In checking my facts with that irrefutable source – Wikipedia – herons eat a number of aquatic creatures – fish, reptiles, amphibians, crustaceans, molluscs, aquatic insects. I don’t know why I felt the need to bother as most of my poems are nonsense.
Have you wondered why a bird that dives for fish for a living has feathers that get waterlogged so it can’t fly? It doesn’t make any sense or does it? A cormorant’s lack of preening oil – which makes water run off a duck’s back – makes them speedy underwater and better at fishing.