Great blue herons are skilled hunters, standing stock-still or wading very slowly through water until unsuspecting prey swims by. Then WHAM! They strike.
While fish are the most common prey, great blue herons will also stand in fields and hunt mice or voles. They are the largest heron in North America, standing around 36–54 inches tall. So you can just imagine the size of fish (or rodent) they are able to toss back. Sometimes they are a little overly ambitious, and they've been known to choke on prey that is too large to swallow.