The Night Shift: What Happens in a Marsh After Dark

Most people visit the marsh during the day. They walk the boardwalk, scan the water for herons and egrets, and maybe spot a fiddler crab waving its claw. But the marsh at night is a different world. The light changes, the temperature drops, and the animals that were hiding during the day emerge. The night shift is on.

If you stand at the edge of a salt marsh after dark, you will hear it before you see it. The sound is a chorus — a layered, rhythmic pulse of chirps, trills, and buzzes. The dominant voices are usually insects: katydids, crickets, and the occasional cicada. But there are other sounds too. The splash of a fish. The rustle of something moving through the grass. The distant call of a night heron.

Who Comes Out After Sunset

Many marsh animals are nocturnal or crepuscular, meaning they are most active at dawn and dusk. The reasons vary. Some are avoiding the heat of the day. Some are avoiding predators. Some are following their food.

Raccoons are common marsh visitors at night. They wade through the shallows, feeling for crabs and mussels with their sensitive paws. Mink and river otters patrol the creeks, hunting fish and crustaceans. Marsh rabbits — smaller and more secretive than their upland cousins — emerge to graze on grasses and sedges. And then there are the birds. Black-crowned night herons and yellow-crowned night herons are stocky, short-necked birds that spend the day hidden in trees and come out at dusk to hunt. Clapper rails, which are secretive at the best of times, are more likely to be seen at night as they probe the mud for snails and crabs.

The water itself is alive after dark. Small fish that hide in the grass during the day move into open water to feed. Shrimp and crabs become more active. Bioluminescent organisms — tiny plankton that produce light when disturbed — can turn the water into a field of blue sparks if you drag your hand through it.

The Sensory World of the Night Marsh

Without light, the marsh is a place of sound and smell. The smell is stronger at night, especially at low tide, when the mud is exposed and the bacteria that break down organic matter release sulfur compounds. It is a smell that some people find unpleasant and others find strangely comforting — the smell of a working ecosystem.

The sounds are more than just background noise. They are a form of communication. Male frogs call to attract mates. Crickets and katydids sing to establish territory. The calls of night herons and rails carry across the water. If you learn to recognize the voices, you can identify many of the animals without ever seeing them.

Night is also a time of increased risk. Predators are active, and prey animals must be vigilant. The marsh is not a peaceful place after dark. It is a place of hunting and being hunted, of calling and listening, of movement in the dark. It is the same ecosystem as the daytime marsh, but the rules have changed.

I think the night marsh is worth visiting, even if it makes you a little uneasy. It reminds us that the natural world does not stop when we go to bed. It keeps going, on its own schedule, with its own cast of characters. All we have to do is show up and listen.