In the Inner Harbor: Northern Water Snakes

Fear of snakes—or ophidiophobia—is one of the most common phobias. People seem hardwired to be afraid of snakes. In many cases, though, the fear is unfounded. Most nonvenomous snakes are harmless to humans, and all snakes play an important role in maintaining balanced, healthy ecosystems.

About Northern Water Snakes

Northern water snakes are a nonvenomous, beneficial species found in every county in Maryland. True to their name, water snakes are at home in a variety of brackish and freshwater habitats. They live in streams, ponds and rivers in the mountains of Western Maryland and in tidal marshes and tributaries of the Chesapeake Bay, including the Inner Harbor in downtown Baltimore.

It's not uncommon to see a Northern water snake swimming in their graceful, undulating way along the shoreline of a Chesapeake Bay tributary. Here in Baltimore City, these snakes swim at the surface of the Inner Harbor or bask along its edges. If you're lucky, you might spot a Northern water snake when visiting Harbor Wetland here at the Aquarium or the wetlands at Fort McHenry or Masonville Cove in South Baltimore.

Northern water snakes emerge from hibernation in April and are typically active during the day and at night until late October. When temperatures drop, these snakes leave the water to hibernate underground in decaying tree stumps, mammal burrows or hillside rock crevices.

A Dangerous Doppelganger

Northern water snakes are often victims of misplaced fear because they resemble venomous water moccasins, also known as cottonmouths. Even though Northern water snakes are completely harmless, they are sometimes mistaken for this venomous species and killed.

In addition to the fact that Northern water snakes and water moccasins are found in and around bodies of water, both species have similar dark coloring with muted stripes and are about the same size. Some states are home to both species, but Maryland is not one of them. Water moccasins live in the southeast United States; there are no known populations north of southern Virginia. There are only two venomous snake species in Maryland, the Northern copperhead and timber rattlesnake, and it would be extremely rare to find either of these swimming in water.

Northern water snakes do reap evolutionary benefits by looking like a more dangerous species, though. It's common for a nonvenomous species to mimic the coloration or behavior of a venomous species to trick potential predators. One common misconception is that any snake with a triangle-shaped head is venomous. This often results in the unnecessary killing of harmless snakes. All snakes, even venomous ones, are an important part of the ecosystem and food web.

Through Harbor Wetland and other work on our campus, and through our partnerships at Fort McHenry, Masonville Cove and elsewhere, the Aquarium is one of many organizations making sure the Inner Harbor and other urban waterways are healthy, viable habitats for species like Northern water snakes.