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Discussion of other Raptor species; their anatomy, biology, ecology, etc.
Topic Started: Sep 16 2007, 11:04 AM (18,137 Views)
Raptorman
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ostrich2
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Raptorman,Oct 8 2007
01:59 AM

If the prey is flying quickly AND the falcon has great altitude (500' to 1000') above the prey binding to the prey is very difficult. So a passing strike with the talons is the best means of assuring a kill. The talons (rear only) will act like two sharp knives slicing into the body or wing of the prey. This can often result in the prey's death. The speed of the stoop will cause the falcon's momentum to make it impossible for the falcon to "stop" before hitting the ground so, the falcon changes direction to fly up until gravity slows the falcon enough for it to again change direction at a much reduced speed and fly to the ground to retrieve it's prey.

The "fist" technique refers to the fact the front 3 toes are tucked into a fist BUT the rear talon is in a normal position. There is no force that can keep the front 3 talons in a position during a strike and the talon shape is not designed for striking on a pass by. The toes will simply fold and the talons are curved the wrong way for affecting a slicing action. Only the rear talon is designed for a slicing action, is in the right position and offers the affective shape to slice/kill during a stoop.

Your analogy doesn't allow for the fact the surface the falcon strikes is also moving in the same direction, it is not stationary. Also the talons have a much better shape for cutting through flesh. Cleats are actually shaped to provide Resistance (traction).


Firstly, yes of course you are correct there may be a number of situations in which the peregrine may not need to execute a high speed stoop from above to catch a prey bird, so my thought about the possible danger to the peregrine would only apply when they are hitting the prey at full speed.

I found another clip from the Raptor Force documentary which is even better - this one has the actual footage of the stoop from the back mounted camera:

Raptor Force - Stoop

One thing that isn't clear is whether the peregrine typically is already pulling out and is moving parallel to the ground or close to it when it strikes the prey, or whether it hits while still in a full drop and then pulls out after the strike. That would certainly make a big difference to the type of impact the peregrine experiences.

In my opinion the movement of the prey shouldn't be a significant factor either way, as even if the bird was moving 50mph (a very fast speed which it almost certainly wouldn't typically), all that would mean is the relative speed of impact would be 200mph instead of 250mph, still leaving an enormous speed at contact. You are of course correct that a shoe cleat isn't the same thing as a talon, and I chose a cleat as an extreme example of the kind of scenario I was thinking of.

I think based on what you're saying that probably the danger to the peregrine is indeed a lot less than I originally thought, I still wonder if it's zero. Although probably the vast majority of times the rear talons would just cut through flesh or feathers, I still wonder what might happen if there was an impact with either hard bone or tougher connective tissue. In the car scenario, if I had a hook shaped like a rear talon pointed in the direction of motion as the peregrine does, if it doesn't cut through the ground cleanly and gets stopped or caught on something, you'd think it would still do damage. Perhaps the peregrine can control where it impacts the prey, but considering the speeds involved you'd thinking just hitting the prey successfully at all is a difficult enough achievement.

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Raptorman
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Bea
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Raptorman,Oct 6 2007
03:41 PM

......
(Bea: This note is a reminder for you. I use the same system when deciding on the species of raptor, when deciding on likely prey. Shape, size, color, location, time of year.) (Squab are usually available year round as Pigeons are not photoperiod or seasonal breeders.) Bill  :D

:chk: Thank You Bill! :D

My husband and I had the pleasure today of watching an osprey hunt for fish (or should that be fish for fish? :lol: ). It was awesome. Will have to see about some pics. Hands were shaking too much from excitement :lol:
Patti, I subscribe to WildBird magazine, and I do like it a lot. They've had some really nice articles about Raptors, but, they don't have something on them every time. However, still well worth my $$. Have learned so much about Hummingbirds and other feathered friends.

The Brisbane Cam, is that the one where two little ones died recently? Paula has been updating us over in Chat about that nest. Will have to take a look --- I wish there were more hours in the day!!! :tic:
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Raptorman
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Bea
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Hi Bill, I went to the link, but it does not play/open in a player?

Good info though, and it makes sense that they would have different vocalizations as they become accustomed to certain situations.

I believe Dr. Sharpe is trying to train Hyde (the Golden) to be able to take him to lectures and schools etc... Would a certain "tameness" not be required in order to bring this bird close to kids (for example?)
I know that Pimu (the Bald) did not work out well for that sort of thing, and Hyde seems to take to humans better.

How close did you bring your birds to people, and, did you ever have any "bad" situations happen while on one of your events? How did you prevent any dangerous situations?

Thanks Bill :)

Oh, I almost forgot THANKS SO MUCH for the pictures above of the Osprey nests.
WOW, :o that is some high tower !!! :o
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Raptorman
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Bea
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Bill, call me blonde :bld: :lol: I forgot that I didn't have Real Player on my work computer :lol: . Installed Real Player and was able to hear the Golden call. Now, that sounds more eaglish, doesn't it? :D

I have seen both videos you posted, and loved them. I think it speaks very highly of your professionalism and your loving care for your birds that in all the years you have been teaching, you have had no injuries or mishaps. And to have them travel sometimes thousands of miles and then "perform" (so to speak) is just unbelievable.

Yes, I have heard Dr. Sharpe mention that he needs permits to be able to use the birds as teaching subjects. (Or even just to have Hyde and Pimu)

I'm looking forward to the pics of the children, but, please take your time with posting pics, do not rush yourself!! I'm still trying to find a good pic of my Osprey encounter. As I had feared, most are not clear enough. The bird was far away, and I really was excited to witness the "hunt" for the first time :lol: . But I am certain it was an Osprey.

Regarding the quizz, I must admit I have not had a chance to study much lately :blsh: .
I usually only have the weekends and late nights, and have been under the weather this past week. I will get to it, and will not be afraid to be wrong, just gonna take a little time! (I've been out of school soooo long, it's hard to get back to studying :lol: ) but Oh So Much Fun!!!
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Raptorman
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ostrich2
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Raptorman,Oct 8 2007
04:20 PM
Injuries likely do occur. Even deaths of these raptors BUT it is helpful to remember they have evolved and adapted over millenniums to be superior in their skills over their prey. They have even adapted to the urban habitat were the risks are even greater for life threatening/ending encounters with glass, steel, concrete, vehicle, wires, chemicals and humans. I have always been in awe that more do not misjudge their altitude and crash into the ground during a stoop.

Yes I certainly agree.

Getting back to the original question, oart of the reason I brought up my scenario was because the reference I originally quoted implied there was not unanimous agreement on the actual method of strike used by the peregrine. I interpreted it to mean there were two basic hypotheses:

1. The peregrine strikes in the stoop keeping all of its talons balled up so that it does not slash at all but simply hits the prey (and presumably stuns it - call this strike only)

2. The peregrine strikes in the stoop with slashing of the talons (and from our discussion this realistically would probably be the bird slashing through the prey with the rear talon with the others still curled up - call this strike and slash).

It's indeed exactly because of the adaptation of these raptors to the risks and requirements of successfully catching their prey that makes understanding the potential danger to the bird relevant in deciding which of these is more likely. For example, if just for the sake of argument, someone could show the strike only method would be just as effective for successful hunting, but would pose fewer risks than the strike and slash, then you would expect natural selection to have favored strike only and eliminated strike and slash. Of course in real life situations the choice between two strategies for a species can be a very delicate tradeoff between risk and reward - and as you mentioned the behaviour of the prey makes a difference.

So if my scenario speculating that the strike and slash method could be risky to the peregrine had been correct, and there were reason to think the strike only method could result in successful stoops, I would have concluded that the strike only method is almost certainly the correct one.

This is a bit of an aside from the main issue, but I mention it because it is often very unappreciated the enormous effect that even small differences in survival rates can have on a species, and it's certainly just as relevant to the eagles.

Biologists can in some cases actually calculate something which is called a selection coefficient of a trait - which is a fancy way of measuring how much the chances of survival of an individual is increased (or decreased) if it has that trait. A selection coefficient can often be very small - 0.01 means that the animal has a 1% extra chance of survival.

What is very surprising is that an survival advantage of even 1% can result in that trait spreading remarkably quickly. This happens for the exact same reason as compound interest can make amazing amounts of money over time - 7% compound interest doesn't sound like a lot, but it will double your money over only a few years. So if the peregrine's attack method made even a bit of difference to its success, it wouldn't take much for that to have an enormous effect on the species. Natural selection is an amazing powerful force affecting these creatures.
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Patti
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Bill, I'm going to have to begin my studies soon and tackle our quiz. I think I'm finishing up the work that has led me away from this thread for some weeks. I do own Raptor Force and will review it again soon, but it is an amazing PBS production and sent chills up the spine the first time I viewed it. It can be purchased over the PBS website, which is probably:

PBS -- Look for Nature series here

I will take this chance and post the above link. Bea, you will love this video! I'm fairly certain, but not positive, of course, that I saw an osprey close to the intersection of the 101 FWY and Las Posas Rd about 3-4 weekends ago. The bird has such a pronounced wing hinge hump from the underside from high above that the only thing I could think of was an osprey. It was large, but clearly not a turkey vulture. Usually all I see are Red-tails while we're out driving, but this was not a Red-tail or turkey vulture and it WAS exciting!

Ok, here's the bad news...I've checked into the link I've posted for you and cannot find Raptor Force anywhere in the Nature series...and my own personal copy definitely is part of the Nature series. ??? I do recall that I had to wait some months before it was able to be shipped. There were several delays and I had to confirm that I still wanted to purchase it. Maybe it is reissued with each PBS replay?

Sorry for rambling here and think I'd better call it a night. Hope to come back here tomorrow and carefully read through the pages again. I've been away longer than I wanted...and am looking forward to my BirdWorld magazine, Bea.

Thank you for the wonderful photos, Bill. I envy those lucky children! Great photos of the osprey nests. I hope you continue to share more photos as time permits.
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Naturegal
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Thank you Bill for your great photos, videos and information. I have learned so much from your posts and truly appreciate the time you have taken to educate us.
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