Abel's island / William Steig.

Enhanced descriptions from Syndetics:

William's Steig's Abel's Island tells the story of a mouse who gets swept away from his beloved wife -- a truly timeless classic about life's simple pleasures.

Abel's place in his familiar, mouse world has always been secure; he had an allowance from his mother, a comfortable home, and a lovely wife, Amanda. But one stormy August day, furious flood water carry him off and dump him on an uninhabited island. Despite his determination and stubborn resourcefulness--he tried crossing the river with boats and ropes and even on stepping-stones--Abel can't find a way to get back home.

Days, then weeks and months, pass. Slowly, his soft habits disappear as he forages for food, fashions a warm nest in a hollow log, models clay statues of his family for company, and continues to brood on the problem of how to get across the river--and home.

Abel's time on the island brings him a new understanding of the world he's separated from. Faced with the daily adventure of survival in his solitary, somewhat hostile domain, he is moved to reexamine the easy way of life he had always accepted and discovers skills and talents in himself that hold promise of a more meaningful life, if and when he should finally return to Mossville and his dear Amanda again.

Abel's Island is a 1976 New York Times Book Review Notable Children's Book of the Year and Outstanding Book of the Year, and a 1977 Newbery Honor Book. It was adapted to a short animated film directed by Michael Sporn in 1988.