灰色雁

From 灰色(はいいろ) (haīro, “gray”) + 雁(がん) (gan, “goose”).

灰(はい)色(いろ)雁(がん) or 灰色雁(ハイイロガン) • (haiirogan) ^{←はひいろがん (fafiirogan) or ハヒイロガン (fafiirogan)?}

1. greylag goose, Anser anser

As with many terms that name organisms, this term is often spelled in katakana, especially in biological contexts (where katakana is customary).