Looking out in the backyard I was watching one hunt for worms and was struck by the red breast covering almost the entire ‘underside.’ I did some googling and found some ‘expert’ pages that said “I dunno”
So I thought I’d ask someone really knowledgeable…
As with a lot of bird coloring and other plumage decorations (e.g. the tails of peacocks and Quetzalcoatl) the answer boils down to what the opposite avian sex finds attractive.
That would work if the females were strikingly less fancy, but the female robins I’ve seen lately (I can tell they’re females because they are plump with eggs) hve breasts nearly as orange as the males. I guess it’s like mens nipples.
As for the color being orange, not red, I’ve heard that in some cultures there is no word for some of the secondary colors; the name just defaults to the closest primary. This could explain why “redheads,” whose hair color is decidedly orange, or ginger, color, are not called “gingers,” at least in the US.
To add something factual to the topic… An interesting thing about feather coloration is that some of the coloration is not due to pigmentation, but rather to the structure of the feather itself (scattering and reflecting light.) Greens, blues, and violets are most often the method for achieving this effect. Other color shades are more often created by pigmentation.
In the case of oranges and reds, the pigmentation is caused by carotenoids. Why this is relevant is possibly explained by this Wikipedia quote:
Bolding added.
So a guess would be that where robins flourish, there is a food item that is a good source of carotenoids.
I think the breast of British robins is closer to red; this may have influenced the perception of the bird that was to become the American robin. The British robin isn’t very closely related to the American one so it’s interesting that in both birds the females also have the ‘red’ breast.
Correct me if I’m wrong, but I think the American robin is closer to the blackbird, in which only the male has striking colouring. Most other thrushes have fairly dull colouring in both sexes.
But British / European robins flourish pretty much anywhere, alongside birds which have little to no red colouring. I think American robins are widespread as well.
Hazy memory from this being explained at school (or Sunday school)
Jesus (or a saint) was in a cave trying to keep warm with a small fire but failing … the robin came along and fanned the fire with his wings to keep it going and saving the life of Jesus/random saint but either he got too close or the flames suddenly got really hot 'cos he burnt his breast and that’s why it’s red.
Another legend says that a robin tried to pull the thorns from the crown of thorns out of Jesus’s brow. A drop of Jesus’s blood stained its breast and that’s why it’s red.
We’re not called gingers because ginger isn’t orange. Not even remotely orange, neither when raw or ground. Do they have a special sort of not-tan/brownish ginger in the UK?
Different paths. Just because one guy uses caretenoid (presuming that to be the source for robins) to show off doesn’t mean the next guy over can’t use a big set of tail feathers.
Back in parochial school I was taught that a robin’s breat was red because you could see the blood through it’s skin. No joke.
That’s the day I stopped paying attention to what they taught me in Science class there.