Here is the full list of all 18 Crazy Flying Squirrel achievements.
Fly 1000m
Fly 2000m
Fly 5000m
Landing 3 times
Landing 5 times
Landing 10 times
Landing 15 times
Landing 20 times
Landing 35 times
Complete Level 1
Complete Level 3
Complete Level 5
Complete Level 7
Сollect 5 nuts
Сollect 25 nuts
Сollect 50 nuts
Сollect 100 nuts
Сollect 150 nuts