bean goose (Anser fabalis)
A species of goose; the name is usually written in katakana as ヒシクイ. The kanji 菱食 is ateji based on the bird's habit of eating water chestnuts (菱).
The bean goose is a large goose that migrates to Japan in winter.
I found a flock of bean geese in the rice field.
ガン is the general term for wild geese; ヒシクイ is one specific species.
Katakana spelling is common for this bird name; usually written in kana.
Rare kanji spelling; the character 鴻 means 'large bird' or 'swan/goose' and is not commonly used for this species.
Ateji spelling; literally 'water chestnut eating', referring to the bird's diet. Very rare.
The name ヒシクイ likely derives from 菱 (water chestnut) + 食い (eating), referring to the bird's feeding habits. The exact origin is uncertain.