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Discussion of other Raptor species; their anatomy, biology, ecology, etc.
Topic Started: Sep 16 2007, 11:04 AM (18,109 Views)
ostrich2
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Raptorman,Dec 28 2007
05:27 PM
Keep in mind it is the prey that greatly controls the predator's/raptor's shape and behavior. To be successful the raptor must adapt to be successful as a predator of specific prey. In your mentioned sighting the RT does stand a chance of success from a flock of pigeons. To some extent the flock offers protection for most of the members BUT often at the peril of one member. However, even in a flock situation certain criteria must be met and mistakes need to be made on the part of the prey probably as much as certain skills need to be present within the raptor. In reality a RT vary rarely would have success with a single pigeon. The pigeon is simply too maneuverable compared to the broad winged, fan tailed buteo (far better designed for soaring). Bill :D

Yes, although the apparent interaction was interesting there may not have been any specific intent on the part of the RT - if you imagine two circles side by side that just touch at one point, that was kind of the pattern, as the RT soared around in one circle, the pigeons were circling around on the other and when they got near the pigeons would react and pull further away. But the RT never changed its flight in response. The pigeons reaction I would tend to expect even without any immediate threat - as you said, the prey will have instincts to minimize any chance of blundering into danger stupidly.

So one possibility is the RT wasn't intent on the pigeons at all, another could be it was soaring hoping for a rare opportunity to catch a careless member of the flock. I wonder if it could also have been testing the pigeons to see if there are any wounded or sick members that could make for an easy catch? There are a number of predators that adopt this type of "testing" strategy - they will force the prey into an avoidance not expecting to actually succeed, but simply to force any weak members to reveal themselves. If the prey demonstrate they are healthy and able to avoid the predator the predator knows not to expend unnecessary energy on a chase it cannot succeed in. This is common I believe with pack hunters like cats and wolves. I'm not sure if a raptor like a RT would ever use this type of strategy?

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Raptorman
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ostrich2
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Raptorman,Dec 29 2007
01:51 PM
I can't say I have witnessed the circling pattern you mentioned. That is interesting. Were they flying at approximately the same level? The RT normally needs to be within the flight plane of the pigeons OR above. One of the flight weaknesses of most raptors (accipiters excluded) is the ability to climb quickly. To evade a raptor the prey needs to go up OR get to ground cover far ahead of the raptor. Accipiters excel at climbing and entering some forms of vegetative cover in pursuit of prey (especially birds). Bill :D

They were flying up maybe 30 or 40 feet above the top of this apartment building, but trying to recall I think the RT was probably lower than the pigeons for the most part, so it may be the actual proximity was less than it might appear looking from below. On the other hand, it's hard to imagine what else in that area the RT might have been looking for. When the RT finally drifted over to the other side of the street, it did go over a park area with quite a bit of grass areas (although currently snow covered) with baseball and soccer fields, so that might well be a good hunting area.
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ostrich2
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Out of curiousity, I inquired on the photo page for the Cape Cod hawk about what the prey was, and the person stated it was indeed a blue jay. That could mean the size is even a bit smaller than previously suggested, so perhaps a slightly better argument for sharp-shinned.

Although I gather for this one it's impossible to really tell for sure between Coopers and sharp-shinned, I still found this one quite valuable to try with, as it gives you a better feel for what the actual sizes are based on something concrete.
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ostrich2
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Raptorman,Dec 28 2007
08:55 PM
Here is a new id species. Good Luck.

Bill :D

Bill,

I'm just getting to this one, and I don't have a good idea what this is yet, but I have some ideas. The first thing I haven't determined yet is what type of bird this is.

Looking at the bird at first, my first rough impression was this is reminiscent of some type of owl. The head has got a rather circular shape to it, which is perhaps the most owl-like characteristic, although it doesn't really have a very prominent facial disk like most owls.

I do notice although not really strikingly white like a snowy owl, this bird does have whitish and greyish plumage all over its body, as well as what seems to be somewhat thicker and finer plumage around the face. That makes me speculate that this might be a species which may be adapted for snowy climates, like the snowy owl.

I also notice this bird does not have any visible ear tufts, so owl or not this eliminates some possibilities.

One other thing that made me think this isn't really an owl is that the bird seems to have a visible bulge in the crop area, suggesting it has something in a crop, and Bill has mentioned previously that owls are distinctive in not having crops.

The other type of raptor which I know of that looks somewhat owl-like is the harrier. So at this point I'd speculate this is some type of harrier, although I don't know yet which species it might be. The plumage doesn't resemble a northern harrier to me. That's my best guess so far anyway, others are free to disagree :D
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ostrich2
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Actually I think I may have spoken too soon dismissing the Northern Harrier - I found a field reference which states that the Northern Harrier like the American kestrel has distinctive male-female plumage. The bird does seem to fit in fairly well with a male Northern Harrier.
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Raptorman
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Patti
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Happy New Year...been caught up with family affairs here.

Regarding Bill's I.D. photo---Ian, I too was leaning toward some kind of Harrier, but Bill's bird's face didn't match any photos I was looking at...or drawings, so I've remained stuck in the Harriers, but don't know how to keep looking. I cant' find anything with that white eye patch below the eye.

Bill: To answer your question about my blackened Sony digital camera screen, it does seem I'm always facing west when this occurs, now that I think of it, but I'm wondering if the sun may be south, or behind, me? It is still somewhat early in the day when this happens--but not mornings.

I tried to video a RT dive-bombing what may have been a Cooper's or Sharp-shinned and it was futile...even if the screen was not blackened on that particular event. I had to make a choice and went with watching the spectacular sight, rather than try to track the birds. My videos are horrendous. Another hawk was in our pine tree and I was running to catch it from both sides...more like Animal Planet's Funniest videos than anything serious. I am VERY enthusiatic, though. :P
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Patti
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Bill! :lol: Good thing you cautioned me...and that appears to me like a small white eye patch against grey. I'll be back...must go to mother's.

The glare is on the (LCD) screen.
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Patti,Jan 1 2008
06:45 PM
Bill!  :lol: Good thing you cautioned me...and that appears to me like a small white eye patch against grey.  I'll be back...must go to mother's. 

It's interesting what different people notice - I hadn't actually even noticed the white eye patch - I had noticed the different shades of grey/white around the head that kind of made it look hooded. Then in the Peterson field guide I found this for the Northern Harrier:

Adult male: Head is medium gray...Gray of head extends onto upper breast so that head appears hooded
...Rest of underparts are white, with rufous spotting on breast, sometimes heavy and extending onto belly.


If I'd noticed that white strip I might too have wondered about matching that up, as it does look like something you might imagine is a distinctive for that species. That description matched in several respects though so I figured it was a good condidate.

I'm also curious Bill if the inference that the bird is not an owl because of an apparent crop is always valid. I interpreted the bulge in the chest area to be that the bird had recently eaten and had something in its crop, but it occurred to me I'm not sure what happens when an owl swallows a large rodent for example.

I will say this though about the Harrier - the field guide illustrations/pictures don't seem to really give you a good idea of the owl-like face - if I hadn't seen this shown so clearly (and mentioned as well) in the "Birds of Prey Are Cool" video I might not have made that association.
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Raptorman
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ostrich2
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The song doesn't say much other than there's a resemblance with the owl - the field guide doesn't even mention the similarity though. That was enough though to trigger me to look at the harrier as a possibility.

I'm the great fooler, the grey ghost
I have many names, but there's one you'll hear the most
My newest name has direction in it now
If you see my face, you might think I'm an owl (Northern harrier)


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