Merrie Melodies is an American animated series of comedy short films produced by Warner Bros. from 1931 to 1969, during the golden age of American animation. As with its sister series, Looney Tunes, it featured cartoon characters such as Bugs Bunny, Daffy Duck, Porky Pig and Elmer Fudd. Between 1934 and 1943, the Merrie Melodies series were distinguished from the black-and-white, Buddy or Porky Pig-starring Looney Tunes shorts by an emphasis on one-shot stories in color featuring Warner Bros.-owned musical selections. After Bugs Bunny became the breakout recurring star of Merrie Melodies and Looney Tunes went to color in the early 1940s, the two series gradually lost their distinctions and shorts were assigned to each series more randomly. Merrie Melodies was originally produced by Harman-Ising Pictures from 1931 to 1933, and then Leon Schlesinger Productions from 1933 to 1944. Schlesinger sold his studio to Warner Bros. in 1944, and the newly renamed Warner Bros. Cartoons continued production until 1963. It was outsourced to DePatie–Freleng Enterprises and Format Productions from 1964 to 1967, and Warner Bros.-Seven Arts Animation resumed production for its final two years. Three of the Merrie Melodies films (Tweetie Pie, Speedy Gonzales and Birds Anonymous) won the Academy Award for Best Animated Short Film and another three (Duck Amuck, One Froggy Evening and What's Opera, Doc?) have been inducted into the National Film Registry of the Library of Congress. In 2013, TV Guide ranked the Warner Bros. Cartoons (ranked as Looney Tunes) the third Greatest Cartoon of All Time (out of 60), one of only three film series to make the list (the other two being the Pink Panther series and Tom and Jerry).