This is skellig, from David Almonds book of the same name! As the story goes, two kids find him in an old brokendown shed at the end of one of their gardens. At first they think its a dead man, but he's alive, worn and fragile with Mr Arthur-Itis, skellig has no will to live, untill the children move him to a safer place in the loft of an abandoned house. When they move him they discover two hard lumps beneath his coat, they pull his jacket of revealing his broken, torn wings. The loft is occupied by a family of flegling barn owls, with their help and the love of the children, skellig grows stronger, and eventually flys away.