DLecy

The loads of literature on dowitcher ID supports the notion that they are anything but obvious, especially in winter and after the breeding season, and of course, when silent. https://www.labirders.org/assets/images/webinars/JDunn_DowitcherID.pdf https://www.birdwatchersdigest.com/bwdsite/podcast-episode/spotlight-episode-111-identify-yourself-you-can-do-dowitchers-by-alvaro-jaramillo/ As for size, Sibley states they they are identical in wingspan and weight, and are 1 cm different in length. Since there is also variation within species, size is an unreliable field mark.

These birds cannot safely be identified to species based on the photos provided. Dowitchers are almost identical, and are most difficult to ID after the breeding season (right now, when they are worn) and in the winter. They are easiest to ID visually in the spring and if they are juveniles, which I don’t see any of in your photos. Unless you heard them call, at this distance, they should be left as SBDO/LBDO. The names “short-billed” and “long-billed” are VERY misleading as there is considerable overlap in bill lengths. Likely, only the very longest-billed female LBDOs, and the very shortest-billed male SBDOs can be identified with any level of confidence. And even then, a combination of field marks should be used. As has been stated before, the most reliable way to ID the two species is by voice.

Based on location, this is a Vaux's Swift.

GISS is Pomarine, IMO. It’s stocky and barrel chested. Where in Alaska? It’s a pretty big place.

This first bird is almost assuredly a female/immature BCHU. There are only 2 records for Costa's at Big Bend, which is birded quite well. https://macaulaylibrary.org/asset/247074761 The shape of the primaries, especially the narrow inner primaries (among other things), easily rules out Broad-tailed in the second bird. Compare with BTHU. https://macaulaylibrary.org/asset/162407261 https://macaulaylibrary.org/asset/109327211

I wouldn’t call the first bird since we can’t see the tail or wings. The second is a Black-chinned Hummingbird.

This does not distinguish the bird from a Ruby-throated Hummingbird, which can and does appear black-headed when not seen in the right light. Females of the two species are extremely similar. What clinches the ID here as a BCHU is the shape of the primaries, specifically the clubbed outer primary(P8) and the inner primaries, which are more rounded than a RTHU.

Coop.

HOFI from yesterday. https://macaulaylibrary.org/asset/357033291

Seems fine for juv. ANMU. Marbled would (typically) look much different a month ago.

Likely all LBDOs.

https://macaulaylibrary.org/asset/232516461

I concur that BASA is the only other real possibility here. Structurally, the bird feels better for a Baird’s, but the front end looks like a SESA to me. The bill is consistent in a number of the shots, leading me to believe that’s actually how it looks. I still lean SESA here, but could also see how this may be a BASA.

Ah, I see. So it's not a rarity. A lifer is on the line. I get it. Just as important, if not more so. I think it looks like a SESA and there were two there the day before. It's your life list and your call...Good luck!

I know you are worried about your reputation, and I totally get and respect that. As someone who advocates for slashes and "spuhs" all day long, I will definitely admit that being too conservative on an ID has its downside. If you get on a good bird that others might want to see, and you report it as a sp. or slash, it never gets out there (in eBird terms) unless you post separately on a listserve or Whatsapp group etc. For example, last year in my county someone found a Bar-tailed Godwit but didn't report it until someone else found it 5 days later. In those 5 days the original finder sat on it and didn't report it, many people could have gone to see a bird that is a CBRC Review Species and a great county bird. Instead, a handful of people chased it and some got it, while many others didn't. With regards to your bird, you could always post it in eBird wit the caveat that you are working on the ID but feel as though it's a solid candidate for SESA and you wanted to get the word out there. People will respect that, and appreciate it if you found a good bird, even if it turns out to be something else. At least you are trying to get the word out there for others in your local birding community. I realize you particular bird might not be chaseable, but this is a lesson that can be applied to any mid-level rarity on up. Hope that makes sense. I still think your bird is a strong candidate for SESA.