speed and maneuverability. The former can stay airborne almost effortlessly for long periods whereas the latter are more your smash and grab merchants (bombers against fighters to use the aircraft analogy again?)
 
Hi Paul,

You analogy to aircraft wings is apt here. The battle of Britain was won by the superior maneuverability of the spitfire despite the fact that the Me109 was possibly slightly faster in level flight.

Well, I didn't mean to argue that specific excess energy is the only decisive factor in any aerial fight. (Otherwise, you'd be talking about the Battle being won by the famous Hurricane, which was every bit as manoeuvrable as the Spitfire, and available in twice the numbers :)

My point really is that if there is no decisive result in the opening seconds of the fight, and both participants are down to the same energy level, then specific excess power comes into play.

So when you see two birds in a fight like that, you can usually predict what's going to happen next: The smaller bird will climb above the bigger one and either fly away if it's not interested in continuing the fight, or begin to harrass the bigger bird if it is.

Regards,

Henning
 
Hi again,

Last week, I happened to witness a bit of an aerial fight between White-tailed Eagles.

I was quite far away, so picture quality isn't good, and I admit that I only identified the birds as eagles on the photographs. My attention at the time was actually focused on a flock of a dozen cranes that took flight when the raptors appeared. (Which I took for "Common Buzzards, most likely".)

On the next day, I saw one adult White-tailed Eagle and an immature one in the area, as well as an artificial nest, so maybe the territorial adults are trying to get the immature eagle to leave their territory.

Regards,

Henning
 

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