考题继续：渔鸥？红脚银鸥？ 主题选项

[野鸟]

渔鸥？

附加图片

EXIF: 1/305, F5.1, 0/10EV, ISO100, 32mm, @ 2005:01:08 09:14:09, E4500

 

[ptarmigan]

余日冬认为最后一张中的“它是（）鸥”的答案——灰背鸥的第一冬
因为他无法输入中文，我代为翻译如下：
理由1 深粉红色的脚－银鸥类未成年鸟的脚是较浅的粉红色
理由2 与银鸥类相比，嘴短而厚，且几乎全黑，仅基部有少部分粉色
理由3 背部羽色与翼覆羽的颜色有区别，前者色更深
理由4 眼周深色

但是他也指出，还有一些关键特徵从此图中看不出来
包括：翅膀长度－灰背鸥看上去翅膀很短
胸腹部应该显得很壮实
深色的尾部－灰背鸥的尾羽几乎全黑，或仅仅在基部有一小块区域白色，而银鸥类未成年鸟尾羽基部白色区域更大
原文如下：I am almost sure that this is a first winter Slaty-backed Gull. Reasons:
1) Deep pink legs – not pale pink as legs shown in other juvenile Herring Gull spp.
2) Black, short and think pink – good comparison with other Herring Gull, bill is shorter and thicker and almost all black (only small part of base is pinkish).
3) Difference between mantle feathers and wing coverts – You can see that mantle feathers are in different colour and patterns than the wing coverts. Also, the colour of mantle feathers must be darker than the wing coverts.
4) Dark area around eye – areas around eyes are always darker.

Missing information – Actually, there are two more criteria for 100% identification but these cannot be shown in this picture.

1) wing projection – Slaty-backed Gull is in a short-winged structure and wings seem short. It also makes an appearance of a very compact body.
2) Heavy breast and belly – It has a ‘pot-bellied’ appearance and also shows very strong breast.
3) Dark tail – Tail is almost totally black, or only small area on the base of the tail is white. That is different to Herring Gull spp. that could show some white area on the base of the tail.