Inspired by the Hemulen, who has temporarily left plants aside for a study of birds, Moomin and his friends go out to study Nature, armed with a book on the subject, and find a lot of things they haven't even noticed before. They also find a bird's nest high on a cliff, the mother bird being attacked by a kite. Both mother and fledglings are taken to Moominhouse, and while the mother is patched up the big problem arises - how to get her babies to eat ? They won't take a thing from foreign hands...