What does the dead seagull symbolize in the play The Seagull by Anton Chekhov?

In Act II, Konstantin enters with a gun in one hand and a dead
seagull in the other.  The seagull represents at least two large and significant symbols. In
addition to the symbols, the seagull has another function in that, though no gunshot is heard at
this moment in Act II, it represents foreshadowing of the final moments of the play when an
offstage gunshot actually is heard and Dorn announces in the play's final line: "You see,
Konstantin has shot himself."

Since Konstantin has laid the dead
bird at the feet of the young actress with whom he is in love, Nina, and said to her, "I shall
kill myself in the same way soon,"  it can be assumed that Konstantin sees himself as doomed.  He
believes that his art is not appreciated and that the woman he loves does not respect him as an
artist or love him as man.  The seagull, in this case, represents the vulnerability of Konstantin
to being "shot down" by critics of his work and the woman he
loves.

But the seagull is also a symbol for the young woman at whose
feet Konstantin lays it -- Nina.  In Act I, she herself has likened her carefree and happy life
on the lake to that of a seagull.  But, when Trigorn, an older, famous writer, enters the scene
in Act II, just after Konstantin exits, and sees the bird at Nina's feet, he
says:

Got an idea.  An
idea for a short story:  A young girl has lived in a house on the shore of a lake since her
childhood, a young girl like you; she loves the lake like a seagull, and she's as free and happy
as a seagull.  But a man comes along, sees her, and just for the fun of it, destroys her like
that seagull there.

And this is
exactly what Trigorin does to Nina.  When she returns in the final act of the play, hoping for a
glimpse of the man who has destroyed her, she confesses this to Konstantin.  So, both Nina and
Konstantin are connected to the symbol of the seagull.  They both attempt to fly free and attain
their dreams, and both are shot down and destroyed.

For more on
Nina, Konstantin and the seagull as symbol, please follow the links
below.