A British import that I read about 15 years ago, similar to WATERSHIP DOWN, except that it was peopled (ok, bad choice of words) and narrated by birds, and one specific bird on a quest that involved a long distance flight. This wasn’t by any means a children’s book.
Could it possibly be Gay-Neck, the Story of a Pigeon by Dhan Gopal Mukerji?
https://en.wikipedia.org/wiki/Gay_Neck,_the_Story_of_a_Pigeon
Our 5th grade class read this and I remember the main bird would often go on long journeys.
Best,
Pitter Painter
Jonathan Livingston Seagull?
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Manka, the Sky Gipsy: The Story of a Wild Goose
Book by Denys Watkins-Pitchford