Arctic Tern, Ashley Rakahuri Estuary

[benackerley]

DSCF0349-Enhanced-NR.jpg (175.37 KiB) Viewed 471 times

Heres a flight shot I got on the first of April.

[Adam C]

Hi Tim. Ben A. Has a photo of the underwing of this bird from a few weeks back showing translucent hand only and diffuse dark back edge.

[Adam C]

Heres another shot and one of Jack after we'd belly crawled for about 100m. Bird lifted and came and settled about 10m in front of him at one point! Super chilly on the wet sand but worth it...even if we come down with colds this weekend! We belly crawled back and birds were very relaxed today. Unfortunately this idiot had driven across the estuary and was stuck the entire time we were there. Not much we could do to help. Tide was not around his wheels at the start but well up when we left. Rescue vehicle seemed to be coming in as we pulled back up kings ave but didn't see the outcome.

[Ian Southey]

I've been away and missed all the fun but that bird looks very much like a strong candidate for the western subspecies of Common Tern to me. It looks so fat that it may not stay long but could you locals please try to go through the whole list of differences, not just the bill colour, and try to see and describe or photograph them. This may prove to difficult to assess because these terns are both similar and variable and as a first record the required standard will be quite high.

Some of the differences may be average differences and not necessarily obvious on all individuals so look for them all. The more characters there are that align this bird with one or the other subspecies the more confident we can be of the identification. One of Adam's excerpts has a list of things to look for (although I am not sure what they mean by a cheek stripe on Common Terns). Some may be easier to see than others but even subtle differences in bill length can sometimes be obvious and may change the head shape. For the photographers be careful with the lighting - in nice sun it is quite easty to burn out subtle differences in greys and whites so pictures on overcast days might show more and also try underexposures, maybe by 2-3 stops. Photoshop can't find things that aren't there and photos aren't always better than careful observations. Keep an eye out for the black billed bird, even if it doesn't go into breeding plumage it may still allow a useful comparison of jizz especially wing and bill length.

Good luck

Ian

[Adam C]

Hi Ian.

Not sure if this helps but a great full frame shot by Jack yesterday when the bird actually lifted and landed in front of him. I have a great wee video of the bird too which I'll try and create a link to. It was also bloody cold yesterday so the bird is pretty puffed up

By cheek stripe they mean the area between the grey flush and the black cap Im assuming. Not quite created on this bird yet?

[Adam C]

Have added the video to New Zealand Birders facebook page Ian if any help.

[sjacques]

Some great discussion here. Doing a bit of reading around I find a reference on the Wikipedia page for common tern to a ringing recovery on Rakiura/Stewart Island of a juvenile banded at a Swedish nest. Presumably this individual would have been S.h.hirundo. Reference cited is Newton (2010), anyone else aware of this record?

Cheers,
Sean

[David Melville]

NZBirdsOnilne gives this as a record for ARCTIC Tern, not Common Tern.

[Byrd]

Some great discussion here. Doing a bit of reading around I find a reference on the Wikipedia page for common tern to a ringing recovery on Rakiura/Stewart Island of a juvenile banded at a Swedish nest. Presumably this individual would have been S.h.hirundo. Reference cited is Newton (2010), anyone else aware of this record?

Cheers,
Sean

Newton seems to have been the one to be confused (having it as a Common Tern) which has then been repeated by other sources.

The bird was recovered in 2003 and was an Arctic Tern, and the specimen was deposited at Te Papa. Report is in Southern Bird 2004 (pdf at this link):
https://www.birdsnz.org.nz/wp-content/u ... un2004.pdf

[Michael Szabo]

Here's a photo I took of a Common Tern in breeding plumage at Plimmerton on 21 March 2022 for comparison. The bill was dark with a dull red lower mandible. At the time Alan Tennyson noted that according to HANZAB, birds with this feature originate from central Siberia and represent the western population of the longipennis subspecies (or even a separate subspecies).