Here is the full list of all 20 Rapid Squirrel achievements.
Land 3 times
Land 5 times
Land 10 times
Land 15 times
Land 20 times
Land 35 times
10 kilometers of flight
20 kilometers of flight
50 kilometers of flight
One level passed
Three levels passed
Five levels passed
Seven levels passed
5 nuts collected
25 nuts collected
50 nuts collected
85 nuts collected
100 nuts collected
120 nuts collected
150 nuts collected