Arctic Tern, Ashley Rakahuri Estuary

[benackerley]

This looks like its the same bird as the one coming into breeding plumage. This was on the 9th of FEB

[Oscar Thomas]

When we keep comparing individuals to other individuals it gets messy and calls into question the original identifications. Little plumage details also do not confirm whether individuals are the same especially with weeks/months between sightings. It would be better to go back to the descriptions and diagnostic features. Per Australian Bird Guide one of my favourites, my notes are as follows:

Adam’s new Ashley Arctic:
This is a round, muscly bird that looks built to fly around the planet. Head small and rounded, legs very short, belly almost touching ground. I haven’t heard of Arctics getting a red bill before their black cap but structurally it is one.

Long-staying red-billed common:
This bird is much flatter in head and body structure, as such it looks almost stretched thin compared to an Arctic apart from proportionally shorter wings. In non-breeding plumage the white cap never extended as far back as expected in Arctic. Lastly it would be unusual for an Arctic tern to stick with a WFT flock for certainly two if not four months, if this is the same bird Peter observed originally in Dec.

[Adam C]

Cheers Oscar.
Peters Antarctic Tern was seen after a decent Southerly blow and then disappeared next day. Still a mile from home but makes sense. I think it's highly unlikely an Antarctic Tern would stay this far North for any length of time. I'm sure every grain in its compass would pull it South very quickly. April is a key time for Arctic Terns to be heading back up along our coast on migration so in terms of share probability I'd swing Arctic too.

Must admit when I first saw the bird I was blown away by the RED and thought Antarctic but will we ever really know lol.

Also by now an Antarctic Tern should be in full non breeding mode and that bill (if I'm correct) should be dark red to pinkish/patchy to almost black not bright red. See pics below

[tim]

Hi Oscar,
I don't agree with your comments we base all our id features on little plumage details to confirm the identity of the subject and as you said this would mean that previous id's are incorrect as the bird matches the id features.

If you look at this link and Ian Southey has some pictures of this time of year showing birds in the exact same plumage details confirming this is an Antarctic tern viewtopic.php?t=5790

Stewart Island 2 19-4-070075b.jpg (272.23 KiB) Viewed 471 times

Normally for an Arctic tern they are normally just stop over bird on migration both ways but they have been known to spend a bit of time in one area, I remember the Hawkes Bay bird stayed around for 3-4months and you could consistently re-find it its locations it was hanging around so it's not out of the normal for this species.
We also all know of birds being lost and been hanging around an area for some time.

I still think that this bird 1 is Antarctic Tern,
It matches all the photos that I have seen and from many of them they seem to retain most of the blood red bill in non breeding plumage compared to an arctic that would have black bill with tiny amount of red at the base of the bill in non breeding, this Antarctic is in non breeding at the moment.
There is many reasons why its belly might be closer to the ground as wind may push it down or it might be well fed.

FB_IMG_1712209643430.jpg (27.02 KiB) Viewed 471 times

Bird 2 is Arctic tern
This bird matches Arctic's that I have seen and looks good for going into breeding plumage now as it is around 1-2 months away from full breeding plumage.

FB_IMG_1712209648797.jpg (38.62 KiB) Viewed 471 times

Bird 3 is Common tern

FB_IMG_1711085458799.jpg (39.66 KiB) Viewed 471 times

[FraserGurney]

Hi Tim,

While I agree the first bird could be an Antarctic, I'm still leaning towards Arctic as it ticks all the boxes structurally.

The second bird is the common tern that has been hanging around the Ashley for a while now. The head is too flat for Arctic, the legs and bill too long, and the plumage matches common. Local birders have been watching it progress for a while now.

This all demonstrates how tricky terns can be and it's a great conversation to have.

[Steve Wood]

Some great looking Terns on view at the mo backed up with some stunning pics, however still some confusion for most and rightly so.

Bird 1) Is clearly an Arctic or Antarctic for me - I think the key thing that is missing which would have been helpful is some indication of size.Considering there is a multiple selection of Tern species nearby this should have been fairly easy to get an indication.
Doesn’t seem to have been mentioned ?
According to Aussie field guide when comparing wt. Antarctic tern is generally heavier than Arctic , Antarctic = 115-190g, Arctic 80 -120g and even heavier than White- fronted 105-160g Always exceptions with some overlap but potentially a good steer.
No expert on moult but, is the bird coming in to breeding plumage (Arctic) or going out Antarctic ?

Bird 2) Is ssp. Sterna hirundo (see below) not an option, as opposed to ssp. Longipenus ?
I can’t see bird (2) being an Arctic,head shape and general shape just doesn’t look right and appears too big in every dimension for me. Again no indication of size which would have been helpful and leg length is hard to judge accurately due to posture/ mood of the bird appears to be different.

IMG_1327.jpeg (214.87 KiB) Viewed 341 times

‪‬

[Adam C]

Steve my thoughts exactly re S. hirundo which makes it a special bird. The moult question would solve once and for all the first bird. Re size I have to admit that I was so dam excited with both of these birds turning up simultaneously after waiting 3 hours I didn't really pay too close attention BUT I didn't notice it being any smaller than surrounding birds but thats not to say that it wasn't as I was very zoned in' shall we say Personally I'm now leaning towards Antarctic re the full red bill and completely 'non breeding' cap however we could argue the red bill on an Antarctic should be darker by now too so again..... If anybody can answer the moult question this gives us hopefully enough evidence to submit a UBR for the bird rather than a question mark!

[benackerley]

I took some photos of bird 2 a few days before Adam saw it. Only phone photos on me atm but it does look smaller than the common terns

[Adam C]

Probably no help but 2 more shots here. At a glance scapulars appear worn but most other feathers appear fresh if any help? Would just love to ad this to ebird and submit a UBR for this special visitor.

[tim]

Hi Adam,
Yea I would submit a URB for bird one to be Antarctic.
If bird two is S hirundo this would be a first for NZ wouldn't it? its leg colour and primary's match hirundo plus I have seen full breeding plumage longipennis and its quite different.
It will be interesting if it stays a bit longer and completes its moult into full breeding plumage and confirms the id.

Also regarding the flat head I have photos of commons with round head and its all to do with if they raise there neck etc, if the tern is sitting in a relaxed pose then the head might be flat.