一羽(いちわ)

Counter for birds and rabbits. Though rabbits are mammals, they have been traditionally counted with 羽(わ) rather than 匹(ひき); one common explanation is that Buddhist monks, forbidden from eating four-legged animals, rationalized eating rabbits by classifying them as birds. In modern usage, 匹(ひき) is also widely accepted for rabbits.

COUNTING PATTERN (sound changes):

• 一羽(いちわ) (1)
• 二羽(にわ) (2)
• 三羽(さんば) / さんわ (3) — both readings used
• 四羽(よんわ) (4)
• 五羽(ごわ) (5)
• 六羽(ろっぱ) (6) — note っ and handakuten
• 七羽(ななわ) (7)
• 八羽(はちわ) / はっぱ (8)
• 九羽(きゅうわ) (9)
• 十羽(じゅっぱ) / じっぱ (10)
• 何羽(なんば) / なんわ: how many birds?

Usage

• Used for all birds: 鶏(にわとり) (chickens), 雀(すずめ) (sparrows), 鶴(つる) (cranes), 鳩(はと) (pigeons), 鴨(かも) (ducks), etc.
• Also traditionally used for 兎(うさぎ) (rabbits), though 一匹(いっぴき) is increasingly common in everyday speech.
• Not used for other flying creatures: bats (蝙蝠(こうもり)) take 匹(ひき), and insects take 匹(ひき).

Similar words

• 一匹(いっぴき): one (small) animal — general counter for mammals, fish, insects, and now often rabbits.
• 一頭(いっとう): one (large) animal — used for larger mammals like cattle or horses.