francolin
Refers to birds of the genus Francolinus, which resemble partridges. In modern Japanese, this is the primary meaning.
Many species of francolin inhabit Africa.
partridge (genus Perdix)
Archaic usage; formerly used for partridges of the genus Perdix. In modern Japanese, 山鶉 (やまうずら) is the usual term.
See also: ヤマウズラ
In old texts, シャコ sometimes refers to the European grey partridge.
Katakana spelling is the most common written form for this bird name.
Kanji form is rare and mainly encountered in older or specialized texts. The word is usually written in kana.
The kanji 鷓鴣 are Chinese-derived characters for francolin/partridge. The reading しゃこ is the Sino-Japanese on'yomi. The exact historical derivation is uncertain.