The book is called South by Patrick McDonnell. It's about a little bird, who falls asleep under a tree. He doesn't notice when his friends and family head off to begin their flight south. He wakes up, panics, and asks a cat for help. The pictures illustrate the friendship between the two, as the cat takes the little bird on a journey to find his friends. Charmingly simple and old fashioned. I'm completely in love.
I'll resist the urge to post the book in its entirety.