"Eye spots" on hawks

posted by Jerry Liguori at
on Friday, December 20, 2013 

Certain birds are known to have "eye-spots" on the back of their head, especially a few species of hawk and owl. I've heard several reasons why some birds have them, but would like to hear what others think about their function or purpose?

And, don't identify hawks by this trait alone…several of them can show it. It was believed years ago that it was a good trait for perched Rough-legged Hawks (below), but I have seen too many Red-tails (below) and a few other buteos show this. These are just a few examples, including this male Harrier (below) with a neat pattern they typically show. THESE SINGLE SPOTS ON SOME HAWKS REALLY DON'T RESEMBLE EYES, but just wanted to make a point.

 Rough-legged Hawk

 Red-tailed Hawk

 Northern Harrier
Anonymous Ron Dudley said...

Jerry, Just a couple of observations from a rank amateur. I guess I never thought of the single, central spots on the backs of the heads of hawks as eye spots. I've often wondered about the rusty spot on the male harrier in particular and I've tried to look it up and struck out (even BNA in their extensive description of "definitive basic plumage" doesn't mention it). I guess I've always thought of the double spots on the back of the head of kestrels as more like "eye spots". Any thoughts? (I'm here to learn...)

December 21, 2013 at 6:19 AM  
Blogger Jerry Liguori said...

No, I agree with you Ron, I don't consider these eye spots but just wanted to bring attention to the fact that birds have been identified by this spot alone and it is dangerous to do so. What do you think the eye spots on Kestrels and Pygmy Owls serve? I've heard theories but want to hear what people have to say.

Also, watch out for the term "definitive basic plumage", this term is misleading in regards to many birds, but accurate for others

December 21, 2013 at 7:14 AM  
Anonymous Ron Dudley said...

I've heard some of the same theories, Jerry but in the case of kestrels and Pygmy Owls I'm unconvinced (though it is possible). I think similar "eye spots" found on the rear of the body of some other animals (certain insects, for example) make more sense as a "head decoy" so the potential predator goes for the "wrong" end and allows the potential victim to possibly escape or defend itself. Who knows, though...

December 21, 2013 at 7:33 AM  
Blogger Jerry Liguori said...

Exactly Ron....

December 21, 2013 at 7:47 AM  
Anonymous Matt Finch said...

For a predator that is fearful of anything directly behind them and is hardwired to react to what they see, and is constantly looking around and behind it, I don't think "eye spots" serve any purpose at all. As a decoy, or identification. They don't even look like eyes. I agree with you guys in saying that trying to identify a raptor based on those spots is futile. Its like trying to figure out what falcon you're looking at by looking at a silhouette and wing shape alone. But it's an interesting trait that raptors share. Its like black wingtips on almost every species of North American Raptor,(btw I know why they're black but that's a different subject) but to try and guess what purpose "eye spots" have is a waste of my energy in my opinion.

December 21, 2013 at 10:27 AM  
Anonymous Jane Driscoll said...

Thank you Jerry, enlightening since I've never seen a Red-tail with that spot that I associate with Rough-legged Hawk.

I learn so much from your blog, thank you.

December 24, 2013 at 3:19 PM  
Blogger Jennifer Bunker said...

I have often wondered about these "eye spots" especially in Roughies. And, dare I admit that on more than one occasion I have had to take an extended period of time to decide if a Kestrel is actually looking at me, or looking away, or looking left, or right or ...? Each time this has happened I have been a long distance away looking through a camera lens. Because of this I have always thought the "eye" serves some kind of decoy purpose to other animals who might spot the bird from a long distance away. Up close, we all can see that it's not an eye, but from far away, it's harder to tell. For what purpose this is, I don't know, but I have always thought this "eye" had something to do with distance. Just my .02!

December 30, 2013 at 4:50 AM  
Blogger Jerry Liguori said...

Thanks Jennifer, and that is one of the theories behind the eye spots, that predators believe the kestrel can see them. And I think that's a good theory for the smaller birds like Kestrels and Pygmy Owls

Please keep commenting whenever you want!

December 30, 2013 at 10:44 AM  
Blogger Thomas Dixon said...

I've heard the eye spots also referred to as "ocelli," and, because they are found on smaller raptors, assumed that they functioned strictly in warding off predators. Negro et al. (2007) (link below) present some interesting alternative hypotheses, but I'm not sold on their conclusions.

January 11, 2014 at 11:29 AM  
Blogger Jerry Liguori said...

Thom -- Thanks for the link to the paper. Cooments like this are great and the prurpose of my blog!

January 11, 2014 at 3:41 PM  

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