名词眉部; 眉纹，眉（毛）
1. In both photos, the supercilium appears to reach the bill base, pointing away from Arctic.
在这两张照片中，眉斑看来皆往前延伸到嘴喙的基部，这点便和极北柳莺不同。
2. Supercilium of Arctic usually clear and contrasty, white, long and flared and kinked at rear, not so on this individual.
极北柳莺的眉线通常很清楚且反差强烈、白色、长、呈喇叭状、扭结在后面，这只柳莺并没有这样。
3. The majority of Arctics to my eye seem to have ochre-toned legs, and the supercilium does not reach the bill (which can be very hard to judge in the field).
在我看来大多数的极北柳莺似乎有黄土色的脚，且眉线没有到达喙。
4. Although the important crown and undertail covert details are not clear in this photo, the face is rather featureless with a poorly-defined eye-stripe and supercilium.
虽然重要的特徵－冠羽与尾下覆羽的细节在这张照片并不清楚，但这张「没什麼特色」的脸有著对比不明显的眉斑和过眼线。即暗示是艾吉柳莺
5. Also `some` of the supercilium appears to continue above the bill, albeit rather diffusely (not the case in Arctic, but OK Willow).
有部分的眉线似乎一直往前延续到嘴的上方，尽管那部分相当的扩散（极北不会这样，但欧柳莺可以是这样）。