Many animals and birds have striking markings around their eyes, made of fur, feathers or just plain skin. Why?
Pale circles round the eye may help gather extra light for animals that feed in reduced light. Dark circles around the eyes may reduce glare for animals that feed in bright light. Often, though, these markings have no precise function. They either disguise the eye, or break up and confuse the head contours, or aid in species recognition. Here are some examples.
The American red squirrel has elegant white semi-circles above and below its eye, probably helpful in noticing predators when feeding in dappled light:
Raccoons famously sport dark highwayman’s masks, but it seems unlikely that reducing glare is their main function, since raccoons are largely nocturnal:
Wood frogs too have dark masks, and they live mainly in thick woodland, where the light is not bright. (Though the dark lines in front of the eye may help in accurately targeting prey.)
But the Southern Masked Weaver’s dark mask may indeed be an adaptation to reducing the glare of the Namibian desert:
And the Egyptian Goose, although this one now lives in Hyde Park in London, originates from Africa and so its dark eye circles may not just be the result of a late night out, but may have given it an edge in that bright light:
My last few examples are almost certainly not aids to vision of any kind. Just like our eye makeup, they may serve to attract a mate. Whatever works for you…
In Maine, the wood doves have pale blue eye-liner: a look I am considering for next summer.
In Ecuador, both the male Masked Trogon (first photo) and the female (second photo) wear red-rimmed spectacles:
As does the Zambian Three-banded Plover:
Here in the UK, the common blackbird has sharp yellow circles:
But these are outdone by the Ecuadorian the Cock-of-the-Rock’s astonishing yellow goggles:
Finally, by popular demand, the Plate-Billed Toucan: not exactly an eye ‘ring’, but the most flamboyant choice of eye shadow shades that I know:
Humans need more help:
[James Charles is sponsored by Covergirl. He is the beauty blogger phenomenon who stopped traffic in Birmingham last week. ].
If you’d like to know more about natural eye makeup, read this:
Ficken, Robert W., Paul E. Matthiae, and Robert Horwich. “Eye marks in vertebrates: aids to vision.” Science 173.4000 (1971): 936-939.
PS There is a separate story about the color of the eyes themselves. Maybe I’ll look at that next.