しろはらとうぞくかもめであれば
白腹盗賊鴎であれば
shirohara tōzokukamomedeareba

Noun
Da Copula

The "-eba" conditional form ("if/when…") of しろはらとうぞくかもめ

1. If it were a white-bellied pirate gull; If a white-bellied pirate gull existed

Ba Conditional
Usually Written in Kana