Monday 4 November 2019

[cobirds] SBDO or LBDO, Douglas County

Struggling a bit with a species ID.  Had a suspected juvenile Short-billed Dowitcher and female Long-billed Dowitcher (molting juvenile) at the Plum Creek Delta at Chatfield SP on Sunday.  Overall, I have a strong impression that these birds are not the same species, but I could be convinced that I'm looking at a female and male LBDO.  Would appreciate any input.  Checklist link, notes, and photos below.

John Haycraft
Denver, CO

Link to checklist: https://ebird.org/checklist/S61181228 

Checklist notes on the suspected SBDO:
Not 100% confident on the SBDO call, but we do feel confident that the larger bird (with longer bill) is a female LBDO in Autumn molt. Neither bird appears to be in winter plumage.
Molt may have just begun for the suspected SBDO. Upper back in ML186040291 and ML186040321 appear to be more consistent with non-molting SBDO juvenile, but molting is shown in ML186040381 and ML186040391. Bird is slightly smaller in all pics (not sure that's informative given that sex is unknown); has more reddish tint at throat; has less/weaker markings on sides; has darker tail (molting LBDOs appear to have grayer tails); has extensive white underneath (but this doesn't exclude molting juvenile LBDO). Internal bars/stripes on tertials are not observed but we found bird app photos of SBDO juveniles that also do not show SBDO bars/stripes on tertials.

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