noun
first Japanese bush warbler song of the year
A seasonal word (kigo) for early spring, referring to the first song of the Japanese bush warbler (uguisu) heard in the new year.
今年の初鴬を聞いて、春の訪れを感じた。
Hearing the first bush warbler song of the year, I felt the arrival of spring.
Refers to the Japanese bush warbler itself, while 初鴬 specifically means the first song of the year.
Compound of 初 (hatsu, 'first') and 鴬 (uguisu, 'Japanese bush warbler'). The reading はつうぐいす follows standard rendaku rules.