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[雀形目] Narcissus Flycatcher-Owstoni 琉球姬鶲

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发表于 2014-4-22 09:23:30 | 显示全部楼层 |阅读模式
黃眉姬鶲owstoni琉球亚种

香港观鸟会 mbill:





香港观鸟会 ltsunpun:
参考香港及華南鳥類,這鳥不是綠背姬鶲,因為牠眉紋很長,綠背姬鶲是眼先短紋。

偶然在以下網頁看到韓國鳥會有關怎樣辨認黃眉姬鶲的一篇文章:
http://www.birdskorea.org/Birds/ ... atchers-types.shtml
我不是專家,未能看憧全篇文章。無論如何,文章指出黃眉姬鶲包括三個有特色的亞種 - nominate narcissina 黑背,owstoni 硫球和elisae 綠背。
文章最後有附錄例出不同的摘要以附表形式來辨認不同的亞種,由於MBill所拍到的是成年雄鳥,所以我參考附錄裹的成年雄鳥(附表2)來辨別這隻鳥,最後我提議牠是owstoni硫球亞種,原因如下:
-        沒有明顯的眼圈 (elisae 綠背有明顯的黃眼圈)
-        背部和冠顏色多變,由笞蘚色或橄欖色至墨綠色都有 (nominate narcissina 黑背的背部和冠的顏色是黑色的)
-        清楚的黃眉紋 (nominate narcissina 黑背的眉紋是很清楚的橙黃色,但elisae 綠背的眼紋通常是不明顯,或祇有眼先短紋)
-        咽喉黃色 (nominate narcissina 黑背的繁殖羽有火紅色的咽喉)

如有錯漏,請指正。
tpluk

http://www.hkbws.org.hk/BBS/viewthread.php?tid=13897
========================

Owstoni

The little-known owstoni has a much more restricted distribution than narcissina, with breeding believed confined to the Nansei Shoto, a long, curving arc of Japanese islands lying between the main island of Kyushu (Japan) and Taiwan. Long considered a “resident” endemic subspecies (e.g. Brazil, 1991), it has been seldom described in either field-guides or in the birding literature, increasing greatly the possibility of its being overlooked away from core breeding areas. Rather more recently, Otani (2002) considered that although the true status of owstoni still remains largely “unclear”, it was now believed to occur on islands from Iriomote in the south, to Tanegashima (just south of Kyushu) in the north, a range spanning approximately 1 000 km. Additionally, in the north of its limited range it is now known to be largely/entirely a summer visitor, with smaller, shorter-winged birds presumed resident in the south (Otani, 2002). Previously, taxonomic arrangements recognized two further subspecies within the same archipelago: jakuschima from Yakushima (to the north of the archipelago) and shonis from Amami Oshima (towards the center). Both were later considered synonymous with owstoni (see e.g. Morioka et al, 2005), but still also suggest that the geographical variation in owstoni is worth further investigation.

Owstoni is apparently most numerous in subtropical evergreen forest, but can also be found occasionally in remnant forest patches, in dense cover in degraded secondary forest and sometimes at more open forest edge (e.g. Fergus Crystal, in lit. 2004; Sean Minns, in lit., 2004). Birds Korea has not yet been able to trace population estimates, but it appears to be rather scarce, and considering the extent of habitat loss and degradation on many of the islands, it is most likely of Special Conservation Concern. According to Brazil (1991) owstoni was formerly described as “common…at very low altitudes” but subsequently had “become very uncommon on Amami-Oshima and Okinawa…no birds were heard on territory for several years in the mid-1980s”. Otani (2002) also states that “the population is thought to be small; it is restricted to small islands and at least on Amami-Oshima, Okinawa, Ishigaki and Iriomote… its density is not high”. In contrast perhaps, in 2004 no less than 50 singing males in total were estimated heard along a route taken between Ohara and Uehara on Iriomote, between March 25th and 26th (Fergus Crystal in lit., 2004).

As owstoni is not a sedentary taxon - but rather a short-range migrant in the north of its range – it is only to be expected that it will occasionally be recorded away from the Nansei Shoto. It has, for example, been recorded in Taiwan (Fig. 3), in Kyushu (see Figs.23-27 in identification section below), and at least once in western Honshu, with a Second Calendar-year male photographed in Masuda City, Shimane Prefecture on May 2nd, 1999 (Ishimoto, 2005).

More surprisingly, however, owstoni has also strayed to South Korea. Apparently two different Second calendar-year males were photographed in April 2001 on Gageo Island (at approximately 34 D 05 N, 125 D 05 E) - one by Charlie Moores and NM on April 26th, 2001 (Fig. 28-29), with a second individual two or three Km distant and several days apart by Park Jin-Young (Fig. 30). In addition, there have been one or more further probable owstoni noted by NM in South Korea, both green-backed “female-types’: one with yellow specks coming through on the rump (Gageo Island between May 9th and 11th, 2000), and one with yellow-looking, frayed uppertail coverts photographed on Eocheong Island (at approximately 36 D 10 N, 125 D 58 E) on May 10th, 2004 (Fig. 31). Gageo Island (often named So-Heuksan on maps) is approximately 1 000 km due north of Iriomote (across open sea), and at least 500 Km removed from any known breeding islands. It seems possible that these individuals, if correctly identified, could have been drifted north to Korea by strong southerly winds, produced by low-pressure systems tracking west in spring across the East China Sea.

Considering the frequency of such weather systems and the recent records to the north and northeast of its breeding areas, it seems quite possible that owstoni could occur in spring significantly north of its presently mapped breeding range with some regularity - perhaps especially on islands off the west coast of Kyushu and western Honshu, in Korea along the south coast and on the southwest islands, and even northwest to the Chinese coast?

http://www.birdskorea.org/Birds/ ... atchers-types.shtml

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发表于 2014-4-22 17:55:27 | 显示全部楼层
2014年4-18号,如东小洋口小树林






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发表于 2014-4-25 17:01:19 | 显示全部楼层
本帖最后由 上善若水 于 2014-4-25 17:03 编辑

我也来贴二张亚成鸟,2014/04/24 小洋口的




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