Doraemon: Nobita to Tsubasa no Yuusha-tachi

Nobita and his friends learn about missing bird flocks and speculate they were taken by winged beings. Inspired, Nobita builds mechanical wings and discovers a real winged creature named Gusuke emerging from a time-space distortion. After assisting Gusuke, Nobita and his friends are pulled into the distortion and arrive in Birdpia, the world of winged creatures.