查看完整版本: Recent RC decisions

cgeoff 18/02/2011 15:22

Recent RC decisions

The following decisions were made at the two most recent meetings of the Records Committee.

[u]28th September 2010[/u]

The status of four species previously in Category B of the HK List, Pale Blue Flycatcher, Blue-throated Flycatcher, Grey-necked Bunting and Chestnut-tailed Starling, and two in the old Category E, Eurasian Collared Dove and Azure-winged Magpie, were reviewed to determine their category in the new list.

The single record of Pale Blue Flycatcher (6th April 1991 at Tai Po Kau) was reviewed based on an analysis of the species known distribution in China. The main concern was that a single record in spring of a male flycatcher from south west China was contrary to the pattern of records in Hong Kong of other flycatcher species probably originating in the same area e.g. Rufous-gorgeted Flycatcher and Small Niltava, which have been of winter occurrence. The current record was therefore considered at least as likely to concern an ex-captive bird as a wild individual, and it was decided to move the species to the new Cat III (equivalent to old Cat E).

In a similar analysis, the single record of Grey-necked Bunting (17th March 1990 at Mai Po) was considered contrary to the pattern of occurrence of Black-headed and Ortolan Bunting, which have been almost exclusively of autumn/winter occurrence in Hong Kong. The current record was therefore considered at least as likely to be an escaped bird as a wild bird and it was decided to move the species to the new Cat III (old Cat E).

Blue-throated Flycatcher [i]Cyornis rubeculoides [/i]has been split by the International Ornithological Congress, into two species. The taxon occurring in Hong Kong is Chinese Blue Flycatcher [i]Cyornis glaucicomans[/i]. This species therefore replaces Blue-throated Flycatcher in Category I of the new Hong Kong list. A review of recent records of this species currently under way may confirm or change this position.

Both Eurasian Collared Dove and Azure-winged Magpie were transferred to Cat IIB on the new HK List based upon self-sustaining populations of both species within Hong Kong.

With the addition of two species and the reduction of two species, the HK List remains the same at 502.

It was agreed to review all records of the following species to determine whether any changes need to be made to their status – Red-breasted Flycatcher, Plain-tailed Warbler, Grey-crowned Warbler and Ruddy Sparrow.  

[u]26th January 2011[/u]

Four potential new Hong Kong records were reviewed – Eurasian Roller, Tundra and Taiga Bean Geese (two species) and Red-headed Bunting. The reviews were based on photographs and other materials on the website as well as submitted records.

[u]Eurasian Roller, 5th October 2010[/u]. Species identity was agreed unanimously, and the bird was aged as a first-winter. Discussion centred on the possibility of its being an escape. Given the absence of significant feather damage in any of the excellent photos, the presence of other western species in Hong Kong at the same time (Blyth’s Reed Warbler, possible Siberian Stonechat [i]maura[/i], Rosy Starling), a Hong Kong Observatory Backward Trajectory Map for 2010-10-04 indicating an air mass origin in a main area of occurrence of the species and the suitable date for western vagrants, there was unanimous acceptance of this species to the HK List as Category I.

[u]Tundra and Taiga Bean Goose[/u] (two species), 1st January 2009 and 3rd November 2010. IOC accept two species, Tundra Bean Goose ([i]Anser serrirostris[/i]) and Taiga Bean Goose ([i]Anser fabalis[/i]). There are, however, different subspecies in the Western ([i]A.s.rossicus[/i] and [i]A.f.fabalis[/i]) and Eastern Palearctic ([i]A.s.serrirostris[/i] and [i]A.f.middendorffii[/i]). In the absence of any authoritative papers on identification of the latter two subspecies, the Committee agreed on the following list of identification criteria and it was on this basis that the two recent records were assessed.

Tundra Bean Goose [i]Anser serrirostris/rossicus [/i]
•         Short, quite thick looking neck
•         Large head relative to overall size
•         Rather angular (‘lumpy’) head
•         Shorter, conical bill
•         Obvious angle between head and bill
Taiga Bean Goose [i]Anser fabalis middendorffii [/i]
•         Long slender looking neck
•         Well proportioned head
•         Less angular head shape
•         Longer slender bill
•         Less pronounced angle between head and bill
•         Combined, these features can result in a rather Whooper Swan like structure

Note: there is no significant difference with regard to the depth of the grinning patch when dealing with eastern taxa (unlike western taxa where there are consistent differences).

[u]Record from 2009-01-01[/u]. Species identity was agreed as Tundra Bean Goose on the basis of bill size and shape, head size and shape and neck length. It was unanimously agreed to accept this species to Category I of the HK List as.

[u]Record from 2010-11-03[/u]. This involved four birds. The earlier sighting of three birds dated 2010-10-30 was recognized to be three from the same group but photographs taken at the time were insufficient to identify the specific species. Of the four birds from the 2010-11-03 record, two could be positively identified as Taiga Bean Goose, one as Tundra Bean Goose and one was unattributed, as it showed characteristics of both, not an uncommon feature of Bean Goose according to the literature. It was unanimously agreed to accept Taiga Bean Goose to Category I of the HK List in.

[u]Red-headed Bunting[/u], 23rd December 2010 (Long Valley) and 27th December 2010 (Lam Tsuen). Species identity was agreed unanimously for both as Red-headed Bunting. Ageing as first winter for the Long Valley bird and adult for the Lam Tsuen bird was possible. Discussion then centred on the possibility of escape for each record and included reference to the first HK record of Red-headed Bunting (2008-1-10 at Mai Po), which resulted in the current designation of the species as Category III.

[u]Record from 2010-12-23[/u]. This bird showed extensive abrasion to the tail feathers with some small pieces missing, although the flight feathers appeared in good condition. This combination was considered by some as unusual for a wild bird, which would be expected to show equal abrasion across all feathers. The vote was 4/1 in favour of retaining the existing status of Red-headed Bunting as Category III.

[u]Record from 2010-12-27[/u]. This bird showed all feathers in pristine condition which indicated a recent moult, as would be expected for a winter moulting species. Considerable discussion followed concerning the date of the record and whether this was consistent with a wild bird of far western origin. On the negative side, all HK records to date are for December/January which would be an unusual date for arrival of a western vagrant and quite different to Black-headed Bunting where the substantial majority of records are for October/November; in addition, the bird was relatively tame. On the positive side, the feather condition did not indicate a cage bird and it may have either been in the area since autumn or be relocating after an earlier arrival further north. The eventual vote was 3/2 in favour of retaining the existing status of Red-headed Bunting as Category III, although this was recognized as a conservative view, and the status of this particular record would be re-opened if further HK records of Red-headed Bunting changed the picture.

With the addition of three species, the HK List now stands at 505. The official numbers for the new additions will be announced later.
Geoff Carey
Records Committee Chairman

[[i] Last edited by cgeoff at 18/02/2011 15:24 [/i]]

Record_Com 28/02/2011 18:22


[b]藍喉藍鶲[/b] ﹣此鳥種根據《International Ornithological Congress (IOC)》已被分為兩種,而在香港出現的品種被鑑定為中華仙鶲,並代替了香港鳥類名錄中的藍喉藍鶲。我們將進一步審核相關紀錄以確認兩者在香港的出沒情況。
[b]灰斑鳩及喜鵲 [/b]﹣兩者皆在香港建立了穩定的群落,因而納入新鳥類名錄的IIB類。

短嘴豆雁 (Tundra Bean Goose [i]Anser serrirostris[/i])
豆雁 (Taiga Bean Goose [i]Anser fabalis[/i])
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