Here is the full list of all 16 The Psychoduck achievements.
Kill the heron first time
Kill 10 herons
Kill 30 herons
Kill 50 herons
Collect 50 crowns
Hunt 10 snails
Hunt 30 snails
Hunt 50 snails
Push the stone for 200 meters
Push the stone for 500 meters
Push the stone for 1000 meters
Enter a bush
Take a ride on the alligator
Feed a turtle
Attract two frog to the bush