In the movie, Sparky is a fly who works with Jake the kangaroo mouse at the Australia Airport. He is first seen playing checkers with Jake to which he wins and Jake calls him a "wise fly." Then they get a call over the radio from Wilbur the albatross requesting permission to land to which Jake tells Wilbur not to because the runway isn't big enough for a bird his size, but Wilbur won't listen and decides to land to which Jake tells Sparky they have to extend the runway and need to make a drag line. After Wilbur lands Jake gets a ramp for Bernard and Bianca to get off Wilbur and when he sees Miss Bianca he becomes smitten by her to which Sparky lets out a buzz knowing what's happened to Jake. Then Wilbur realizes that he has a back pain from landing and Jake orders Sparky to watch the tower while he, Bianca and Bernard get Wilbur to the hospital.
Sparky isn't seen after this for the rest of the film, so it is assumed that he is still watching the tower and waiting for Jake to return from helping Bernard and Bianca.