Darwin & Inkgleam
Inkgleam
Have you ever noticed how a robin’s bright red breast looks like a bruised sunset, as if the color is arguing with itself? I love to sketch that tension, but I wonder if you ever write down those arguments in your field notes, Darwin?
Darwin
I did jot down the robin’s red breast in my notebook labeled “RB‑07.” The hue shifts about five per cent between dawn and midday, which I recorded as a 0.12 reflectance at 560 nm at sunrise, rising to 0.18 by noon. That fluctuation is my hypothesis that the colour toggles visibility to predators and mates, a balance of survival and attraction.
Inkgleam
That’s like painting a color that changes its own mood—so sweet! I’d doodle the robin with a little clock over its chest, each tick a splash of brighter paint, so the bird feels every sunrise and noon shift. Makes the feather a living mood ring, right?
Darwin
I logged the robin’s “mood ring” in my notebook—RB‑08. I measured the red at three times: 18:00 0.14 reflectance, 12:00 0.18, 06:00 0.12. The shifts match the hormone levels I track for molt timing. So yes, the feather is a living mood ring, and I record each tick as a data point to prove the theory that colour signals fitness to both predators and mates.