Beach dunes are the most iconic part of Bermuda, making up our sandy beaches and providing the corridor into our beautiful blue waters. They are always thriving with tourist activity, as well as biological and geological activity.
Where To Go
Sand dunes are present on all of Bermuda’s sandy beaches. However, true sand dune habitats can only be observed at beaches undisturbed by human influence. Most tourist beaches are raked, destroying much of the environment of the high tide line. Instead, visit secluded beaches such as Cooper’s Island, or Nonsuch’s South Shore.
If you can’t find an undisturbed beach, you can still see much of the sand dune habitat, however. The back half of the sand dune habitat can be observed at various South Shore beaches, like Horseshoe Bay. Here, the beach dunes slope up and are inhabited by a variety of plants and animals.
What To Bring
- Camera – make sure you bring a camera to document your expedition
- Journal – it can be useful to keep a journal to record your observations
- Small container and microscope – many of the animals you will find on sandy shores are too small to be seen by the naked eye. You can be rewarded with the sight of protozoans, flatworms, roundworms, tiny crustaceans, and water bears with a normal compound light microscope. If you can’t bring an optical or compound light microscope with you, consider bringing some sand samples back home to have a closer look at. Make sure you return the sand and the animals later, though.
How Are Sand Dunes Formed?
Sand dunes were very important in the formation of Bermuda. Early on in Bermuda’s history, when we were just a plinth of rock sticking out of the ocean, it was sediment from sand dunes that blew in to give us a real landmass.
Sand dunes are created with sediment and wind. For many years Bermuda was a shifting landscape of sand dunes, 10 times larger than the island’s size today. No vegetation grew on these sand dunes, which would have held them together. As the top layer of the sand dried, it could be blown inshore by winds, creating mobile sand dunes continually forced downwind.
In Bermuda’s more recent history, some of the South Shore mobile sand dunes engulfed houses and roads as the wind blew them. However, Bermuda’s present-day landscape means such mobile dunes can only be created with hurricane-force winds, and these quickly become vegetated and stationary after the winds subside. Don’t worry, your house won’t suddenly be swallowed up by sand like those in cooler climates are sometimes swallowed up by snow!
Sand dunes are what make up our famous beaches. Many commercial beaches are raked, eliminating the first low sand dune that forms on the shore, called an embryo dune. As the beach rises, the dunes become higher and more vegetated, eventually leveling out and supporting a dense foliage cover.
The sandy shore is a poor place for animals to live because of its instability. Winds and waves buffet the shore, sometimes removing huge amounts of sand, making it a dangerous place to live. Indeed, in Bermuda’s early years, when all we were was a collection of sand dunes, it was thought that many would-be native animals were killed in the unstable early habitat, a Bermudian land tortoise being one of them. The specimen we found of the tortoise was hiding in its shell, as if suddenly engulfed by a sand dune.
What You Might See
Not many animals live on the sandy shore, but the few that do are highly adapted to life here. Most are very small, or have hard shells and are capable of burrowing rapidly into the sand, to avoid predation or to shelter from drying out.
Many of the animals you will find on sandy shores are very small, some too small to be seen by the naked eye. You can see protozoans, flatworms, roundworms, tiny crustaceans, and water bears with a normal compound light microscope. These animals live among sand grains.
There are plenty of worms and little insects that are abundant in the high tide line, feeding in the dead seaweed there. These include ants, devil’s coach horse, tiger beetle, seaside earwig, and beach flea.
The most obvious animals you may see are crustaceans, including the ghost crab, the red land crab, the mole crab, and the mottled swimming crab.
Finally, the skink sometimes visits the sandy shore in order to feed, and birds do as well, including the kiskadee, ruddy turnstone, and sanderling.
For more information on Sand Dunes and for help with identification, check out Sandy Coasts by Martin L.H. Thomas.