eclipse plumage, etc.
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Ted Floyd
May 2, 2026, 3:11:10 PM (17 hours ago) May 2
to Colorado Birds
Hey, all.
First off, thanks for the great Mexican Duck conversation. The take-home message, at least as I am receiving it, is: Let's get out there and document Mexican Ducks, candidate Mexican Ducks, Mexican–like ducks, and whatnot. Brilliant. Bring it on. Together we'll advance our knowledge of the status & distribution of diazi genes in Colorado.
With that out of the way, this, from Tony:
"Finally, a little bit of a deviation from the subject: A plea to birders to quit using the phrase 'eclipse plumage.' Ducks are no different from all other Colorado species in conducting a substantial molt as adults after breeding. There is no reason to call the post-breeding molt of Mallards one thing and that of Yellow-rumped Warblers... and Spotted Sandpipers, Bobolinks, Swainson's Hawks, California Gulls, and Lazuli Buntings another thing. The only real difference is that ducks hold that 'Basic Plumage' for a much shorter portion of the calendar year. But it's the same molt.'"
So, unless there's been a big recent disclosure that I'm not aware of (could be!), that's not right. It's *not* the same molt. Contra everything we were taught in the benighted 20th century, the "dull plumage" (Tony, I'm doing your bidding, but see below 😈) in most Colorado ducks, is in fact the *alternate* plumage. Not the basic plumage. Here is a link to Peter Pyle's seminal 2005 paper on the topic:
birdpop.org/docs/pubs/Pyle_2005_Molts_and_Plumages_of_Ducks.pdf
Okay, now let's talk about that "dull plumage." The eclipse plumage. (Leukering prepares to commit self-defenestration...) If I'm hearing Tony right, I fully & completely agree with half of what he is saying, viz., that it is an excellent idea to understand molts & plumages. For starters, it's pragmatic: Such knowledge can be valuable in identifying birds to species. It is also essential for even beginning to attempt to age birds correctly. (Which, to complete the circle, brings us back to species-level identification. Because you can't identify summer dowitchers in Colorado without first knowing how old they are, which requires an assessment of molts & plumages).
First off, thanks for the great Mexican Duck conversation. The take-home message, at least as I am receiving it, is: Let's get out there and document Mexican Ducks, candidate Mexican Ducks, Mexican–like ducks, and whatnot. Brilliant. Bring it on. Together we'll advance our knowledge of the status & distribution of diazi genes in Colorado.
With that out of the way, this, from Tony:
"Finally, a little bit of a deviation from the subject: A plea to birders to quit using the phrase 'eclipse plumage.' Ducks are no different from all other Colorado species in conducting a substantial molt as adults after breeding. There is no reason to call the post-breeding molt of Mallards one thing and that of Yellow-rumped Warblers... and Spotted Sandpipers, Bobolinks, Swainson's Hawks, California Gulls, and Lazuli Buntings another thing. The only real difference is that ducks hold that 'Basic Plumage' for a much shorter portion of the calendar year. But it's the same molt.'"
So, unless there's been a big recent disclosure that I'm not aware of (could be!), that's not right. It's *not* the same molt. Contra everything we were taught in the benighted 20th century, the "dull plumage" (Tony, I'm doing your bidding, but see below 😈) in most Colorado ducks, is in fact the *alternate* plumage. Not the basic plumage. Here is a link to Peter Pyle's seminal 2005 paper on the topic:
birdpop.org/docs/pubs/Pyle_2005_Molts_and_Plumages_of_Ducks.pdf
Okay, now let's talk about that "dull plumage." The eclipse plumage. (Leukering prepares to commit self-defenestration...) If I'm hearing Tony right, I fully & completely agree with half of what he is saying, viz., that it is an excellent idea to understand molts & plumages. For starters, it's pragmatic: Such knowledge can be valuable in identifying birds to species. It is also essential for even beginning to attempt to age birds correctly. (Which, to complete the circle, brings us back to species-level identification. Because you can't identify summer dowitchers in Colorado without first knowing how old they are, which requires an assessment of molts & plumages).
That said, I don't object to the term "eclipse plumage." We have all sorts of taxon-specific phraseology like that. Hawks have eyries, and herons have rookeries; but we we don't have similar words, as far as I am aware, for the nests of shrikes and blackbirds. Formative kittiwakes are tarrocks, and fledgling turkeys are poults; but we don't have similar words for, say, loons and woodpeckers. The progeny of Callipepla squamata x C. gambelii are Scrambled Quail; but we don't have an analogous name for the hybrid young of presumptive Mourning x MacGillivray's warbler pairings. Words like eyrie, tarrock, and Scrambled don't get in the way of understanding "nest," "formative," and "hybrid," and I don't think "eclipse" gets in the way of understanding that the dull plumage of most Colorado waterfowl is, surprisingly, the alternate plumage.
Ted Floyd
Ted Floyd
Lafayette, Boulder Co.
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