Oman non-breeding Terns (also Gull-billed & Bridled) -- Masirah Island & Musandam (1 Viewer)

[AFM]

I have been seeing these terns with black bills and partially black heads (first 5 photos) all over Oman and I think they are non-breeding Common Terns but could also be White-cheeked, Whiskered or Roseate Terns. These photos were all taken between April 20-24 on or near Masirah Island, Oman. Photos also include a Little Tern and a Greater Crested Tern, for size reference.
Then there is a photo of a very similar looking tern but you can see by the Lesser Crested Tern next to it that it is actually much larger. I am assuming it is a Gull-billed Tern transitioning into breeding plumage because I don't see the yellow tip characteristic of Sandwich Terns, but I am unsure.
Finally, some pictures of what I believe is a Bridled (not Sooty) Tern taken this morning (April 25) in Khasab Musandam in the Strait of Hormuz (Omani Exclave near UAE). Back seemed to be more gray than black and white forehead seemed to extend past the eye, hence my guess that it is Bridled not Sooty. But Terns are definitely not my strong-suit so wanted to get others' opinions on this!

 

[AFM]

Here is also an eclectic mix of flying tern photos with partially black heads, but I don't remember the size of these particular individuals which may make them harder to ID. They are also likely not all the same breed. All were taken near Masirah Island on April 23.

 

[Butty]

When were out-of-plumage terns ever not a Big Problem...
Pic 1, 3rd from right + pic 2, front row, 3rd from left (same bird?) - near-breeding white-cheeked tern?
Pic 2, just below right of centre, head down - bridled tern?
Pics 3-5, all except the greater crested/swift tern - common terns?

photo [pic 6] of a very similar looking tern but you can see by the Lesser Crested Tern next to it that it is actually much larger. I am assuming it is a Gull-billed Tern transitioning into breeding plumage because I don't see the yellow tip characteristic of Sandwich Terns, but I am unsure.

Can't see this as a gullible tern - and it should be a bit smaller than the lesser crested tern, not bigger. I'd easier see it being some odd plumage/bill-colour of lesser crested.

Finally, some pictures of what I believe is a Bridled (not Sooty) Tern

Not posted.

 

[THE_FERN]

your "gull-billed" looks like sandwich to me. Its back is slightly lighter in colour than the lesser-crested next to it [to my eyes] and its bill is the right shape. Flight feathers are perhaps darker than expected but not impossibly so.

 

[AFM]

Thank you so much Butty! I'd seen you post on similar questions and was hoping you might be able to help

Pic 1, 3rd from right + pic 2, front row, 3rd from left (same bird?) - near-breeding white-cheeked tern?

Oh yes I had noticed the gray plumage and wondered about that! It is the same individual, and I have another photo of it in a different pose that I'll add too, in case that helps.

Pic 2, just below right of centre, head down - bridled tern?

I have two more pictures of that tern that I can attach as well (with the White-cheeked Tern on the left side). Sadly it is preening in all my photos, so a bit hard to know!

Pics 3-5, all except the greater crested/swift tern - common terns?

Okay that is a relief, that was my guess too but it's always good to have a second opinion. Not a new bird for my life list anyway so the stakes aren't quite as high!

Can't see this as a gull-billed tern - and it should be a bit smaller than the lesser crested tern, not bigger. I'd easier see it being some odd plumage/bill-colour of lesser crested.

Yes I think you must be right, and I realized that the bill is completely the wrong shape for a gull-billed tern!

Not posted.

Oops silly me! Will be sure to attach them this time! Those are the photos of the tern on a buoy.

 

[AFM]

your "gull-billed" looks like sandwich to me. Its back is slightly lighter in colour than the lesser-crested next to it [to my eyes] and its bill is the right shape. Flight feathers are perhaps darker than expected but not impossibly so.

This crossed my mind too, because it really did seem a bit bigger than the lesser crested that was there, and I think sandwich terns are supposed to be slightly bigger than lesser crested? I've added the other photos I have of this bird, including two with the lesser crested walking right next to it for size comparison

 

[Butty]

the photos of the tern on a buoy

Yes, bridled tern(s). See the contrast between the upperparts and hindneck/crown.
Sandwich tern for your other one seems v possible, as Fern says.

 

[smiths]

Pic 2, just below right of centre, head down - bridled tern?

The head pattern, which is essentially the same as that of the other terns around it as confirmed by the additional photos in post #5 (encircled red), rules out Bridled/Sooty, as does the prominent white fringe on at least one tertial. See also the suggestion of pale grey upper mantle in these photos.
The most logical option is that this is a White-cheeked (or Common?) Tern with soiled or somehow unusually dark wing coverts (photographic effect perhaps?).