Head and shoulders
Well I did say earlier that I prefer portraits to groups. As this Oystercatcher agreed to a short shoot I took the opportunity eagerly. Whilst I do wish she’d brushed her ‘teeth’ before posing I think red, greens and black look quite nice. You can of course still think what you like, that’s your prerogative, despite what the BBC tells you what to believe.
Now, this picture shows something that I, at least, find extremely interesting. Look at the pupil of this bird, it doesn’t appear circular, in fact it almost looks elliptical. If this was so it make the birds vision crap. Something hardly likely to persist in a world where being eaten any minute of every day is a real probability. There is a reason why pilots have to have the highest visual acuity. Birds can see, trust me on this. We can discuss their intelligence later if you wish, but not their eyesight. Birds with my eyesight finish up in a cat’s (or similar) tummy PDQ.
So what is going on. It might be better to describe it as looking like the black pupil is ‘bleeding into’ the red of the iris. Well, the actual reason for this is that some pigment in the outer surface of the iris has faded or thinned allowing the black inner structure of the iris to become visible through it. This inner surface ‘has’ to be black of course otherwise reflections within the eye itself would ruin eyesight, cat’s tummy, yum yum, that sort of thing. Yeah, great Sherlock, but WHY do these ‘eye-flecks’ occur in some birds. Well …………
………….. can we talk about sex now please, well sexual dimorphism to be exact: the phenomenon that the males and females of many species, inc birds, appear very different, think most ducks for example, whereas in many other species they are essentially the same. Now, we can throw ourselves into the world of ‘adaptive story-telling’ as ecologists /evolutionary biologists call it. The question is, for what is it worth, how do boys and girls tell each other apart if they are identical in appearance. Yeah, easy for a duck right, but what of a pigeon or, yes, an Oystercatcher. Male and female are visually identical, so how do they avoid mistakes on those nice romantic beach picnics. ………….
………..now we go into storytelling overdrive ……….Guzzetti et al. (2008) reported that these eye-flecks are predominantly only identifiable in the females of Black Oystercatchers. Bringing a true meaning to the phrase ‘look into my eyes darling…..oops. nope, sorry mate’. So is this all true? I mean it is in a scientific journal right. Well it is for sure, whatever trust we pay to such stuff today. Look, I like it, but it has some methodological weaknesses, in fact quite a lot. Looking though the hundreds of images of oiks I have, well I cannot find a single male according to this idea, and all the couples I have are, well, lesbian. So who knows, I have an opinion I really do. I’ll tell you sometime.