noun
willow tit
A small bird (Poecile montanus, formerly Parus montanus) found in forests across Eurasia. In Japanese, the name is usually written in katakana.
北海道の森でコガラの群れを見かけた。
I saw a flock of willow tits in a forest in Hokkaido.
The name コガラ (小雀) literally means 'small sparrow/tit', from 小 (ko, 'small') and 雀 (kara, 'sparrow' or 'tit'). The exact derivation is uncertain, but it likely refers to the bird's small size compared to other tits.