Klingon: Because it did not have the courage to face us in honorable battle!

Romulan: Clearly, the chicken is up to something.

Ferengi: Because someone forgot to put up fencing to direct it to the toll crossing, which I will be happy to erect in exchange for a 50% share of the tolls collected from it.

Lantean: The sole purpose of a chicken is to one day cross the road.

Jeanette Isabelle
"I have no quarrel with you, good sir knight, but I must cross this bridge." Arthur, Monty Python and the Holy Grail