Your child loves every creature, no exceptions. It starts with a bull who would rather smell flowers and ends with a fox in wartime — growing up one step at a time, exactly as fast as your child does.
What climbs on this trail is emotional weight — these books ask more of the heart long before they ask more of the reading. The first three are warm and safe. The fourth brings the most famous goodbye in children's books, in the gentlest hands there are. The last two trust your child with real grief, and then with war. An animal-loving child will follow the animals anywhere; this order just makes sure each 'anywhere' arrives when they're ready for it.