Identification flip flop: The grebe that changed species sides

I guess I am really trying to pin a species name on this Harris Co. bird, very typical of most birders and I figure if I put my neck out there at least others have something to criticize. Yes at this point it seems the safest bet is to jump on the Western/Clark’s fence for this one and just wait were the balanced opinions of others will fall. Yet the fence position is a bit too safe for me so I will again reverse my opinion and say that this bird tends towards Western, but I am not sure. It definitely is an intermediate that defies easy identification, it literally has two faces, and the possibility of a hybrid is difficult to rule out with certainty. After studying my observations and the photos further I compiled a table summarizing what I have so far with a strong dose of my opinion thrown in. This is a great bird to learn from and may end up in the Western/Clark’s category.

Character

Reliability

Western

Clark’s

Likelihood Western much more likely east of its range Many more records east of range X Fewer records
Dark around eye Changes from winter plumage to breeding, with possible overlap in winter Harris Co. bird looks good for Western on right, dark feather may just be coming in due to molting from winter to summer so good for Western X X Looks good for Clark’s on left, dark around eye may be a shadow due to head feathers good for Clark’s, BUT dark extend down to top of eye not that good for Clark’s at least in breeding plumage
Bill color Apparently reliable during most time of the year and utilized as a significant field mark Depending on angle and light the bill varies from slight greenish yellow to bright yellow, both OK for Western X X Pictures showing yellow bill support Clark’s, BUT not orange/yellow, also bill appeared quite bright in field, also good for Clark’s
Bill size/shape Overlap Looks better for Western X Looks somewhat heavy for Clark’s
Neck stripe Thickness apparently variable Broad and dark supporting Western X Seems too wide for typical Clark’s
Back color Variable in the pictures we have In the majority of pictures and during field observation appeared dark, same color as crown and neck stripe supporting Western X x Appears too dark for typical Clark’s but due to light variation and general variation this is difficult to judge
White on flanks Appears variable Limited but seems to fall within range of both species, but tending towards Western X Not as extensive as typical Clark’s
Size Western  tends to be larger Not possible to judge X X Not possible to judge
Call Maybe reliable NOT HEARD NOT HEARD
Experts  hybrid has also been suggested X
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One response to this post.

  1. the only rational path forward is just to declare it a new species. Aechmophorus lorenzi?

    Reply

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