Antarctic Tern

  • Jeff Curnick
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8 years 4 months ago #11746 by Jeff Curnick
Jeff Curnick created the topic: Antarctic Tern
Hi all,

Stopped off at the Nahoon Reef (East London) earlier today and picked up an Antarctic Tern in full breeding plumage amongst a small group of Swift and Common Terns. A first for me in the EL area.

Two pics by George Branford:







Enjoy,

Jeff

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  • Camby
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8 years 4 months ago #11753 by Camby
Camby replied the topic: Re: Antarctic Tern
Now THAT is nice!!!
I visited a colony at Mauritzbaai a few weeks ago and none were in breeding plumage :( Not nearly as pretty as this guy

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  • NickyO
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8 years 4 months ago #11776 by NickyO
NickyO replied the topic: Re: Antarctic Tern
Very nice!! <!-- s:yes: --><img src="{SMILIES_PATH}/yes.gif" alt=":yes:" title="Yes" /><!-- s:yes: -->

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  • outbirdme
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8 years 4 months ago #11960 by outbirdme
outbirdme replied the topic: Re: Antarctic Tern
Would Antarctic Tern be in breeding plumage at this time?

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8 years 4 months ago #11961 by NickyO
NickyO replied the topic: Re: Antarctic Tern
Some sources say the breeding period is from November to December, others have recorded egg laying from as early as October through to as late as March... There is also a question of which sub species we are talking about. According to some texts some of these sub species are migratory and others are not, so this and the availability of food will affect their breeding behaviour.

Never a simple answer to anything... <!-- s:spin: --><img src="{SMILIES_PATH}/spin.gif" alt=":spin:" title="Spinning" /><!-- s:spin: -->

I guess only long term research will answer the question properly as to whether this bird should be in breeding plumage right now... <!-- s:bouncy: --><img src="{SMILIES_PATH}/bouncy.gif" alt=":bouncy:" title="Enthusiastic" /><!-- s:bouncy: -->

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8 years 4 months ago #11983 by outbirdme
outbirdme replied the topic: Re: Antarctic Tern
It would be very unusual given their breeding locations are in the dead of winter at this time and that the earliest expected breeding is not for a few months.
Arctic Tern would be in full breeding now and the Antarctic would be expected not to be. Raising an interesting point, given that many birders use this as the means by which to seperate the species. Excellent that you looked at other features.

It also brings me to another question. As some adult Terns do not breed in consecutive years, do they still moult into breeding plumage during the summer months when they are not breeding. If they do, a long distance migrant like Arctic Tern might land on our shores during the Boreal Summer.

By virtue of the fact that the bird is on our shores, it has undergone a migration but as far as is known, two subspecies have been recorded on Southern African shores - [i:naup3qdh]vittata[/i:naup3qdh] and [i:naup3qdh]sanctipauli[/i:naup3qdh].

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8 years 4 months ago #11984 by NickyO
NickyO replied the topic: Re: Antarctic Tern
Would you know how to tell the difference between [i:13nw44bt]vittata [/i:13nw44bt]and [i:13nw44bt]sanctipauli[/i:13nw44bt]?

On the question of plumage I would guess that a migratory bird would be a lot more opportunistic in it's feeding and therefore breeding behaviour?

Also how much is known about these birds... would they migrate further north during the southern winter and breed on our shores? Maybe one of the subspecies actually does this and this is what we are seeing?

In a lot of the articles they do point out that not a lot is known about this species.

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  • nkgray
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8 years 4 months ago #11985 by nkgray
nkgray replied the topic: Re: Antarctic Tern
Sitting here in Guinea with Sinclair & Ryan and Borrow & Demey, so absolutely nothing to get tern info.

Below a composite of George's Antarctic Tern and my Arctic Tern (breeding colony at Minsmere, Suffolk, England less than a month ago). Can someone explain why Jeff's Antarctic Tern that should not really be in breeding plumage at this time of year is not a vagrant Arctic Tern in breeding plumage in the least likely time of year to see one in SA according to the seasonality table on the Zest for Birds site???? Chances of either seem very small. So which is it?



Neil

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8 years 4 months ago #11986 by outbirdme
outbirdme replied the topic: Re: Antarctic Tern
I attempted to find out the differences between the two subspecies but in the short time I only managed to confirm that there are perhaps 4 ssp recognised as occuring here, and needless to say, it depends on the listing authority. Some of you won't even recognise [i:3107dgpd]sanctipauli[/i:3107dgpd]. Have a look at table 3 in this paper - http://docs.google.com/gview?a=v&q=cach ... tern&hl=en -for a better understanding of which subspecies are usually where.

As I mentioned earlier, if we know that Arctic Tern individuals do not breed every year, and that they still moult into breeding plumage regardless, that would be a condition under which we might see them here at this time of year, in breeding plumage - since they are not tied to the breeding grounds.
Or perhaps it was a failed/early breeder that began it's southward migration early.

As far as physical identification characteristics are concerned, the leg and tail length differences are important - maybe an observer with experience with thge two species could comment. Secondly, the photo isn't from the correct angle to determine the colour at the wing tips - they would show darker tips in Arctic Tern. This actually seems to be present in the image but it could be the lighting.

I have seen breeding Antarctic Terns in the Antarctic, and breeding Arctic in the Northern Hemisphere but have never had to practice seperating both in breeding plumage.

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8 years 4 months ago #11989 by NickyO
NickyO replied the topic: Re: Antarctic Tern
In texts I have read they talk about bill colour in the breeding birds with Antarctic having a "heavier corel red, darker bill"... it could just be a trick of the light but comparing Neil's two photo's the one of the left does appear to be darker?

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