[Dave Kennedy]

I would appreciate an ID on the terns arrowed in the three photographs. They show two individuals on the same rock. Each had a full black cap, very white cheeks, red legs, and a bi-coloured bill which was half red (at the base) and half black (at the tip). The pictures are not wonderful, but the best I could do under the circumstances.

Photographed at Paternoster, Western Cape, on 23rd March 2011.

Thank you,
Dave

[birdboybowley]

See here Dave
http://www.birdforum.net/showthread.php?t=196129

[Dave Kennedy]

Originally Posted by birdboybowley

See here Dave
http://www.birdforum.net/showthread.php?t=196129

You're missing the point - neither you nor anyone else commented on the three terns arrowed in these pictures, although I specifically asked about them in the original posts. So I'm still trying to find out what they are.
Dave

[birdboybowley]

I did say they looked like Commons - and still stand by that!

[Dave Kennedy]

Originally Posted by birdboybowley

I did say they looked like Commons - and still stand by that!

I agree that the ones in those pictures are common - no quibble there - but I'm talking a) about the smallish tern on the left with the speckled forehead, which feature Sasol claims is shown by Antarctic tern, and

b) about the terns arrowed in "SA Terns II" with full black caps, red legs, white cheeks, and bi-coloured bills. So far nobody has come up with a comment on these.
best wishes,
Dave

[njlarsen]

Hi Dave,
I think Ads is saying that he thinks that the red-billed terns are within the variation of common tern. I would for myself say that the speckled forehead probably is a sign of moult (to or from breeding plumage) that is not limited to any single species, even if one species is more commonly seen at that stage in SA waters than the other. I think I have read somewhere that Arctic tern wears red on the bill for a shorter period than common, and has a shorter bill. I know for a fact that they have very short legs, and I believe that outside of breeding areas, they are more pelagic than common t.

Niels

[Trevor Hardaker]

Agree with the others who have all suggested that the bird in question is a Common Tern. Some of the birds here in South Africa will be starting to moult into summer (breeding) plumage now which would seem to be what you have with this bird here.

Unfortunately, because we so seldom get to see them in summer plumage here in South Africa, most of our local field guides don't really deal with this plumage at all or very poorly if they do and it often causes confusion amongst local birders.

Also, in South Africa, Arctic Tern are, as Niels has indicated, mostly pelagic - one hardly ever encounters them on shore. In several decades of looking at terns roosts in the Cape, I have only ever seen Arctic Tern in the roosts on a handful of occassions. However, on the pelagic trips that I do in our summer, I encounter them on virtually every single trip.

As to Antarctic Tern, they are a winter visitor to our area. They arrive in the Eastern Cape around mid to late April and arrive in the Western Cape several weeks into May, so it would be too early to be expecting them on the west coast now.

[Jane Turner]

I'm seeing Common Terns arrowed

[Dave Kennedy]

Right, folks, thanks to all the contributors - it's all starting to make a bit of sense now. I've never experienced common terns in their breeding plumage. I wonder why that pair should be so advanced into their summer plumage, while thousands of their conspecifics are not? What are the triggers that initiate the plumage change?

Thanks once again,
Dave

[Dave Kennedy]

Originally Posted by Trevor Hardaker

As to Antarctic Tern, they are a winter visitor to our area. They arrive in the Eastern Cape around mid to late April and arrive in the Western Cape several weeks into May, so it would be too early to be expecting them on the west coast now.

Thanks for your contribution, Trevor.
It seems clear that information in field guides may be less than precise. We had SASOL with us as we were watching the terns. Re Antarctic Tern, Sasol states "In non-breeding plumage it is white to pale grey below (depending on race) with a conspicuously grizzled crown". When referring to status it comments "Fairly common winter visitor to Cape coastal waters, small numbers in summer on west coast". This is what led me to suggest that the tern with the grizzled crown might be an Antarctic tern.

If one does not live on the coast terns are hard to identify. They have variable plumage, are often skittish, take wing in their thousands, wheel around and settle somewhere further along the beach, forcing one to start all over again to scan the gang for potentially interesting individuals. It can all be quite frustrating.

Once again, thank you for your reasoned input.
Best wishes,
Dave

[Trevor Hardaker]

Dave, yes I think that comment about small numbers on the west coast in summer is perhaps a little misleading unless, of course, by small numbers they are mean literally a handful of birds...

Yes, one might be lucky and find 5 or 10 birds on the entire west coast in our summer, but these would almost certainly be first year birds, the plumage of which is not dealt with at all in any of the local field guides, so is just bound to cause even more confusion. In all my years of working through tern roosts on the west coast, I have personally never come across an adult Antarctic Tern here in our summer. Given that they would be in breeding plumage then, they would also not be difficult to miss, so I'm pretty certain that there are no adults here in our summer.

Yes, terns can be tricky work, particularly for those who are not often exposed to them. Add to that the fact that, on the west coast anyway in our winter, the tern roosts hold at least 2 different races (possibly more) of Antarctic Tern here which look noticeably different, it is certainly a recipe for confusion...

[birdboybowley]

Terns eh....getting as bad as sorting through gulls!