Thank you for commenting !
Maybe it is not obvious, but herons react to sound. On croak and on water splashes, when a frog misses a lilypad. And when a frog misses a lilypad, it swims to the nearest one. While it swim, you cannot jump. Hence the delay. It is possible to never attract herons at all if you jump precisely) Difficulty of the games, how I see it, lies in the player panicking and missing jumps. It was intentional, but I don't want it to be so hard for players.
I hope your experience wasn't frustrating (