Monday, September 13, 2010

Mystery tern Ogden






Any thoughts on this one. The bird showed an all black bill and black feet. Some people suspect it to be a first winter Roseate Tern although the tertials look more like Arctic ? The trailing edge of the secondaries showed a very noteable white line and there was a noteable white tertial step. The primaries also showed a white edge and faint scalloped effect could just be seen on the mantle. The conditions were very bad so poor quallity to pictures, Dave might have some better ones.



7 comments:

AndyC said...

The 1st summer Artic in Collins looks bang on.

Andrew Huyton said...

Totally agree with Andy, Collins shows 1st summer spot on. Still good find and lesson in id, was the other def a common? and not another arctic, any photo's?

David Sutcliffe said...

Despite several views of the bird in flight there was no indication of any black line on the trailing wing ! I would have expected to see this unless they lose it in winter plumage (?)

Dave Barker said...

Nick – I Have looked a bit closer and here are my preliminary thoughts for post on blog.

Sheesh – hard!

1 if the bird did call like a sandwich tern (cum spot redshank) then that’s supposed to be diagnostic of Roseate
2 Personally, I’d be very loathe to rule out Roseate on perched photos, tho that doesn’t mean it is one and it doesn’t look lumpen Rosy jizzy – but then not arctic dumpy , small billed cute either. To me, the open wing tip pattern needs to be seen because I believe juv wing tip pattern is same as on adults. And, assuming wings are retained until in winter quarters, that would clinch it as on underwing primaries it would have either a thin dark trail edge along all but innermost few prims = Arctic, or the trailing edge of primaries would look basically white as Roseate lacks the black trailing rim – except a bit at very outer prims. Whether this can be worked out by studying closed wing I’m not sure. In some pics it looks as if the upper border is almost a solid white line along top of wing – does that hint at a rosey-type pale tip if wing were open??
3 Legs and bill colour could be either species in 1st w
4 the exact shape and distribution of the black behind eye is crucial but, frankly, I don’t understand the more advanced lit on this – the pic looks like pics of Arctic in consequence!
5 However, I think the normal depictions of imm roseates in books show juveniles – ie the ones patterned like mini-swichs. First winters are much plainer backed, have white forehead (by now anyway) and closer to arctic
6 flight mode –like I said, to me they bat along like a swich or little tern – rapid wings and front-heavy but that’s at sea!
7 not sure if rump is grey or white on rosey (I thought latter – might be wrong)
8 I’m not sure it’s a ‘portlandica’ – ie 1st summer – wouldn’t the prims be worn v dark by now and tertials tatty, plumage have mix of diff age feathers etc??? (duno)

If I get chance to look at deeper lit I will. Somewhere I have Kaufmann’s US advanced Bird ID which I used to find better on these terms than owt in UK – tho Collin’s should be best as Killian M is a renowned rosey ID expert.


Very instructional bird for us inlanders - whatever it is!

Mick Cunningham

(Comment received from Mick overnight and posted at his request.... Dave Barker)

Dave Barker said...

Nick – I Have looked a bit closer and here are my preliminary thoughts for post on blog.

Sheesh – hard!

1 if the bird did call like a sandwich tern (cum spot redshank) then that’s supposed to be diagnostic of Roseate
2 Personally, I’d be very loathe to rule out Roseate on perched photos, tho that doesn’t mean it is one and it doesn’t look lumpen Rosy jizzy – but then not arctic dumpy , small billed cute either. To me, the open wing tip pattern needs to be seen because I believe juv wing tip pattern is same as on adults. And, assuming wings are retained until in winter quarters, that would clinch it as on underwing primaries it would have either a thin dark trail edge along all but innermost few prims = Arctic, or the trailing edge of primaries would look basically white as Roseate lacks the black trailing rim – except a bit at very outer prims. Whether this can be worked out by studying closed wing I’m not sure. In some pics it looks as if the upper border is almost a solid white line along top of wing – does that hint at a rosey-type pale tip if wing were open??
3 Legs and bill colour could be either species in 1st w
4 the exact shape and distribution of the black behind eye is crucial but, frankly, I don’t understand the more advanced lit on this – the pic looks like pics of Arctic in consequence!
5 However, I think the normal depictions of imm roseates in books show juveniles – ie the ones patterned like mini-swichs. First winters are much plainer backed, have white forehead (by now anyway) and closer to arctic
6 flight mode –like I said, to me they bat along like a swich or little tern – rapid wings and front-heavy but that’s at sea!
7 not sure if rump is grey or white on rosey (I thought latter – might be wrong)
8 I’m not sure it’s a ‘portlandica’ – ie 1st summer – wouldn’t the prims be worn v dark by now and tertials tatty, plumage have mix of diff age feathers etc??? (duno)

If I get chance to look at deeper lit I will. Somewhere I have Kaufmann’s US advanced Bird ID which I used to find better on these terms than owt in UK – tho Collin’s should be best as Killian M is a renowned rosey ID expert.


Very instructional bird for us inlanders - whatever it is!

Mick Cunningham

(Comment received from Mick overnight and posted at his request.... Dave Barker)

Dave Barker said...

Nick – I Have looked a bit closer and here are my preliminary thoughts for post on blog.

Sheesh – hard!

1 if the bird did call like a sandwich tern (cum spot redshank) then that’s supposed to be diagnostic of Roseate
2 Personally, I’d be very loathe to rule out Roseate on perched photos, tho that doesn’t mean it is one and it doesn’t look lumpen Rosy jizzy – but then not arctic dumpy , small billed cute either. To me, the open wing tip pattern needs to be seen because I believe juv wing tip pattern is same as on adults. And, assuming wings are retained until in winter quarters, that would clinch it as on underwing primaries it would have either a thin dark trail edge along all but innermost few prims = Arctic, or the trailing edge of primaries would look basically white as Roseate lacks the black trailing rim – except a bit at very outer prims. Whether this can be worked out by studying closed wing I’m not sure. In some pics it looks as if the upper border is almost a solid white line along top of wing – does that hint at a rosey-type pale tip if wing were open??
3 Legs and bill colour could be either species in 1st w
4 the exact shape and distribution of the black behind eye is crucial but, frankly, I don’t understand the more advanced lit on this – the pic looks like pics of Arctic in consequence!
5 However, I think the normal depictions of imm roseates in books show juveniles – ie the ones patterned like mini-swichs. First winters are much plainer backed, have white forehead (by now anyway) and closer to arctic
6 flight mode –like I said, to me they bat along like a swich or little tern – rapid wings and front-heavy but that’s at sea!
7 not sure if rump is grey or white on rosey (I thought latter – might be wrong)
8 I’m not sure it’s a ‘portlandica’ – ie 1st summer – wouldn’t the prims be worn v dark by now and tertials tatty, plumage have mix of diff age feathers etc??? (duno)

If I get chance to look at deeper lit I will. Somewhere I have Kaufmann’s US advanced Bird ID which I used to find better on these terms than owt in UK – tho Collin’s should be best as Killian M is a renowned rosey ID expert.


Very instructional bird for us inlanders - whatever it is!

Mick Cunningham

(Comment received from Mick overnight and posted at his request.... Dave Barker)

Dave Barker said...

Sorry for the multiple comment! it did'nt seem to want to work for me either. Dave