Tweeter is the Jetsons' robotic pet bird.
Being a small, mechanical bird, Tweeter doesn't have any feathers but rather a gray chrome of which he's comprised. But has also has wings held in place by bolts or screws, light blue eyes, a red neck, an antenna on his head with two rings, an oval in his front outlining his chest and belly, an orange beak and feet, and a pointy tail.
Tweeter is seen early on, when another dawn arrives. Rosey removes the cover from his cage and bids him a good morning. Tweeter then starts coughing, due to the smog coming from outside their apartment and the apartment being low where the pollutant is. To escape the air pollution, Rosey pulls a lever that raises the sky apartment higher and other buildings are also raised. It's never explained nor revealed when the Jetsons got Tweeter and he isn't seen again throughout the rest of the movie.