Swift Shifter

You can use your Wild Shape or shapeshifting ability on your turn as a bonus action, rather than as an action. (If you can already use a bonus action, this feature has no effect.) Also, when you are imperiled, the forces of nature within you can allow you to change in a blink. When you fall more than 30 feet, or immediately after you take damage or fail a saving throw,  you can use your reaction to use your Wild Shape or shapeshifting ability. 

Flying Creatures & Falling

"If you'd like a flying creature to have a better chance of surviving a fall than a non-flying creature does, use this rule: subtract the creature’s current flying speed from the distance it fell before calculating falling damage. This rule is helpful to a flier that is knocked prone but is still conscious and has a current flying speed that is greater than 0 feet. The rule is designed to simulate the creature flapping its wings furiously or taking similar measures to slow the velocity of its fall." (Xanathar's Guide to Everything, chapter 2)