Birney began her writing career in advertising, for Disneyland, and then scripting trailers and commercials for Walt Disney Pictures releases. When the Disney Channel launched, she wrote for Welcome to Pooh Corner and Dumbo's Circus. She also wrote for Zoobilee Zoo, The Puzzle Place, and various ABC and CBS live-action afterschool specials. Animation credits included Snorks, Doug, Maxie's World, Bobby's World, Camp Candy, Adventures from the Book of Virtues, and Madeline.