noun
The normal modern meaning: a swan of the genus Cygnus. Written 白鳥 in general writing and often ハクチョウ in species-name contexts.
冬になると、この湖に白鳥が飛来する。
In winter, swans come to this lake.
子どもたちは岸から白鳥にえさをやった
The children fed the swans from the shore.
noun
white bird
Literal use based on the characters 白 and 鳥, referring to a white-colored bird in general. For an ordinary description of any non-swan white bird, 白い鳥 is often clearer.
「白鳥」は文字どおりには白い鳥を指すこともある。
Taken literally, 白鳥 can also refer to a white bird.