和名: ニシオジロビタキ, English: Red-breasted flycatcher, Binomial name: Ficedula parva (Bechstein, 1792)
Wikipedia
スズメ目 > ヒタキ科 > キビタキ属 > ニシオジロビタキ
Order: Passeriformes > Family: Muscicapidae > Genus: Ficedula > Species: F. parvaWikipedia
北西ユーラシア大陸で繁殖し日本には冬鳥として飛来するニシオジロビタキ
オジロビタキ（F. albicilla）、ニシオジロビタキ（F. parva）と撮影個体の特徴を表に示す。 今回の写真から、撮影個体はRed-breasted flycatcher（ニシオジロビタキ）と結論した。
On January 29, 2018, I strolled in Mizumoto Park. In the last visit of the park (Jan. 15), I took pictures of a flycatcher with a camera (DSC-RX10M4) carried for the first preview. F. albicilla and F. parva are similar but I concluded form the photos at that time that the bird would be the F. albicilla. However, I had some objections and then I took photos again with my familiar camera (D810). Characteristics of F. albicilla, F. parva and the photographed individual are shown in the table. From the present photo images, it is concluded that the bird is the Red-breasted flycatcher (F. parva).
以下に、撮影個体の特徴を示す写真と説明を示す。
The photographs and captions showing the characteristics are shown below
オジロビタキ（F. albicilla）とニシオジロビタキ（F. parva）のメスや初冬オスを識別する第一の基準は最長上尾筒の色と言われる。 前回の写真では最長尾筒の色は尾羽とほぼ同じくらい黒っぽく見えた。それが前回この小鳥をオジロビタキ（F. albicilla）とした最大の理由だった。 しかし、今回の写真を見ると、尾羽は濃いこげ茶色だが最長上尾筒の色は明らかに尾羽より薄い。 The first criterion for identifying female and first-winter birds of F. albicilla and F. parva is said to be the color of the longest upper tail-coverts. In the last picture, the color looked almost as dark as the tail feather. That was the biggest reason why I concluded the bird as F. albicilla. However, looking at the photo this time, the tail feathers are dark brown, but the color of the longest upper tail-coverts is obviously thinner than the tail feathers.
(Mizumoto Park, Tokyo, Japan, 11:50, 12:11, Jan. 29, 2018, D810)
オジロビタキ（F. albicilla）とニシオジロビタキ（F. parva）のメスや初冬オスを識別する重要な基準は嘴の色と言われる。 前回の写真では嘴の色は全体が黒っぽく見えた。今回、近距離から下嘴の見える写真を撮れた。今回の写真を見ると、下嘴の基本色は肉色に見える。
Another important criterion is said to be the color of the bill. In the last photos, the color is the bill looked all-dark. This time, I was able to take pictures close look-up of the bill. Looking at the pictures this time, the color of the upper mandible is dark and the lower mandible flesh-color.
(Mizumoto Park, Tokyo, Japan, 11:50, 12:11, Jan. 29, 2018, D810)
体の下面羽衣も識別基準とされる。正面や下から近距離撮影できた。喉は白く、胸は薄い黄土色（バフ色）だ。 首を縮めている時は喉の羽毛が胸の羽毛を覆い境界線ができるが、首を伸ばすとバフ色が連続するように見える。
The underparts consist of the white throat, the warm buff breast and the white belly with a grey wash. When the neck is contracting, the throat feathers cover the chest feathers and a boundary line is formed, but when the neck is stretched, the buff color appears to be continuous.
(Mizumoto Park, Tokyo, Japan, 11:55, Jan. 29, 2018, D810)
木の枝に止まった小鳥をDSC-RX10M4で撮影した。これらの画像はD810で撮影した画像と似ている。前回（Jan. 15）の画像と異なる原因は近距離から 見上げて撮影できたためのようだ。
I took pictures of the bird perched on a twig with the camera DSC-RX10M4. These images are similar to those taken with D810. It seems that the reason why this time of photo is different from the previous image is the photographed condition of looking up and close distance.
(Mizumoto Park, Tokyo, Japan, 12:16, 12:17, Jan. 29, 2018, DSC-RX10M4)
風が吹いて羽毛がめくられた。表面は茶色でも羽毛の根元ほど黒っぽい色であることが分かる。羽毛や光の状態で腹部に灰色のウオッシュ模様が見える のはこのためだろう。飛び立った画像を見るとこげ茶色と白の尾羽、胸側（きょうそく、英：breast-side）が暖色（バフ色）であることが分かる。
The wind blew and the feather of the bird was turned over. It is visible that the base of the feather is darker in color even the surface of the feather is brown. This is why the grey wash is seen on the whitish belly according to the conditions of the feather and the light. Looking at the flight image, it is visible that the tail feather consists of dark brown and white, and that the breast-side is warm color (buff color).
(Mizumoto Park, Tokyo, Japan, 11:55, Jan. 29, 2018, D810)
イギリスでの観察 Observation in England
References: 上記のWeb sites
https://www.birdguides.com/articles/species-profiles/focus-on-can-you-tell-a-taiga-by-its-tail/
韓国での観察 Observation in South Korea
http://www.birdskorea.org/Birds/Identification/ID_Notes/BK-ID-Albicilla.shtml