Eye Shine and Owlet Nightjars

To: Chris Corben <>
Subject: Eye Shine and Owlet Nightjars
From: Graeme Chapman <>
Date: Tue, 19 Nov 2013 12:48:26 +1100
Hello Chris,

Thanks again for your interesting and detailed response.

Now that you mention Jack, he gave a fascinating lecture on this subject to the 
folks at O'Relillys Bird Week some years ago - I have but a vague recollection 
of the detail - such is the joy of getting older!

I do have a good picture of a Tawny Frogmouth in staring mode - I should 
annotate it appropriately.



On 19/11/2013, at 9:41 AM, Chris Corben wrote:

> Hi Graeme
> There's an interesting aspect to this. The man to talk to is Jack Pettigrew, 
> who has done a massive amount of work on the eyes of these creatures. I know 
> he looked at Owlet Nightjars, but am not sure what he found.
> But because of my long involvement with Frogmouths, I do remember the story 
> with them. They are apparently at least unusual in being able to swivel the 
> eyes within their sockets. I thought Jack said this was very unusual in 
> birds, but am not sure. But the case with Frogmouths is quite fascinating.
> Because they can swivel their eyes, they have two different modes of vision. 
> In one mode, the eyes look out to the sides and then there is very little 
> overlap, so their sight covers a very wide angle but without the bifocal 
> overlap which gives a sense of depth. Like the vision you would expect of a 
> Snipe! So this is well suited to looking for threats, but not for catching 
> prey. In the second mode, the eyes swivel around to face the front, giving 
> them a much narrower field of view but with broad bifocal overlap and good 
> sense of depth. More like a Human or an Owl.
> If you watch a roosting Frogmouth in the daytime, you can see these modes 
> very easily. Typically, a roosting Frogmouth perches in a very relaxed 
> position, sort of like a Kookaburra in general pose. I am convinced they 
> never sleep - certainly I have seen no evidence of it. They are constantly 
> alert. If they see what might be a threat, they then strike the classic 
> "broken branch" pose, where they stretch out their body and slim it down so 
> it looks smaller and less conspicuous. In this pose, they watch you through 
> one eye, looking out sideways at you and reducing the eye to just a slit, 
> which isn't very conspicuous, and I think is the reason people think they are 
> asleep - because the eye looks shut.
> If you then walk around them, they follow you with very inconspicuous head 
> motions - keeping you in view with one eye. But typically there will come a 
> point where they suddenly turn to face you, swivel their eyes around and 
> stare straight at you with both eyes, at which time they take on a look which 
> is much more owl-like!
> I don't know if an Owlet Nightjar can swivel its eyes.
> Cheers, Chris.
> On 11/18/2013 03:29 PM, Graeme Chapman wrote:
>>> Hello Chris,
>>> Thanks for your interesting insight.
>>> Ref the eye-shine thing I'm attaching a close-up which shows the angle of 
>>> an Owlet-Nightjars eyes ( pic 317201 on my website) - they appear to me to 
>>> point largely to the side and also appear to very convex - quite odd 
>>> looking really and it looks as though their peripheral vision might even 
>>> allow them to look a long way behind them. Using a spotlight I suspect it 
>>> wouldn't be easy to see both eyes at once. What do you reckon?
>>> Cheers
>>> Graeme
> -- 
> Chris Corben.


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