Silver Swainson's Hawk?????

posted by Jerry Liguori at
on Thursday, August 1, 2013 

Cathy Sheeter sent me these photos with the title "Silver Swainson's", and I was curious what that meant. Cathy has a knack for finding interesting birds (and wrote a blog about it I'll post soon). So, when I scrolled down to see this hawk, I was stunned by its beauty, and intrigued by its lack of pigment. I have not seen a Swainson's Hawk like this before (not sure anyone has), nor a hawk of any type with this odd coloration. Does anyone want to comment on the bird? The white face is beautiful, as is the gray body and leggings. Some might suggest a hybrid, and if so, let me know with what and why, it would be interesting to hear. Sorta has a Mississippi Kite feel but that highly unlikely hybrid can't really be justified. And to be clear, I don't think it is a hybrid, but fun to ponder
Anonymous Jerry Liguori said...

A sidenote....Tony Leukering sent me a slide of a Ferruginous Hawk years ago that had a chest and belly similar to this. I posted it a few months ago in the blog titled "Aberrant Plumaged Raptors"

August 1, 2013 at 9:28 PM  
Anonymous Derek Lyon said...

From the neck on down the bird looks Swainson-like. The head is a whole different story, 2 birds came to me as soon as I saw the first photo. Mississippi Kite or Rough-legged Hawk both have similar heads but no body similarities. The bird does seem to have a Ferruginous Hawk feel about the head but it doesn't have the wide gape of a Ferrug that was evident in Tony Leukering photo in the older blog post. I'm still undecided.

August 2, 2013 at 1:42 AM  
Anonymous Ron Dudley said...

Wow, that's a strange looking (and beautiful) Swainson's. I see what you mean about its resemblance to a kite. You just never know what you're going to find, "out there". Neat bird!

August 2, 2013 at 4:42 AM  
Blogger Mia McPherson said...

What a neat looking Swainson's! Perhaps this is a form of leucism?

August 2, 2013 at 5:00 AM  
Anonymous Jerry Liguori said...

I'm really scrutizing this bird and the more I look at it, the more I wonder...

I won't say much more because one can only speculate. But that white head, gray color, and what looks like it could be a reddish-brown eye are odd. Even the bill looks small. But who knows?

August 2, 2013 at 4:58 PM  
Anonymous Jerry Liguori said...

Even the banding in the primaries and secondaries are a bit smudgy ...but buteo hybrids are rare enough. Hybrids between different families are nearly unheard of. But I love to wonder, and it is a neat bird!

August 2, 2013 at 5:43 PM  
Blogger Steve Bauer said...

The head size and shape, including the gape, seem fine for Swainson's Hawk to me. A Ferruginous Hawk has such a long head and thick neck and I don't get any hint of that from these photos at all.

August 2, 2013 at 7:27 PM  
Blogger Jerry Liguori said...

Oh yeah, totally agree Steve...I haven't waivered from it being an oddly colored Swainson's Hawk.

I'm just speculating and drumming up interest since people asked me off line if it could be a Miss Kite x Swainson's hybrid. And it does resemble a kite but only in color due to the lack of pigment and whitish face. The bill seems small but just fine for Swainson's and I assume it is a male anyway since adult male Swainson's can have pale faces (but not to this extent of course) and the underwing coverts are pure white, which is much more common on males than females. But having said all that, I love hearing everyone has to say about it.

August 2, 2013 at 8:01 PM  
Blogger Bryce said...

Wow... Great photos of the bird. This is gold content Jerry. I love it.

My ideas are those of a student, not anything close to an expert, so feel free to shut me down or be blunt. What about schizochroism, lacking the pigment phaomelanin? From what I've learned lately in some reading, plumage aberrations are uncommon, but regular in birds. To me the bird looks normal for a SWHA, except for the color. It looks like there is an absence of all red/brown pigments in the bird, something like what a bird lacking phaeomelanin, only having eumelanin present, would appear. I saw Mia mention plumage aberration, and that seems like the best explanation to me. Fun to wonder though...

Here is the paper I read:

Great post as always.

August 3, 2013 at 12:04 PM  
Blogger Jerry Liguori said...

Hi Bryce

Yes, I definitely agree...and its such a striking bird for one that lacks color! The grayish belly and leggings are odd though

August 3, 2013 at 1:53 PM  
Blogger Bob said...

I would love to see a Picture of it soaring from directly below. On the first pic with its wings raised you can see a bit more darkness where the commas would be.

Whatever it is, I'd like to see it. Its a beaut.

August 4, 2013 at 9:36 AM  
Anonymous Cathy Sheeter said...

I added some additional photos from those I sent to Jerry to a facebook album. It is public so anyone should be able to view it. You can view them at:!/cathy.sheeter/media_set?set=a.10153079591525514.1073741828.602195513&type=3

Thanks for sharing these Jerry :)

August 4, 2013 at 11:39 AM  
Blogger Jerry Liguori said...

Thank you Cathy!

August 4, 2013 at 1:57 PM  
Anonymous Derek Lyon said...

Any conclusion as to what caused the odd plumage yet? Very distinctive bird, it's some kind of Swainson's, but the gray reminds me of a male harrier.

August 7, 2013 at 7:16 AM  
Blogger Jerry Liguori said...

Just an anomally like albinism, dlilutism, melanism, etc. I'm assuming.

Somebody might know the correct word to describe this bird.

August 7, 2013 at 4:51 PM  
Anonymous H.Gomaa. said...

Wonderful! Love these head-scratchers! From my perspective, I do see a Swainson's hawk, especially the dark bib. Very obvious in the 2nd photo. And the hand is long enough for Swainson's, the distance from the wrist to the tip of the primaries just surpasses the tail by a little bit just like in Swainson's hawks. You can see a little bit of the reddish brown in the greater primary coverts and even some on the axillary feathers at the arm pit. If you took the 2nd photo and ignored the colors completely and the length of wings, that bird almost looks like a red shouldered hawk, especially the head and the legs. Great find!

November 14, 2013 at 5:21 AM  
Anonymous Hatem Gomaa said...

I keep coming back to this birdie because it reminded me of another super rare raptor that was featured in a magazine many years ago. I'm guessing Jerry and some others remember this.
It has 'kinda' similar grey color appearance but in this case, it's a dilution of the bird's original color so it makes sense. But in this hawk here, the silver/grey is out of left field, for sure.

Interesting and somewhat similar yet different. IMO, probably one of the rarest birds in the world.
Adult bald Eagle with diluted plumage:

December 5, 2013 at 8:59 PM  
Blogger Jerry Liguori said...

I have seen that Eagle and a few others like it, very cool!

December 6, 2013 at 7:41 AM  
Anonymous Hatem Gomaa said...

Did you have any heart palpitations, or heavy sweating, or trouble breathing? The shakes? I know I would have all the above along with massive heart failure from excitement! Almost like maybe I should hope to never see anything like that. :)

December 7, 2013 at 7:57 AM  
Blogger Jerry Liguori said...

The first dilute plumaged bird I saw was at a hawk migration site when I was the counter. I identified it as a juvenile Red-tail on shape but it was silhouetted, I didn't see that it was dilute until it came by to my east, and I grabbed my camera and snapped two crappy photos with an old camera and slide film (bird I sent you). I was pretty excited to have it come by. The other observer was like "say that again, what the heck is that?"

December 7, 2013 at 8:01 AM  
Anonymous Hatem Gomaa said...

That's great. You mentioned above finding the right word to describe what's happening with this bird's plumage. It's interesting when you look a luecism or melanism vs dilution vs aberrant plumages and related species of raptors where one occurs more than the other or almost exclusively and vice versa. I think taking those terms and defining each one specifically to get a better understanding of them would probably be a better start. It would make for easier determination as to what is happening in each specific case. It seems leucism and melanism are the same thing? While dilution is something different as well as aberration (or aberrant plumages), those can be placed in a separate category and if it were up to me, I would put this Swainson's in the category of aberrant plumaged raptor. It has color, a lot of it, as a matter of fact, just not the typical ones. The color doesn't seem to be a result of albinism, leucism or melanism assuming all three of those are the same thing. It's not diluted because it's not a washed out version of the original/typical coloration because the pigment is very strong, just completely unusual for that species.

Off the top of my head (and correct me if I'm wrong, Jerry and/or others), but it seems like in red tails, you see luecism and albinism (or melanism, I guess) with the super rare and close to non-existent cases of dilution and no aberration. Whereas in some other species you see only dilution and others what appears to be combination of that and aberrant plumages almost and practically never any leucism or albinism such as bald eagles and that example I posted unless.....leucism and/or melanism is the same thing as dilution? I don't think there has ever been a documented case of albinism is bald eagles, has there? Red-tails seem to produce leucistic birds almost exclusively with exception of a super rare sighting like the one you just mentioned with dilution (which brings me back to thinking leucism is NOT the same thing as dilution). While birds like this Swainson's and certain other species produce almost exclusively aberrant plumages (besides color morphs which is something totally different)! Birds with extreme color morphs don't seem to produce any leucism and lean more towards aberrations. Even red shouldered hawks will show more aberrant traits than luesicm. Accipiters almost never of either. Same with falcons. At least that's what it seems to me and I think I'm more confused than when I started writing this.

December 9, 2013 at 3:23 AM  
Blogger Jerry Liguori said...

There are a few photos of leucistic and diluted Bald and Golden Eagles out there. Depending on who you ask and their reasoning, some say dilute plumage and leucism are separate things, some say dilute plumage is a form of leucism. I think there was a long discussion recently about it. Either way, it is nice to qualify which one it is no matter the definition

December 9, 2013 at 7:09 AM  
Anonymous Hatem Gomaa said...

I think common sense would suggest that dilution wouldn't be a form of leucism or connected to it in any way. One is basically the 'fading' (for the lack of a better word) of the color while the other is more of a color change. There is a clear difference and it seems to me pretty straightforward and very strange how anyone could correlate the two. I did see a recent photo of a partial albino rough legged hawk (the one I sent you) that made me think to never say never. How rare is any degree of albinism in rough legs compared to red-tails!? But then again, red tail populations are most likely greater so the chances are also higher. Interesting stuff.

December 12, 2013 at 6:39 AM  
Anonymous Hatem Gomaa said...

So what's your opinion, Jerry? Dilution same as leucism or separate from?
What about leucism and partial albinism? Putting you on the spot! :)

December 14, 2013 at 2:01 AM  
Blogger Jerry Liguori said...

It depends on who you talk to....there are some terms I don't gripe about and others I think need to be defined clearly. But terms like this everybody knows what you are talking about so its not a big deal. I have my preference but I really have no qualms

December 14, 2013 at 6:25 AM  
Blogger Ronnie said...

I have seen up to 9 of these amazing hawks near my house. Every time I clip one of my pastures they come and swoop down and catch grass hoppers flying up in front of the tractor. They usually get within 15 to 20 feet and are very beautiful and graceful. There seems to be 2 different sizes not sure which is male for female.

July 15, 2015 at 8:31 PM  
Blogger Jerry Liguori said...

Thanks Ronnie, and the females are the larger ones...must be fun to watch them!

July 16, 2015 at 6:09 AM  

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