Here is the full list of all 48 Where the Wild Things Are achievements worth 1,000 gamerscore.
Collect all Skulls
Collect all Turtles
Find 95 Stars
Collect all Honeycombs
Collect all Owl Eggs
Collect all Seeds
Collect all Houses
Collect all Geodes
Complete a ride with Carol without crashing
Complete a Sailing mission without crashing
Complete the game on Hard
Complete the game on Normal or higher
Complete the game on Easy or higher
Complete 'A Trip to the Moon'
Earn 10 Hearts
Complete 'Below the Roots'
Collect 25 Turtles
Complete 'Setting Sail'
Find 65 Stars
Complete 'Old Willow'
Collect 25 Owl Eggs
Cause three different Wild Things to sneeze
Complete 'Crumbling Island'
Complete 'Rebellion'
Collect 25 Honeycombs
Defeat five enemies with one firefly bomb
Earn 7 Hearts
Defeat 100 Shadow Creatures
Complete 'Seasick'
Defeat 25 Lightning Bugs
Allow three different Wild Things to fade into oblivion
Find 40 Stars
Collect 25 Geodes
Complete 'Canyon River'
Defeat 250 Fireflies
Complete 'The Cave'
Collect 25 Seeds
Be eaten by three different Wild Things
Start a Dirt Clod Fight with multiple Wild Things
Complete 'Road to Nowhere'
Find 20 Stars
Collect 25 Houses
Earn 4 Hearts
Complete 'Arrival'
Find 5 Stars
Power-swing from three bars
Collect 25 Skulls
Defeat 15 enemies in a row in melee without being hit