that is a lot more time than I've spent playing... though my high score is 143.
Some advice for anyone having trouble:
-You can transform back to human using SPACE.
-There is a minimum of three enemy birds between two coins and the more birds went by since the last coin, the more probable it is to get a coin.
-Jump very quick and late, to get over the cacti, even if a bird is directly above it.
-Transform back to human after collecting a coin, to prevent using up too much of your "bird-time"