Tsubasa Reservoir Chronicle the Movie: The Princess in the Birdcage Kingdom (Japanese: 劇場版 ツバサ・クロニクル 鳥カゴの国の姫君, Hepburn: Gekijōban Tsubasa Kuronikuru: Torikago no Kuni no Himegimi) is a 2005 Japanese animated action fantasy short film based on the Tsubasa: Reservoir Chronicle manga written and illustrated by manga artist group CLAMP. The short film was directed by Itsuro Kawasaki, co-written by Junichi Fujisaku and Midori Goto, and was produced by Production I.G. The film premiered in Japanese theaters on August 20, 2005 in conjunction with xxxHolic: A Midsummer Night's Dream, another Production I.G animated film and based on CLAMP manga. Set between the two seasons of the anime series Tsubasa by Bee Train, the film continues Syaoran's group's journey to find Sakura's "feathers" (memories) in different worlds. On the journey they arrive at the Country of Birdcages, which contains one of Sakura's feathers.

The Tsubasa and xxxHolic films were conceived by Kodansha, the Japanese publisher of both manga. After convincing Production I.G to develop them, Kodansha director hired Junichi Fujisaku to write the Tsubasa film. Like the TV series, Yuki Kajiura was the score's composer and the producer was Tetsuya Nakatake. In North America The Princess in the Birdcage Kingdom was licensed by Funimation Entertainment, who released it with A Midsummer Night's Dream and episodes of the Tsubasa anime.

The film received a mixed response from manga and anime publications and other media; although its animation and pacing were praised, its length was criticized as only ten minutes longer than the TV episodes.