Where does “ひよこ” come from?

ひよこ (Japanese) comes from Japanese 子, from Japanese 鼠, from Japanese nezumi.

Ancestry of “ひよこ”, step by step

Step	Language	Word	Meaning
1	Japanese	子	a child; a girl, especially a dear or desired...
2	Japanese	鼠	a mouse or a rat; general term for members of...
3	Japanese	nezumi	—