Three days ago I found 3 horned grebes on a large wetland in central St. Louis County. Each was sporting a different plumage: one was clearly still in breeding plumage, a second appeared to be transitioning to winter basic plumage, but the third one was a puzzle--no "horns," and an all darkish (but not as dark as breeding plumage) head with the only evidence of differentiation between the upper half of head and cheeks a pure black line extending in back of the eye, and with a brownish-white foreneck. I'm trying to figure out if this might have been a first-year bird, which are described as having "duskier" heads than the winter basic plumage. One clue may be eye color. It had the bright red eye of an adult. Does anyone know when first-year horned grebes acquire this iris color? Also, I'd be interested in discussing the finer points of this observation with anyone who has extensive experience with horned grebe plumages, especially formative (first fall).
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