tsheunglai

Foreword:



The writer, taking opportunity of proximity of Mai Po Boardwalk for gull observation in spring, undertakes personal gull observation and makes individual gull studies aiming at full or approaching full identification. Heavy reference is made on the Japanese
father and son 氏原巨雄,氏原道昭s' A Gull Identification Handbook Revised Edition of year 2010.

A reminder which is thought appropriate to anyone who uses the handbook is that gulls which appear in February to April in Hong Kong must have been under Tropical sunlight for months henceforth exhibiting bleaching effect or appearing paler in coloration of plumage so much so that immature birds almost always look paler than those drawings done by the Japanese authors.

The following depictions are undertaken with the purposes first of all to help me fix the details of what I have seen in memory, a kind of
refreshing that achieve permanence of learning in my mind, and secondly to arouse greater interest in those who have less experience than me but happen to be interested in gulls as well.

S L Tai

[ Last edited by tsheunglai at 15/02/2013 18:38 ]

tsheunglai

14th February 2013

Gull One

I was told of its presence but I had been careless enough to see but missed it enough not to concentrate on when I swept my spotting scope twice across, an Swarovski HD 80 with a x30 eyepiece of older version, thinking that it was just another ordinary big gull until a fellow birder/photographer told me the gull's location.

Here is the impression I got of that gull.

It had the outlook of a large gull, full bodied with a heavy keel, making legs to appear short and bill heavier than that of a Black-headed's. But on closer look in good sunlight along the waterline at two metre hightide it had the following appearance.

It had a slopy forehead similar to Black-headed gulls' nearby and was white in colour. However, the crown is quite closely streaked brown, but if one looked at the face it was whitish on the frontal half but made darker with brown steaks again on the hind-part half. At an acute angle with a complete sideway position even the white face part appeared washed grey. Hind parts of the head and neck were also steaked brown.

The breast was overall white but smeared with vague blotches of pale brown marks. The brown marks became less dense towards the bottom of belly but blotches become almost lateral lines when looked upon sideways on the undertail coverts and looked denser. It was later observed that the upper tail coverts had light brown marks as well and the tail had a wide dark brown band with the same colour intensity as those seen
on fold primaries of the darkest kind of brown.

Now the fold wings. They were covered on top by pale grey scapulars which looked thick. All the wings coverts were whitish with widely scatterd pale brown marks which contrasted strikingly with the large tertails that were brown centred with thin pale fringes.

The bill was two toned, solid black of about two-fifths towards tip and three-fifths dull pink towards base. The legs of the bird on walking near bare mud looked dull pinkish.

I will post the name and age of the gull tomorrow and a summary with salient points that faciltate quick identification.

S L Tai

[ Last edited by tsheunglai at 14/02/2013 21:11 ]

tsheunglai

Summary of the observed features of Gull One

The gull deems to be a first winter Mew gull, Larus canus, kamtschatschensis.

Size: Objective measurements are impossible. In comparison it seemed that it was body speaking slightly smaller than Eurasian Curlews nearby but somewhat 80% larger than the Black headeds present.
      A Field Guide to the Waterbirds of Asia states it is 45 cm long as compared to Black headed's 40.5.

Bill: It two-toned bill thicker and longer than a Black headed's is helful.
Streaking: The moderately heavy brown streaking on the crown and hind-part of face and neck and neck-sides are important.
Coverts: The pale grey scapulars are a key feature of a first winter, and the striking contrast between upper wing coverts with the brown but pale fringed tertials seals its identity.
The tail with its tail coverts and dark band are just routine checks as nearly all first winter gulls have dark tail bands.

S L Tai

NB Thomas Chan has posted two photos of the same bird today or last night. The bird looks even paler than what I saw, obviously under
   strong sunlight.

tsheunglai

27th Feb 2013

Gull 2

With high tide at Deep Bay being 2.05m, I went out again to the new boardwalk bird hide to observe gulls again.

It was the second big gull I concentrated upon, resulting in the details below.

The immature gull looked the darkest one within sight of my spotting scope.

The bill was two-toned, dark tipped and graduated into some dull kind of pink with no sharp demarcation. The legs were pink and eyes black, usual features of an immature/first winter bird.

The head was only clearly lined with thick streaks on the hindneck, though crown looked washed brown of the slightest tone, suggesting where brown streaks had been.

The upper body was uniformly pale heavily mottled with brown centres, tertials largely brown with pale tips having short-shaft-arrow shaped centres. The exposed primaries of its folded wing were darkish brown. Looking upon from several different directions as it moved, there there no grey tinge discerned on the wing coverts or scapulars. The front part of its flanks also mottled or clouded with pale brown.

When compared with an adult Heuglin nearby, the bird looked a bit larger and short in body.

A summary will follow tomorrow.

S L Tai

[ Last edited by tsheunglai at 27/02/2013 21:23 ]

tsheunglai

Summary of the observed features of Gull 2

The gull deems to be a first winter Vega, Larus vegae.

Size: Slightly larger than a Heuglin nearby.

Bill: in coloration it greatly resembled that of a first winter Slaty-backed, Larus schistisagus. However, being beware the latter's bill is in general heavier/thicker so it was thought the bird not to be the latter.

Streaking & coverts: Again there's a lot of similarity between the first winters of vegae and schistisagus. The fine points are the exposed primaries of fold wing of the gull in question that were a lot darker - in fact the darkest of the upper body - together with the stated/observed key features of its tertials again rule out the latter.

In general, the first winter bird was not heavy-bodied as a Slaty-backed, nor its face as smeared by streaks or irregular dark patches
as the latter - described as the face having been punched by Y Y Tung one of our best Chinese gull observers if not the best - help to tip the bird overwhelming to be a Vega.

Again bleaching effect resulting from sunlight upon the bird has affected my judgement.

S L Tai

NB In the Japanese book the authors have especially give direct comparison of the two species in drawings as well as in a good photo regarding first winter plumage.

[ Last edited by tsheunglai at 28/02/2013 19:38 ]

tsheunglai

27th Feb 2013

Gull 3

The big-sized gull was swimming facing directly away from me when I first sighted it.

The bill was two-toned, black tipped and the rest unclear pink. Its head was otherwise quite clear white with vague remnants of brown
streaking, evidence of sun bleaching effect. There were broad light brown streaking on the breast, the wing coverts were pale or whitish.
The exposed part of folded primaries looked brown with fine white tips. What impressed me most were the tertials looking longish with central brown patches ending in broad white tips.

The bird looked thicked or short necked.

S L Tai

tsheunglai

Summary of the observed features of Gull 3

The gull is in high probability a second winter Vega Larus vegae.

Bill: my notes on the drwawing of the gull in question indicates inner pink part could be dull and clear, a favourable point.
Streaking: Broad light brown streaking on the breast again favours it to be vegae.
Exposed primaries: They were deep brown not blackish of a Heuglin of the same age put more weight on being vegae.
Tertials: very wide white tips on otherwise pale brown centred feathers, together with light grey scapulars giving the bird all together a warm and light coloured 2nd winter.

S L Tai

[ Last edited by tsheunglai at 7/03/2013 17:43 ]

tsheunglai

27th February 2013

Gull 4

The gull was seen among adults Heuglins but with a two-toned bill black/darkish tip taking up about two-fifths of the length, rest being pink. The eyes looked black. The legs were pinkish.

Dense thin but dark streaks appeared on hindneck below an otherwise white head. As regards plumage, the darkest part being the deep brown tertials and half of tail-length end-band with inner half of upper tail spotted dark. The scapulars, sparsely distributed with brown-spot centred feathers, appeared pale grey, obviously lighter than adult Heughlins. Medium coverts, basically white, were having the same degree of brown centred feathers. The greater coverts were also brown-centred feathers. Underbody overall white but with light brown streaks or spots thinnly distributed on flanks and belly.

S L Tai

[ Last edited by tsheunglai at 6/03/2013 20:46 ]

tsheunglai

Summary of the observed features of Gull 4

Observing gulls needs comparison and noting more than one or two features for certainty. Even then insufficent information and
experience might lead to failure to identify.

The bird in question is judged to be a second winter Heuglin.

The clearly defined tones of the bill, the dense thin but dark streaks on hindneck are helpful pointers. Together with other features stated previously, the bird was quite safe to be regarded as a second winter Heuglin.

S L Tai

[ Last edited by tsheunglai at 7/03/2013 18:15 ]

tsheunglai

Gull 5 seen also on 27th February 2013

The bird had dark tipped bill with rest being pink. The pink legs were lighter in hue than nearby Heuglins. The eyes were dark and tame looking. The scapulars also looked some grades lighter in grey than the Heuglins. What struck an observer was that the upper two tertials were grey with wide white tips while the lower ones were white-fringed with light brown centres. The great coverts were lightly brown
centred in streaks. The exposed primaries were white tipped. The hindneck was streaked in light brown. The underbody were quite clearly white except some brown marks near/around the shoulder and near the belly side.

S L Tai

tsheunglai

Summary of the observed features of Gull 5

Heavy weight nearing certainty is in favour of the bird being a 3rd winter Vega gull Larus vegae.

The light grey tone of the scapulars, the defined two-toned bill and the overall light brown streaking on the body are favourable
features. What tips the conclusion towards a third winter vegae is the tertails' colour patterns that have greatly helped me.

S L Tai

tsheunglai

14th March 2013

Gull 6

The gull looked every bit an adult. Mainly a white and grey gull;the white part bare of streaks and grey parts uniform  one or two shades lesser than a Heuglin's.

It's interesting to find it had a beady eye, no dark shades around the eye and therefore looks small. The bill was had four tones,at near-distance a small dull red mark at the tip top followed by a fairly larger part of black and again fringed by a small dull red and the rest a dull greenish yellow. The legs were again ill-defined, vaguely resembling somewhat a mixture of greenish and pink.

The scapulars and wing coverts were concolorous with tertials thinnly fringed white. The tail had a broad subterminal black band fringed by a thin white tail-end one. The exposed primaries were all black with no white tips or mirrors.

S L Tai

[ Last edited by tsheunglai at 15/03/2013 21:14 ]

tsheunglai

Summary of the observed features of Gull 6

The size of the gull in question - which I deliberately omitted to make its identity more intriguing - the height of its back was roughly half the full stature of a large gull nearby, together with its broad black tail band bordered by white tail-end, were evidences enough to tell it being a Black-tailed gull, Larus crassirostris. What makes it an object worth of further observation is the determination of its age.

It is, with the help of the Japanaese handbook, a third summer Black-tailed. It's absence of any white marks near primary tips, brown body streaking, especially on hind neck and crown, paler overall grey, duller colours of its bill, and an almost indeterminable colour tone of its legs all helps to tell it from a non-breeding adult.

S L Tai

[ Last edited by tsheunglai at 17/03/2013 19:32 ]