Well... wouldn't they then be dragons?
How would you say that snakes cannot fly, as opposed to that they do not fly?
What is the infinitive form of the verb "fly" in this case? I got different translation options to both "fly" and "날".
The Journal of Zoology Studies reported that some snakes can fly from a tree to an other tree. Here you can see a picture: http://www.khatarnaknews.com/wonder-flying-snake-near-at-coimbatore-in-tamil-nadu/