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        Discussion Area 討論區 >> Bird Identification 鳥類辨識 >>  Brown Noddy at Po Toi?
        
(Message started by: geoff_welch on May 18^th, 2006, 6:49pm)

Title: Brown Noddy at Po Toi?
Post by geoff_welch on May 18^th, 2006, 6:49pm

I saw two birds yesterday at Po Toi which I believed were both Bulwer's Petrels.
However, my photos show they may be not be.
Here is the first bird

http://www.geocities.com/geoffwelch46/pa1.jpg http://www.geocities.com/geoffwelch46/pa2.jpg http://www.geocities.com/geoffwelch46/pa3.jpg
http://www.geocities.com/geoffwelch46/pa4.jpg http://www.geocities.com/geoffwelch46/pa5.jpg

Mike Kilburn believes this one is a Bulwer's based on seeing two of these photos through the camera today.
I would welcome other expert views.

The second bird was larger, in fact larger than the Bridled Terns it was with.
It seems to be missing some feathers between the primaries and secondaries,
also possibly in the tail (or it has a forked tail?).

http://www.geocities.com/geoffwelch46/pb1.jpg http://www.geocities.com/geoffwelch46/pb3.jpg
http://www.geocities.com/geoffwelch46/pb4.jpg
http://www.geocities.com/geoffwelch46/pb5.jpg

Any views on this bird would also be welcome.

Title: Re: Petrels at Po Toi
Post by HK_Twitcher on May 18^th, 2006, 7:55pm

Geoff

I agree with Mike After seeing these photos I think that it is a Bulwer's Petrel due to the long wings and tail all dark plumage.

According to the Collins Field Guide Bulwer's Petrel occasionally shows its rounded tail which it is doing in one of the photos..

Graham

Title: Re: Petrels at Po Toi
Post by miket on May 18^th, 2006, 8:09pm

Although some of the postures look a bit odd, with spread, cuckoo-like tails, and some odd body shapes, this must be due to the typhoon conditions, and I believe these birds probably are Bulwer's - the bird in the right hand shot of the first pair is absolutely bang on for Bulwer's in my experience. However, the fork-tail on one is odd and the bill and head-shape seem a bit odd on all but the photo referred to.

Maybe just that element of uncertainty.

Mike Turnbull

Title: Re: Petrels at Po Toi
Post by Yat-tung YU on May 18^th, 2006, 9:04pm

Dear Geoff and others,

Thanks for sharing these interesting photos to us.

However, I think that would not be a Bulwer's Petrel. Tail shape is not good fit to this species and also head and bill shape are also not like the Bulwer's Petrel which I saw before.

I would have another opinion. It would be a Brown Noddy, or a Noddy sp. Tail shape, size (compare to Common and Bridled Terns shown in the pictures), wing shape, head, bill seems good fit to a Noddy.

On the other hand, the fork tailed tern seems not possible to be a Bulwer's Petrel or a Noddy for me.

Geoff: Congratulations! You deserved to see such good bird!

Tung

Title: Re: Petrels at Po Toi
Post by David_Diskin on May 18^th, 2006, 9:53pm

I'm with YYT on this one - well, almost. I believe both of these birds are, in fact, Brown Noddies. Jizz is perfect for this species (apart from the heavily forked tail in the 1st pic of the 2nd bird - but that could be a momentary effect of wind, photo-angle etc,) , and if you look carefully, you can see the white crown in the 2nd picture of the 2nd bird. And also, if you look carefully, it is possible to make out (just!!) the pale underwing with darker margins in the 3rd picture of the 1st bird.

I could be wrong, of course (I usually am!!) but Noddy sp definitely needs to be taken into account in the identification of these birds.

dave diskin

Title: Re: Petrels at Po Toi
Post by miket on May 18^th, 2006, 10:03pm

Every picture except the one I mentioned in my last post does look very wrong for Bulwer's really - must admit, rather embarrassingly, that Noddy just hadn't occurred to me. Does now look like a very likely explanation.

It's actually hard to believe the bird in shot 5 is the same as in shots 1-4 - it looks so much more petrel like than the others.

Mike Turnbull

Title: Re: Petrels at Po Toi
Post by HF_Cheung on May 18^th, 2006, 10:51pm

I agree that photo 1-4 is a Brown Noddy. Size (very similar to Bridled), general colour (brown), posture (Tern-like), fill shape (slightly curved downward), and tail shape (slightly fanned) fit Brown Noddy. In fact, the tail on photo 4 seems to be brush-like. That also fit Brown Noddy well (see the photos on China Bird Photogallery).

However, I do not have sufficient experiences in Petrels.

HF Cheung

Title: Re: Petrels at Po Toi
Post by geoff_welch on May 19^th, 2006, 6:37am

Gentlemen, thank you all for your very stimulating comments. I think it is now worth adding some more about the behaviour of these birds.

I am now reasonably sure both birds are the same species, they looked the same and behaved similarly and any initially perceived difference in size could have been my error. I have at least one long range photo of the birds together, although they did not stay together.

I also believe the birds were terns from their behaviour. Although I have never seen a large petrel or a Noddy, both these birds associated with the large groups of terns which had gathered to feed on the tide line created by the typhoon winds. In fact the second bird spent all its time with Bridled Terns and acted exactly like them in feeding and all other aspects. It was obviously bigger than a Bridled Tern, which is why I withdrew my first id as Bulwers which should be smaller. In fact, I would have called both these birds as terns from the start had I not been trying, once again, to fit a bird to something in The Birds of Hong Kong and South China.

I only have one book with details of Brown Noddy. My only concern was that these birds were all dark with no sign of grey/white on the head. However, it appears that immature Brown Noddy are all dark on the head. My book also shows that Brown Noddy can have a forked tail when the two halves of the 'brush' become separated (I never saw this fork in the field, I was very surprised when I found it on the photo). The fork may also be to do with moulting, the second bird is obviously also missing some wing feathers.

I will now trawl through my other photos to see if anything else is useful (any ideas anyone?), also visit the library to look up Brown Noddy. I understand these birds are present in the Southern Philippines and so could be brought in by the typhoon.

Title: Re: Petrels at Po Toi
Post by Mike Kilburn on May 19^th, 2006, 10:25am

I am persuaded that Noddy is more likely than Bulwer's Petrel, but have never seen either so my opinion is entirely invalid!

I have learned my lesson about commenting on birds I have never seen except for on a small screen on a digital camera!

Cheers
Mike K

Title: Re: Petrels at Po Toi
Post by geoff_welch on May 19^th, 2006, 10:50am

Mike, your opinion is certainly not invalid and your original comments were based on viewing only two photos on a dark 2 inch screen!

I think Noddy did not occur to anyone until Tung mentioned it. That was pure guinness.

Title: Re: Brown Noddy at Po Toi?
Post by geoff_welch on May 19^th, 2006, 11:25am

http://www.geocities.com/geoffwelch46/nt3.jpg http://www.geocities.com/geoffwelch46/nt8.jpg http://www.geocities.com/geoffwelch46/nta.jpg http://www.geocities.com/geoffwelch46/ntb.jpg http://www.geocities.com/geoffwelch46/nte.jpg

Here are some more images of the first bird, I don't know if they add any more but perhaps the 4th one gives a much better view of the bill. I missed it when doing the first set.

I have changed the title to reflect our latest opinion.

Title: Re: Brown Noddy at Po Toi?
Post by Mike Chalmers on May 20^th, 2006, 2:27pm

Dear Geoff,

Just heard Birdline put out the news of Noddies and found your pics. Congratulations again on another first.

There is no doubt that the two birds shown in your pics [assuming all pics are of the same two birds] are noddies. I have seen both Brown and Black Noddies in numbers in Australia and the former also in the Maldives.

Bulwers Petrel is a much smaller and more elegant bird. In terms of body length it is only around 26cm compared to Bridled Tern at around 36cm and Brown Noddy at around 42cm. Although size comparison can be deceptive in photos , your birds appear consistently bigger in terms of both length and wingspan than Bridled Terns. Bulwers is narrow-winged and never shows the broad heavy tail of your birds , which is spot on for noddies. Bulwers is also short-necked, small-headed and small-billed in appearance with a steep forehead typical of other petrels, whereas your birds have long pointed bills on more prominent heads with long sloping foreheads.

The only challenge remaining is to identify positively which noddy. Brown [=Common] Noddy is the largest and heaviest and most likley to occur as it breeds on the disputed islands NE of Taiwan, as well as off the Philippines. The other contender could be Black Noddy which is about 5% smaller and similar therefore to Bridled Tern. Lesser Noddy is smaller again, especially on wingspan, and as an Indian Ocean species is the least likely and can be eliminated on size. In good light Brown Noddy shows contrast between the browner upperparts and dark flight feathers, whereas Black appears more uniformly dark. Brown also has a paler underwing. Neither of these features is conclusive in the photos, but the overall appearance does suggest that upperparts are not as dark as expected for Black Noddy. The details around the head cannot be seen. Indeed, the characteristic pale foreheads and caps are not really visible, although there may be a hint in photo 4 and others as pointed out by Dave. This may just be due to the poor light, or the birds could be juveniles which often have more dusky caps. The main reliable difference on jizz is the bill. Brown has a fairly heavy dagger like bill equal in length to head width with a slight downward curve, whereas Black has a thinner longer bill which looks disproportionately long for the size of the bird. The one or two photos which show bill well indicate a Brown Noddy bill, not Black. In conjunction with the large size, I think there is no doubt that you have seen two Brown Noddies.

The second moulting bird is in tail moult [as well as inner primary moult] with the central feathers missing to give the forked appearance. Noddies have both pre-breeding [partial] moult and post-breeding [complete] moult. Juveniles have a complete moult towards the end of their first year, which seems a reasonable explanation for your second bird. Tropical birds breed at all seasons, but the northern birds breed in our summer.

Well done; what next for Po Toi?

Mike C

Title: Re: Brown Noddy at Po Toi?
Post by geoff_welch on May 21^st, 2006, 2:37pm

Thanks for all your helpful comments.
I will be putting these two birds in as Brown Noddies.

Thank goodness for the digital camera.

Geoff Welch