Hey! My eyes are up here!

The exact kind of post that has inspired some people to call me the "Dr. Ruth of Ornithology"

(Listen to the radio version here.)

One of my firm beliefs, based on all kinds of data, is that birds are superior to humans in countless ways, from their ability to fly and the higher altitudes they can easily negotiate without supplemental oxygen to the broader spectrum they can see and the wider range of sound frequencies they can hear.

In many ways, birds are also luckier than humans. The only time a bird ever obsesses about its reflection is when it doesn’t recognize the image as itself and tries to drive away the perceived intruder.

That may not seem very lucky for a robin or cardinal endlessly attacking someone’s window or car mirror, but think about what humans have done over the millennia as we’ve obsessed about our own mirror images. You’ll never find a bird binding its feet to keep them tinier than they’re supposed to be, elongating its neck with increasing numbers of metal rings, sucking fat out of one part of its body to infuse into another, injecting dangerous nerve toxins into its face, or undergoing potentially life-threatening surgeries, all for no other reason than to change its natural appearance.

Birds recognize one another as individuals, and when they’re displaying in a competition for a mate or territory, they do focus on appearances, but they don’t stare, at least not in a way that makes them uncomfortable. No bird has ever had to tell another, “Hey—my eyes are up here!”

Well, okay—sage grouse of both sexes DO stare at the chests of displaying male sage grouse. But this is actively solicited, no one takes offense (except some prudish humans—go figure!), and for the vast majority of the year, they don’t think about sex at all.

I’ve been thinking about that this week after looking at some woodpecker photos and thinking about how the important features that distinguish individuals are concentrated on their faces and heads, so of course when they’re staring at each other, they’re making eye contact, too. Just about everything a woodpecker needs to know about another is visible when that other woodpecker peeks out of its nesting or roosting cavity. From the time a baby Pileated Woodpecker grows its first feathers, males have a red forehead and mustache mark while in females these features are gray or brownish black.

Adult male flickers have a red or black mustache mark that adult females lack.

Both male and female Red-bellied Woodpeckers have a brilliant red nape, but it extends all the way forward to the beak in males, giving them a red crown and forehead, which females lack.

As far as we can see, Red-headed Woodpeckers lack sexual dimorphism, meaning that, at least to our limited human eyes, males and females are identical. But they may look far different to one another because their eyes perceive a wide range of colors that we’re blind to.

We know that many woodpeckers, including Red-headeds, see within the ultraviolet spectrum. Studies show this helps them to detect certain tree fungi. Fungi are hardly a significant part of a woodpecker’s diet but may be useful indicators of rotting trees that support food in the form of insects and shelter in the form of softened wood for excavating.

The ability to see in the UV spectrum may well have another use for woodpeckers. Until recent decades, we had no clue that the plumage of a great many birds can absorb or reflect UV light detectable to other birds. Newly molted Northern Saw-whet Owl flight feathers glow pink when we shine a blacklight on them.

This photo from Jim McCormac’s excellent blog, “Ohio Birds and Biodiversity,” shows how the newer flight feathers are very pink, fading as the feather gets older. The molt pattern helps bird banders age these tiny owls.

Bird banders use this special lighting to see a saw-whet’s molt pattern to figure out how old the bird is. But is that UV reflectance useful for the owls themselves? The more sunlight this nocturnal bird is exposed to, the more quickly the porphyrins that cause UV reflectance degrade and the more quickly the UV color fades. So saw-whets may judge one another’s fitness as potential mates and providers in part by how much the feathers reflect UV light: the richer the color, the less sunlight the bird has experienced, so the better it might be at locating and defending cavities. This is my own speculation—I haven’t read any studies that confirm this, and the owls aren’t talking.

Most Black-capped Chickadees appear virtually identical to our eyes—bird banders can distinguish males from females in the hand only during the breeding season, and only if they see a cloacal protuberance if it’s a male…

…or a brood patch if it’s a female.

Hidden under her belly feathers, a nesting female chickadee’s brood patch is gigantic. Her hot, bare skin must be in contact with all of her eggs to evenly incubate them, and a typical clutch may have 6–9 eggs!

Chickadees themselves can see individual differences without inspecting one another so crudely and rudely. I do believe I’ve heard more than one chickadee muttering to a bird bander, “Hey! My eyes are up here!”

We mere humans cannot determine the sex of Red-headed Woodpeckers by a brood patch because both sexes incubate their eggs, and the cloacal protuberance isn’t always evident in breeding males. Except during mating, the sex of most birds doesn’t matter to them anyway—they’re perfectly content using they and them as their pronouns.

I haven’t been able to find any published information about whether woodpecker feathers reflect UV light, but I can’t help but think they must, based on the fact that they can see in the UV spectrum. As striking and beautiful as Red-headed Woodpeckers look to us, it’s thrilling to imagine that they are even more brilliant and colorful to one another.