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Subject: Hong Kong waters, spring 2014 [Print This Page]

Author: lrichard Time: 26/04/2014 15:22 Subject: Hong Kong waters, spring 2014

Birds seen on a boat trip Aberdeen-Po Toi-Soko Islands-Aberdeen, 26 April 2014

Streaked Shearwater 3
Sooty Shearwater 1 (potential HK 1st record)

Long-tailed Skua 4
Arctic Skua 6
Pomarine Skua 4
skua sp 3

Ancient Murrelet 3

Whiskered Tern 1
White-winged Tern 24
Greater Crested Tern 11
Little Tern 10
Common Tern 19
Aleutian Tern 117
Black-naped Tern 7
Bridled Tern 1

Red-necked Phalarope 40
Ruddy Turnstone 1
Red-necked Stint 8

Reef Egret 4
Little Egret 4
Cattle Egret 20

Barn Swallow 8+
Yellow Wagtail 22

Author: JamesLambo Time: 26/04/2014 18:33

Thanks for posting this Richard

A minor correction - 4 Ancient Murrelets - a single, then later a group of three.

Cheers

James

Author: wleepoin Time: 26/04/2014 19:53

The shearwater in Question

Cheers
PWMK

Author: lchunfai Time: 26/04/2014 21:15

Thanks for a nice trip and this is the same bird:

Author: twallace Time: 26/04/2014 22:00

Many thanks all experts & PWMK

Long-tailed Skua

Pomarine Skua

Arctic Skua

Sooty Shearwater ?

Streaked Shearwater

Greater Crested Tern

Ancient Murrelet

Author: ddavid Time: 26/04/2014 22:00

I've been looking at a few photographs of shearwaters on the Internet and am wondering if the underwing pattern of this bird as it appears in the posted images really rules out Short-tailed Shearwater.

David

[ Last edited by ddavid at 26/04/2014 22:49 ]

Author: John Holmes Time: 27/04/2014 15:07 Subject: May 2008 Short-tailed Shearwater

For comparison with the potential Sooty Shearwater, here's a shot of Short-tailed taken in HK southern waters six years ago

Image Attachment: [underwing] STShearMay08.jpg (27/04/2014 15:07, 87.02 KB) / Download count 615
http://hkbws.org.hk/BBS/attachment.php?aid=18112

Author: lpaul Time: 27/04/2014 15:33

I don't think the underwing pattern really fits either species perfectly. It is very pale for Short-tailed and the primaries don't seem to be dark enough for Sooty. However, for such a pale underwing, the underparts seem to be dark for Short-tailed. The bill seems rather long which favours Sooty. The forehead seems rather steep which favours Short-tailed. What is very compelling for me though is the tail, this is clearly long and wedge shaped, which seems to eliminate Short-tailed.

Author: John Holmes Time: 27/04/2014 17:12 Subject: Shearwater in HK southern waters, 26th April 2014

FWIW here are three shots I took of the shearwater under discussion.

It does look relatively long-billed and long-tailed, especially in the first photo.

Image Attachment: 140426_jjh01.jpg (27/04/2014 17:12, 73 KB) / Download count 614
http://hkbws.org.hk/BBS/attachment.php?aid=18113

Image Attachment: 140426_jjh02.jpg (27/04/2014 17:12, 66.31 KB) / Download count 655
http://hkbws.org.hk/BBS/attachment.php?aid=18114

Image Attachment: 140426_jjh03.jpg (27/04/2014 17:12, 60.03 KB) / Download count 590
http://hkbws.org.hk/BBS/attachment.php?aid=18115

Author: John Holmes Time: 27/04/2014 18:19

And here are a couple of shots of Sooty (I believe) Shearwater from the southwest Pacific Ocean in April last year.

Image Attachment: wpo3_10.JPG (27/04/2014 18:19, 55.24 KB) / Download count 635
http://hkbws.org.hk/BBS/attachment.php?aid=18116

Image Attachment: wpo3_11.JPG (27/04/2014 18:19, 63.53 KB) / Download count 629
http://hkbws.org.hk/BBS/attachment.php?aid=18117

Author: thinfor Time: 28/04/2014 08:14

Very productive n great find. Congratulations.

Author: JamesLambo Time: 28/04/2014 17:45

Dear ID-ers

I asked a very experienced seabirder/pelagicist friend of mine in Australia (Roger McGovern) to comment on the ID conundrum of the mystery shearwater seen on this trip. He said that:

Having looked at your bird, I am inclined to say that it is a Short-tailed [...] The bill does not look long and slender enough for a Sooty and the steep forehead suggests Short-tailed rather than Sooty. The white underwing flash extending into the secondary coverts also points to Short-tailed, as does the absence of dark streaking in the coverts. It would have been nice to have a photo showing the feet extension or lack thereof, as clear feet extension would be another strong point in favour of Short-tailed. In the field, I find the flight pattern very useful as Short-taileds tend to fly in short bursts of rapid wing beats (a bit like Flutterers and Huttons) whereas Sootys glide a lot more in the way of Wedge-taileds.

Roger also pointed out that: "The question of sorting Short-taileds and Sootys when they are in ‘overlapping’ plumages is a vexed question which leads to a lot of discussion at the highest level of expertise!" and referred me to a discussion on the Birding Australia mailing list about a photo of a shearwater off Wollongong in January 2012 which was first identified by Nikolas Haass (one of our most knowledgeable field ornithologists in Australia) as a Sooty, but that after much discussion, the consensus was that it was actually a Short-tailed.

I read through the discussions of the Australian bird and have summarised the information on IDing these two birds.

UNDERWING: Short-tailed: shiny underwing with little contrast; especially on the under primary coverts; more silvery, reflective-looking background; low contrast between the the shiny primary bases and the coverts.
Sooty: shows dark streaks which contrast sharply with the very white background; has clearcut areas of dark pigment.

These features can be really hard to be sure of in the field, because they are so light dependent. In the hand they are always easy to tell Sooty and Short-tailed apart, even ignoring measurements, just by the colour of the underwing. However, seeing that in a reliable way in the field is extremely difficult and hugely lighting dependent, so it's very easy to be mislead, even if you know exactly what to look for.

BILL: Short-tailed: small, "cute"-looking, appears 'glued on'.

HEAD: Short-tailed: head small, neck short, forehead steep, almost vertical forehead; has a hood.
Sooty: sloping forehead (though even a Sooty can show a steep forehead).

TAIL: Short-tailed: small/short tail, and long foot projection.

STRUCTURE: Sooty: combination of a relatively muscular body and very long pointed wings.

FLIGHT STYLE: (See Roger's comments above). But one commentator maintained that "Flight style is important - it's often how we pick up something different. But even ignoring human subjectivity, flight style is obviously not a fixed character. See how much wind strength can affect it! So should it be relied upon to identify a rarity? I'm a skeptic. It doesn't constitute any useful evidence in my view. It may be the bird is genuinely different in flight for some perfectly rational (but unknown) reason, or it may just be that people think it looks different due to some illusion, or worse, because someone else said it did. Often it comes down to the question of whether a bird looks different because it is a different species, or for some other reason. It might be just hungry or fat!"

A final caveat was that none of these features are definitive by themselves, and that pictures of both species showing and not showing these features could be found, and this underlines the fact that we always need to look at a combination of field marks.

James

Author: wleepoin Time: 29/04/2014 20:26

Arctic Skua

Long-tailed Skua

Pomarine Skua

Without doubt, it was an excellent day !

Cheers
PWMK

Author: lrichard Time: 3/05/2014 14:54

Hong Kong waters, spring 2014

Birds seen on a boat trip Aberdeen-Po Toi-Aberdeen, 3 May 2014

Cattle Egret 7
Red-necked Phalarope 41
Aleutian Tern 6
Black-naped Tern 6
Bridled Tern 2
Little Tern 7
Whiskered Tern 3
White-winged Tern 10

Author: lrichard Time: 10/05/2014 17:10

Hong Kong waters, spring 2014

Birds seen on a boat trip Aberdeen-Po Toi-Aberdeen, 10 May 2014

Short-tailed Shearwater 1

Great Crested Tern 3
Aleutian Tern 13
Common Tern 13
Bridled Tern 2
Black-naped Tern 8 (all off Lamma)
Little Tern 1
White-winged Tern 8

Red-necked Phalarope 223

Author: lrichard Time: 17/05/2014 15:59

Hong Kong waters, spring 2014

Very disappointing today (17 May 2014), with only the following birds seen on a boat trip Aberdeen-Po Toi-Waglan-Aberdeen:

Whimbrel 5
Red-necked Phalarope 6
Bridled Tern 16
Black-naped Tern 11

Pacific Swift 6, all at Waglan

Author: lrichard Time: 25/05/2014 14:45

Boat trip Aberdeen-Po Toi-Waglan-Aberdeen, 25 May 2014

Short-tailed Shearwater 1

White-winged Tern 10 (near Waglan)
Black-naped Tern 4 (Waglan)
Bridled Tern 8

no phalaropes

Pacific Swift 2 at Po Toi, 16 at Waglan

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