Kidogo by Anik McGrory

From chapters.ca:
Kidogo is sure he's the tiniest creature on earth. All the other animals are so much bigger than he is. Kidogo sets out on a journey - through the woodlands, over the plains, down to the river - to see if he can find an animal smaller than he is. Is it possible that Kidogo is "exactly" the right size after all? Heartwarming illustrations and a gentle story will inspire and reassure young children who are just starting to find their own way in a big world.