Arctic Tern, Ashley Rakahuri Estuary

[David Melville]

HANZAB record two records of European-banded hirundo in Australia.

[Adam C]

Sav agree. Waiting for someone to chime in with the significance of it, or if western pops of Longipennis have red bills? Thought maybe I'd missed something...

[sav]

As it happens, I saw a Common Tern with a red bill in Hawaii last September. It seemed to me that an Eastern origin ought to be more likely than a Western one given the distances and prevailing winds. But apparently not.

It's a flippin' long way from Hawaii to here though!

cheers

[Adam C]

Ok attached below is the only image I have of the Arctic/Antarctic tern with a WFT in the frame. It looks biggish here but these are shot at 3000mm equiv and background birds at extreme zoom do appear larger.

Also re the Red-Billed Common it may just be Longipennis having re-read my copy of Terns of Europe and North America.

Regarding race 'longipennis' "a broad intergrade zone occurs in Siberia/central Asia, where birds with red basal 50% of bill predominate (red generally darker than on european birds). The percentage of Black-billed birds increases progressively eastwards. In Kamchatka and in east Siberia the bill is black, but a few percent have red bill base.

Reading this it seems the line between Hirundo and Longipennis is pretty blurred!

[Steve Wood]

Antarctic tern photographed on Kangroo Island (OZ) Sept.
Bill colour as stated in the aussie field guide -

Antarctic - Vivid red with variable black tip to base and tip (non breeding Ad.)
Arctic - Dark red (breeding Ad, April to Aug)
Looking at this pic I would have said that it is the other way around when defining the colour red.

IMG_1336.jpeg (337.37 KiB) Viewed 288 times

[Adam C]

Ok I know this has dragged on for a bit but for me personally this key piece of information combined with the structure and all other factors combined makes this an Arctic Tern as most of you are backing.

There is a great link here: https://faansiepeacock.com/identifying-antarctic-terns/

This is well worth reading right through but key is the moult cycle graphs which I have included screenshots of below. Yes this is a different subspecies of Antarctic tern but moult cycle should be identical. The only one that really matters here is the blue line for Primary moult which clearly shows Arctic terns having just finished their primary moult so they will be sporting fresh new primaries which this bird has and is still growing the last outer primary as picked up by David Melville.

Antarctic terns by now are close to starting primary moult meaning they would be carrying old, dark and worn looking primaries similar to our White-Fronted Terns right now (white-fronted terns obviously not as dark) This whole bird looks way too clean and fresh for a tired, post breeding bird. Also if we look at the breeding Arctic tern on NZ birds online photographed in Plimmerton in May only 4 weeks on it has a complete red bill. Only this birds cap needs to catch up and this can happen pretty rapidly. Also second year birds never have a full breeding cap so again could be a possibility here?

Anyway Arctic for me. Thanks for all the help and discussion on here!

[Oscar Thomas]

Nicely done Adam, that looks pretty conclusive!

[Steve Wood]

Yes indeed well summarised. Arctic it is then.

[Adam C]

Red-Billed Common present today again at 4pm Almost full breeding cap. Very happy Jack was with me to see it too!

[tim]

any other photos? that tail is long and now that common I was saying is looking very arctic like.