Last Sunday, as I watched the Night Herons at the Ocean City Welcome Center, I kept hearing loud noises as if someone was breaking branches. It turned out that it was the herons themselves. As you can see from the photo below, these herons have very sturdy, thick bills.
In fact, they are known as crab eaters, eating whole crabs by crushing them with their bills before swallowing them. With larger crabs, they grab them with their bill and then shake them violently to break them up into smaller pieces. Their bills are like those steel crab crackers that they have at restaurants that serve crabs.
A the start of breeding season, the herons have to build nests where the females will lay their eggs. They go around their neighborhood and use their bills to break dead branches and bring the pieces back to their nests.