Yeah, Michael, the explorers worked their way across the continent usually from east to west. The eastern names were established first, and, of course, the big population centres remain largely eastern.
As a result, West Coast schoolkids to this very day know the commonest eastern bird names, but not their own. Children know such names as Ruby-throated Hummingbird, Blue Jay, Baltimore Oriole, and Red-headed Woodpecker, which predominate in text books and on cereal packages; but even adults remain fairly unfamiliar with our own Rufous Hummingbird, Steller's Jay, Bullock's Oriole, and so forth.
Of course, again, the books are printed in the population centres which are mainly eastern.
However, the influence is less now than it used to be. Peterson's first western field guide, in 1941, began the long slow process of "naming" our western birds for us. And I did enjoy eventually seeing the birds whose names I had known as a child--even though that experience came twenty years after the names themselves.
We also have quite a number of plants whose names are "False" this-and-that, as they were originally named for not-necessarily-similar eastern species. False azalea, False Solomon's-seal, and so on.
Hand-me-down names, that don't necessarily fit!
So you go for the junco/juncus etymology, do you? Pretty thin. Juncos have nothing to do with reedy places; they're especially non-reedy in the various habitats they choose. It's so easy for these people (not you; the etymology-writers) to make the connections after the fact, but I distrust surmise. The names junco and juncus are right on top of each other, but I still wonder.
(I got into the habit of debunking "native legends," which are almost all white-man's stories, years ago, when I was studying native cultures. I'm leery now. I'm not disagreeing with you; but I'm more comfy-cozy in my usual "I don't know" spot.
(We had such a problem in interpretation, getting staff to say "I don't know" instead of surmising, so it left me cautious. There was a fantastic example of wrong etymology circulated world-wide several years ago, as to the origin of "blue moon." Fascinating; but mildly horrifying, too. I believe it began with one person's [incorrect] surmise, and then the surmise being picked up in a schoolteachers' reference. Something like that.)
Do we have another bird named for a habitat it never visits? We have Magnolia Warbler, of the northern conifer forests. It has nothing particularly against magnolias, and I believe the first one gunned down was a migratory bird in a magnolia, very far to the south of what was until then its destination.
You know, Michael [and you do know, and I know you know; this is really for any readers who might find it interesting], the American and English Robins are dissimilar. But the bird that is much more confusing in its name is the Blackbird, singing in the dead of night--for your blackbird is a thrush. Not only is he a thrush, but he's a Turdus, of the very same genus as our American Robin. Therefore the American Robin and your Blackbird are much closer cousins than are the two "robins." And, if that isn't enough of a name-trap, we can top it off with the blackbirds here being members of a completely different family, not a bit closely related to your Blackbird.
Is that enough? Or should I add that the American Ornithologists' Union lists the American Robin, Turdus migratorius, and eight other Turdus thrushes as, in English, various kinds of robins; while listing another eight Turdus thrushes as thrushes. (There are more, but these all have adjectival first names, so the choice is there.) I guess fair is fair, right? Half and half.
All of this was done purposely, I'm sure. It just must be a conspiracy of some sort.
Tell you what, if you'd like to make a little trip down to Irazu, I'll go with you and we can look at Volcano Juncos together. Now there's a name that is right on! Our Zonotrichia sparrow collection of five is completed down there too, with Costa Rica's ubiquitous Rufous-collared Sparrow--the other four are right here.
I loved the Rufous-collared Sparrows, although I did not guess they were Zonotrichias. (That's an "oh, of course" thing.) There are wondrously few House Sparrows in Costa Rica, and the Rufous-collared Sparrows maintain their every-neighbourhood-has-some status, which is the way it should be. But I never visited the volcanoes, so, c'mon, let's go! Gotta see that junco!
A junco junket.
(Actually I aborted a to-be six-month CR trip last June, hours before plane time. I still have a ticket that is repairable for cheap, but I'm afraid my non-capitalist lifestyle barely buys me food, let alone flights of fancy.)