[Silverwolf]

Picked out these two in a flock of Crested Terns on Sunday. I'm guessing from a limited knowledge they are both Common (but they are definately not common around here, mind you).

http://www.birdforum.net/gallery/sho...0/limit/recent
http://www.birdforum.net/gallery/sho...1/limit/recent

[halftwo]

Look like Arctic to me.

[Silverwolf]

Arctic would be a good one, as my guide lists them as a rare migrant around here.

Anyone else?

[Mat & Cathy]

Common is more likely where you are. Field-guides will give you some pointers on ID between Arctic and Common. I think one of the features of Common is a dark edge to the tail - which I can "almost" see in your flight shot.

Cheers
Mat

[Silverwolf]

My guide is complicating the matters further. For one it says the Common occurs in two subspecies, one being the typical orange-black billed one from Europe and an all-dark billed one, the latter of which the first bird clearly has.

But it shows that the Arctic has a fine black edge underneath, and the Common has a smudgy grey patch. In this picture here of the adult it clearly shows a fine black edge.

http://www.birdforum.net/gallery/sho...0/limit/recent

It seems to me it has features of both species, unless Arctic Terns sometimes have a dark bill (in breeding plumage that is).

@Mat & Cathy, It also says that a dark edge to the tail is a feature of the first-winter Common.
The juvenile/immature can wait for now....

[njlarsen]

Your second bird is clearly not a bird in breeding plumage, so for that one you will have to look at younger birds and/or winter plumage. I am not sure about timing in your area, not sure about when the adults have finished changing into adult plumage and bill color.

Niels

[Silverwolf]

Originally Posted by njlarsen

Your second bird is clearly not a bird in breeding plumage, so for that one you will have to look at younger birds and/or winter plumage. I am not sure about timing in your area, not sure about when the adults have finished changing into adult plumage and bill color.

Niels

The terns achieve their breeding plumage from the end of September, which is around now. The second bird I had presumed was an immature (or another species entirely, as I hear some species are in breeding plumage when others are in non-breeding). This is confirmed by the fact that the black-billed Common Tern of this area is in breeding plumage during the Australian "summer" whereas the Arctic and European Common are in breeding during the Australian "winter". The non-breeding Arctic definately does not match the second bird.

Until further notice I will probably be leaving them as Common subsp. longipennis.

[J. Moore]

The second bird cannot be a Common Tern because the legs are too short. I believe it is an Arctic Tern in very worn non-breeding plumage. I've found a number of photos that seem to be a good match: http://birdfreak.com/digiscoping-arctic-tern/

Best,
Jim

[snowcap]

The second bird is an Arctic Tern, as J.Moore says, the legs are too short for Common, also the shorter bill and larger head/bigger eye appearance is good for Arctic too.Also the underside of the far primaries is too white for Common.

[Silverwolf]

Thanks for the help. This is not a bad bird to have on my list. Will in future make sure to check every tern (there was actually 3 Sterna terns there, and the 3rd one looked exactly like the 2nd so I dismissed it).

[Jeff Davies]

Hello Silverwolf,

I am also a local from Melbourne and here we are discussing a local observation via the UK.
I believe both of your birds are Arctic, the bird in flight included which has same age primaries without a darker outer wedge of feathers, a very narrow white margine above the gape and if you look hard it actually has a couple of white feathers in the central crown interupting the profile. The dark bill doesn't really concern me in fact it looks a bit reddish in gape.
I am wondering if the bird on the deck may be a second year, very advanced for an adult in head, scapulars and tertials and possibly too trashed in the wing for a juv.
Would love to speak with you on the local phone about these birds, have sent personal message with phone number.

Cheers Jeff Davies.

[njlarsen]

Jeff, welcome to birdforum!

Niels

[Benjoman]

Have nothing to add to the debate over your Commic Tern, Silverwolf, in terms of an ID, however note that there are a number of sightings of both Common and Arctic (and White-Fronted for that matter) over the last week or so at Ricketts Point & Mordialloc.

Check out Birdline Victoria for latest details:
http://www.eremaea.com/BirdlineRecen...spx?Birdline=1

[John_WA]

Originally Posted by Benjoman

Have nothing to add to the debate over your Commic Tern, Silverwolf, in terms of an ID, however note that there are a number of sightings of both Common and Arctic (and White-Fronted for that matter) over the last week or so at Ricketts Point & Mordialloc.

Check out Birdline Victoria for latest details:
http://www.eremaea.com/BirdlineRecen...spx?Birdline=1

I think quite a few birders have headed down there after news of this sighting was posted on the Birding-Aus mailing list