Ambiguous tern (1 Viewer)

[Michał Jaro]

I know it's probably about a common tern - but its appearance is so strange to me that I can't resist posting it on the forum.
Dark (blackish) 3 primaries, no dark stripe under the wing at the tips of the primaries, red at most half of the beak, overall light appearance, wings appear short. So I want to make sure it's definitely not Roseate tern.
I'm sorry for the terrible photos, I hope you can see what's most important.
Poland, Podhale, july

 

[Southern Frogmouth]

Hi Michal,

It is a striking bird and I think it is a Common Tern. I have seen one or two 1st summer (2CY) and 2nd summer (3CY) birds at my local patch and they can show quite a striking wing pattern as this bird does and often arrive later than breeding adults. Also immature birds can have completely black bills in summer or more extensively black bills than an adult Common Tern - although adult Commons early in Spring can have just a small amount of red at the base of the bill. Did this bird have a small white forehead as well? Some 2nd summers do have this and most/all 1st summers have an extensive white forehead. I think I can see it in some photos but can't be certain.

On balance I would say 2nd summer Common Tern as it doesn't look clean, but is some way towards adult plumage. The outer primaries appear as a dark wedge above and below on the wings of Roseate whereas this bird has a dark outer edge on the outermost underwing feather and a short trailing edge on three or four of the outermost primaries and probably has quite old feathers in the primaries which suggests immature.

1st summer and 2nd summer Common Terns are unusual in Europe but not unheard of and can present a challenge to put a name to.

 

[Michał Jaro]

Thank you very much for your help. I didn't realize Common terns could look like this. And I didn't know that their aging is so complicated. answering the question - yes, this bird has a slightly lightened/whitish forehead.
I will add that I have not seen a similar common tern before, although I see several dozen every year.

 

[lou salomon]

I'd expect visible pale fringes to inner (new) primaries at least in pics 7 and 8 (9099, 9100) in a Roseate. Don't know what's wrong with Common Tern having a black wedge formed by old outer primaries?

 

[Michał Jaro]

Don't know what's wrong with Common Tern having a black wedge formed by old outer primaries?

It's hard for me to answer this question, I can only say that this one is different from all the ones I've seen so far (due to the contrast of the this black wedge on few outer primaris) and I don't see any stripe on the edges of the primaries (in fact seems to be too short).
I know from Collins that young 1-year-old birds can have such contrasting outer primaries - but they look different. In fact, I haven't found any photos showing an adult Common tern similar to mine.

 

[njlarsen]

I'd expect visible pale fringes to inner (new) primaries at least in pics 7 and 8 (9099, 9100) in a Roseate. Don't know what's wrong with Common Tern having a black wedge formed by old outer primaries?

Wouldn't a common usually have a wedge consisting of about 6 dark feathers in mid summer, while roseate typically shows the three that this bird shows?

One thing to counter is that I feel some (but not all) of the photos indicates a dark outer edge on the outermost tail which I do not believe Roseate should show.
Niels

 

[Southern Frogmouth]

I don't think this bird is a usual bird to be honest. Another look at the photos suggests that the bird could be in wing moult, which is not usual in July in my experience. Apparently this can happen very early in failed breeders so it could actually be an adult carrying out an early moult into non-breeding plumage - I am not sure how quickly this would progress and how quickly the bill would start going black. Also terns can moult their primaries two or three times in a year so what is usual may not apply even if this bird is an adult.

 

[JTweedie]

I'm not going to lie: I thought for a moment that the Ambiguous Tern was a tern from the Pacific or something that I'd never heard of.

 

[Michał Jaro]

I'm not going to lie: I thought for a moment that the Ambiguous Tern was a tern from the Pacific or something that I'd never heard of.

Sterna dougallii Montagu, 1813

Global Biodiversity Information Facility. Free and Open Access to Biodiversity Data.

www.gbif.org

sometimes visits Europe

 

[Michał Jaro]

Another look at the photos suggests that the bird could be in wing moult, which is not usual in July in my experience.

I must apologize for my mistake - the date is June 19, not July as I wrote (perhaps it matters)

 

[Southern Frogmouth]

I must apologize for my mistake - the date is June 19, not July as I wrote (perhaps it matters)

I would think that makes the failed breeder option unlikely to be honest, but stranger things can happen.