Rarely appears alone - almost always in compounds: 海鸥 ("seagull"), 白鸥 ("white gull"), 鸥群 ("flock of gulls"). The classical poet Du Fu used 鸥 as a symbol of carefree solitude.
鸟 (the bird radical) gives the literal meaning - 鸥 is a bird, specifically the gull. It groups with 鸡 (chicken), 鸭 (duck), 鹅 (goose), 鸽 (pigeon) in the avian family. Simplified 鸟 replaced traditional 鳥 in the 1956 reform.
区 has the alternate reading ōu (still preserved in surname use), which gives 鸥 its sound directly. The same phonetic feeds 欧 (Europe), 殴 (to beat) and 呕 (to vomit) - the qū/ōu family branches off the 区 stem.
