As you might guess, the seagull is an important symbol that recurs throughout Chekhov's play, The Seagull. No huge shocker there. Nina calls herself a seagull. Konstantin shoots one and leaves it lying around for Trigorin to find. Trigorin then recognizes a great image when he sees one; the seagull gives him an idea for a story about a girl much like Nina.
The innocence and freedom of a bird in flight is a recurring image in Chekhov's other plays as well (think migrating cranes in Three Sisters). In The Seagull a play full of longing and disappointment, though, this beauty is destroyed—literally stuffed and paralyzed—by the selfishly destructive actions of characters in love.
In short, this little play will change the way you view those gross flying creatures that swoop for sandwich remains at parks. Thanks, Chekhov.