What's that animated film?

What is that movie where a bird (Pidgin?) gets caught in an oil spill (If I remember the beginnings correctly) and flies into a backyard where a cat attempts to save her, but can't. But before she dies she lays her egg and the cat takes care of it. He helps the young bird (Pidgin) to grow until she is old enough to migrate and finally in the end of the movie flies off?