Recently, I've had the opportunity to get some close-up views of a pair of Jays in my garden. I've noticed that they have different colour eyes.
This one has irises which appear brownish with a bit of a pink tinge.
Whereas this one has bright blue irises.
Is this just the normal variation similar to what occurs in humans or or is there some relationship to age, gender etc. or perhaps it's just a trick of the way the camera has rendered the image. Anyone know?
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Tony
My Flickr Photostream
I don't know. But while we wait for someone who does to come along, I can offer some conjecture...
I don't think it is a sex difference or a trick of the camera. It could be an age thing. All the pics I can find of fledgling and juvenile Jays show blue-grey eyes. Young Magpies also have blue-grey eyes, though darker than young Jays (nice photo here: http://m7.i.pbase.com/g9/82/46482/2/150905207.yeFst0RT.jpg), which darken to almost black with age, so there's a corvid trend there.
BUT I think there's a strong possibility that it's a general variation thing. You'd expect young Jays to have assumed adult eye colour by this time of year, as with Magpies (though I can't be certain of this). Also, Jays show lots of variation in a range of traits (including eye colour, which generally gets darker the further east you go) across their very extensive Eurasian range, and they are naturally rather mobile rather than sedentary. Although lots of Jay subspecies are described, the variation is basically clinal (changing gradually with latitude/longitude, with lots of moving about so lots of genetic exchange between populations) and some of the Jays we see, esp in winter, may well come from areas where darker eyes are the norm.
So my hypothesis at the moment is that all young Jays have slaty-blue eyes, and depending on their genetic mix some of them go on to develop brighter blue eyes with age while others develop brown eyes. Now we need to find some PhD student to go out and test it :)
My blog: http://mazzaswildside.blogspot.co.uk/
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Thanks for your thoughts, aiki. Your conjecture/hypothesis is most interesting and sounds very plausible. I'd never noticed the eye colour before but having looked back at some older photos I've found similar variations with some birds having brownish irises and others very blue irises. As you suggest a good subject for a bit of research.
Hi TJ, interesting about the eye variation. I've noticed that the youngsters appear to have paler blue than the adult Jays deeper colour which can have that pinkish hue around the edge, but then again I'm only going on the photos I have of the last two years adults and juveniles. I guess the different daylight can also play tricks too when combined with the camera lens and how it bounces off. The hue I've seen around the juveniles outer edge appears to be a more grey than pink/brown so maybe its an age thing ? Their eyes are so beautiful :)
Here's a few photos I grabbed from the hard-drive ...
Juvenile ...
adult with the browner/pinkish hue
same hue again ....
juvenile again - that slaty blue colour as Aiki says .....
pair of juveniles on a duller day where the eyes don't quite look so intensely blue
when you zoom in on this next one, the edge has a grey'ish rather than pink/brown hue
It's all rather confusing with their slightly different eye colouration lol ....... Maybe they are just like human variations !!
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Regards, Hazel