夜や行こう性せい

noun, noun which may take the genitive case particle 'no'

nocturnality; nocturnal

Describes animals or habits that are active at night. Often used as a noun or with の to modify another noun.

• フクロウは夜や行こう性せいの鳥とりです。

  Owls are nocturnal birds.

• 猫ねこは本ほん来らい夜や行こう性せいだと言いわれている。

  Cats are said to be naturally nocturnal.