Like many infertile women throughout history, hapless Duck suffers from social stigmatization and low self-esteem. Even though the obvious solution, adoption, is emotionally satisfying to her, she continues to suffer the mockery and criticism of her peers, who deride the physical dissimilarities between Duck and her unhatched egg. Although hurt by their treatment, Duck offers the egg unshaken love, doing her best to provide physical and emotional protection.
I would have preferred had the eggs been depicted in a more accurate way. Neither crocodile eggs nor baby crocs are huge -- a real baby crocodile would be just as small as a duckling! The illustrations were good, but not as strong as in some of Gravett's other books. If you haven't read her before, I would recommend Little Mouse's Big Book of Fears as a better starting point.