All of the creatures that have found lasting success on St. Martin have some kind of adaptation that makes them suited to life here. Freshwater species have more challenges than most, and the Apple Snail is well equipped to deal with them.

The Apple Snail is a large snail that lives in freshwater habitats. Members of their family live in Africa, Asia and the Americas, so scientists believe they date back to a time when all the continents were joined together. In this hemisphere, most species are native to South America, with a few found just in the Caribbean.

Many of the adaptations of the Apple Snail allow it to survive dry seasons, which happen each year in many tropical areas. Like many snails, they have an operculum—a door to their shell. They can seal it if the pond or stream they live in goes dry. They enter a state known as estivation, resting dormant until rains return.

The Apple Snail is also somewhat amphibious. They have a gill for breathing underwater, and a lung for breathing air. The ability to breathe air allows them to leave the water, at least temporarily, to feed. In stagnant water, they can use the lung to get additional oxygen from the air. They even have a special snorkel that they can extend to breathe air while they are still underwater.

Another benefit of their amphibious nature is the ability to protect their eggs. These snails leave the water, and lay a cluster of eggs above the water line. This protects the eggs from fish and other potential predators.

This variety of adaptations has made the Apple Snail quite successful. They have also made it an unwanted pest in places where it has been introduced accidentally or on purpose. One species—brought to Taiwan as a potential food—ended up seriously harming rice production. Its ability to leave the water to feed makes it a pest for other crops as well.

On St. Martin, this snail can be found in many of the small streams and drainage ditches in Concordia, often using its lung to traverse extremely shallow areas. Plants along the banks of these streams hold egg clusters, looking like pale, misshapen raspberries. The next time you are in the area, keep an eye out for these remarkable snails.

We are all familiar with the salmon’s journey. From the ocean, it enters rivers and makes a miraculous journey upstream to spawn and then die. In the Caribbean, there are many animals that find a life between the land and sea, and a home in fresh and salty waters.

On St. Martin, one is never far from the sea. Most obviously, we find it at the edge of every beach and at the bottom of each seaside cliff. But the sea also has ways of invading the island itself.

The sea seeps into the land through the porous limestone, adding its salty essence to well water. It washes upstream in the few spots where fresh water running down a gut reaches the sea. And, of course, salty water from the sea fills many of our salt ponds.

These brackish waters—neither part of the sea, nor totally separate from it—are a rich and unique habitat. The creatures that live here must adapt to the changing conditions of this zone: a rainstorm pushing the balance towards freshness, a dry spell pushing it to salty.

For some, life between two worlds is just a passing phase. Many juvenile fish use brackish mangrove wetlands as a nursery. In the shallow water, sheltered in mangrove roots, they find a safe place to grow. They then swim out to the coral reef to live. Some freshwater species—like the Mountain Mullet and many freshwater shrimp—float in the sea as eggs. After hatching they travel with the current, then swim into fresh water to mature.

Fish like the Crested Goby spend a lifetime on the borderline. They often live around mangroves, digging out a hollow in the sand or finding a root-sheltered hiding spot. They also live in estuaries where streams and rivers empty into the sea. Unlike most fish, they can live perfectly fresh water, pure seawater and anything in-between.

The Crested Goby is also flexible when it comes to food. Algae is on the menu, but so are crabs, insects, snails and even small fish. It is an integral part of the wetland community that captures nutrients washed down from the island. It plays a part in keeping the seas both clean and full of life.

The adaptable Crested Goby has found a niche that allows it to occupy the cracks and crevices between two worlds. In doing so, it has also turned its back on life in the open ocean. It is a creature of the sea, tied forever to the edge of the land.

They’re all around us, but we rarely notice them. They’re specially-equipped for climbing, but mostly live on the ground. They’re probably the most common reptiles on St. Martin, but few people even know their names.

St. Martin’s dwarf geckos are some of its most unique and mysterious residents. The island has two species. The smaller one is known as the Little Woodslave or Anguilla Bank Dwarf Gecko. The larger is called the Least Island Gecko or Leeward Banded Dwarf Gecko. Hidden in their confusing names are some clues to how unique they are.

The Little Woodslave is found on only a few islands in the world: Anguilla, St. Martin, St. Barts and the smaller islets in the immediate area. Combined, these islands make up the Anguilla Bank featured in the name Anguilla Bank Dwarf Gecko. When the last ice age lowered sea levels by locking water in glaciers, these islands were connected into a larger island. Hop over to Saba or Statia—which have never been connected to St. Martin—and you won’t find the Little Woodslave. Its cousin, the Saban Dwarf Gecko, lives there.

It’s hard to say what the name Least Island Gecko is supposed to mean. It doesn’t live on the fewest islands—it’s found from Anguilla down to Nevis. It also isn’t the smallest—there is a smaller dwarf gecko on every island where it lives. It’s other name, Leeward Banded Dwarf Gecko, isn’t much better. Sometimes they are banded, but other times not at all.

Dwarf geckos may be small, but they do have strength in numbers. There are over 100 species of dwarf gecko in the genus Sphaerodactylus, and the vast majority live only in the Caribbean. This vibrant diversity is one reason the Caribbean is considered a biodiversity hotspot.

In terms of population, one study measured dwarf gecko density equivalent to 21,000 geckos per acre. In theory that would work out to about 450 million dwarf geckos on St. Martin, if the entire island were perfect habitat for them. Probably there are far fewer, but the real number could be almost unimaginably high.

What do these tiny lizards do? They eat insects. Mostly ants and other very small things, and probably a lot of them. Perhaps enough to impact the whole ecosystem of the island. They turned their miniature size into an advantage that made them incredibly successful. In the Caribbean, their tiny feet leave a big footprint.

You can learn more about dwarf geckos and other animals found only in our region at Amuseum Naturalis, located at 96 Boulevard de Grand Case. The museum is free and open 4-8pm on Tuesdays and Thursdays. Get more info at http://amuseumnaturalis.com.

Animals have developed the power of flight several times. The insects were the first to take to the skies, and they became the most diverse group of animals in the world. Feathered dinosaurs grew wings and became birds, surviving when the rest died out. A third group used flight to colonize St. Martin while their fellow mammals could not.

Bats are St. Martin’s only native mammals. At least, they are the only ones alive today. Two prehistoric rodents lived on St. Martin, but they were long gone by the time recorded history began here. All other mammals on the island were brought by humans. This includes the wild ones—rat, mongoose, mongoose, raccoon, monkey—as well as our pets and farm animals.

Bats have used the power of flight to diversify, adopt many different lifestyles, and travel. There are over 1,000 species of bats in the world, and eight are found on St. Martin. Our bats pursue a variety of foods and make their homes in a variety of places.

The Velvety Free-tailed Bat eats insects and often lives beneath corrugated zinc roof sheets. It is a small bat, often seen in neighborhoods. It comes out around dusk to catch flying insects. To our benefit, mosquitos are often part of its dinner.

The Jamaican Fruit Bat and Antillean Cave Bat are larger, and they eat fruit. They are often seen around fruit trees at night, including almond, mango and palm trees. These bats nest in large groups in caves, especially the Grotte du Puits in the lowlands. The floor of the cave is covered in fruit pits brought back to the cave by the bats.

One of our most remarkable bats is the Fisherman Bat. This species uses echolocation to sense ripples made by fish on the surface of the water. Then it swoops down and grabs the fish with its large feet. Of course, all of this is done in complete darkness!

Bats have adapted to Caribbean islands, becoming new species along the way. The Antillean Cave Bat is found only in the Caribbean. The Lesser Antillean Tree Bat and Lesser Antillean Funnel-eared Bat are found only in the Lesser Antilles. The only mammals to fly, and our only native mammals, they have truly made the Caribbean their home.

You can learn more about St. Martin’s bats at Amuseum Naturalis, located at 96 Boulevard de Grand Case. The museum is free and open 4-8pm on Tuesdays and Thursdays. Get more info at http://amuseumnaturalis.com.

Evolution is happening all around us, but the processes that create new species are also being undone at the same time.

There are no bird species that live only on St. Martin. It’s not too surprising—on a clear day you can watch birds flying across to Anguilla or arriving here from Saba. Some birds even fly thousands of miles to live here each winter. But not all birds are such avid travelers.

Many of the birds on St. Martin are found only in our region. You can often tell by the names, like Lesser Antillean Bullfinch, Caribbean Elaenia, Antillean Crested Hummingbird, Carib Grackle and Green-throated Carib. Some other local birds have wider ranges, but distinct subspecies or varieties in the Caribbean. Although they can fly across the sea, they usually don’t.

Like all living things in nature, these birds are in the process of evolving. Over generations, Sugar Birds on St. Martin might adapt ever so slightly to the conditions on this island. They might get better at harvesting nectar from the flowers found here or nesting out of the reach of the mongoose. These could be the first invisible steps towards becoming a St. Martin Sugar Bird, found nowhere else in the world.

While this is happening, other events are reversing this evolution. A hurricane strike on a nearby island might send desperate birds here in search of food. As they integrate with the local Sugar Bird population they smooth out the tiny differences that were beginning to develop in the St. Martin population. The balance of isolation and movement can create regional varieties that never develop into distinct new species.

The ability to analyze genetic differences has given us a window into the subtle differences between Sugar Birds and a look into their past. A recent study compared over 40 different Sugar Birds from different areas with surprising results. Over the past several million years, there have been three separate periods when Sugar Birds from the Greater Antilles expanded into the Lesser Antilles. Each new wave mixed with the Sugar Birds here, and the birds living here today still carry the evidence of these movements in their genes.

You can learn more about the birds found only in our region at at Amuseum Naturalis, located at 96 Boulevard de Grand Case. The museum is free and open 4-8pm on Tuesdays and Thursdays. Get more info at http://amuseumnaturalis.com.

Giant can be a relative term. The Giant African Land Snail is definitely a giant among land snails, even if it is only a few inches long. It also manages to be one of the world’s worst invasive species, but it is it a giant problem on St. Martin?

What’s the big deal about this giant snail? Originally from Africa, it has been spread by humans throughout much of the world’s tropics. Once it becomes established, it can transform its new home in a variety of ways, endangering local ecosystems, agriculture and even human health.

The Giant African Land Snail is hermaphroditic, so every one is able to lay eggs. They do so 100-400 eggs at a time, up to 1200 eggs per year. Once they are introduced, they are quick to take over. Getting rid of them is hard. In Florida, an infestation was eradicated in the early 1970s. The effort involved killing 18,000 snails and cost over $4 million in today’s dollars.

These snails are known to eat over 500 different kinds of plants, including many agricultural crops. They eat leaves, fruits and roots, scraping away at them with 80,000 tiny teeth on their file-like radula. They can also transmit diseases to plants, including diseases impacting cocoa, tangerines and eggplants.

In some parts of the world, these snails are also responsible for spreading certain diseases, including some caused by nematode worms that live in the snails. Luckily, humans usually catch these diseases by eating raw or undercooked Giant African Land Snails, something that most of us will have no problem avoiding.

In the Caribbean, this snail was first found in Guadeloupe in 1984. By some accounts, it arrived in St. Martin along with supplies imported when the island was rebuilding after hurricane Luis. Whether that’s true or not, Guadeloupe does seem like a likely source for our snails. Today, these snails can be found all over the island.

Since St. Martin’s major industry is tourism, this snail probably has a bigger impact on local ecology than it does on the local economy. It may harm native plants and outcompete local snails. Like many other invasive species, understanding the extent of its impact would require extensive research that has not yet been done here. On St. Martin, it may not be the giant problem it is in some places.

You can learn more about invasive species and their impact on St. Martin at Amuseum Naturalis, located at 96 Boulevard de Grand Case. The museum is free and open 4-8pm on Tuesdays and Thursdays. Get more info at http://amuseumnaturalis.com.

One of the challenges of studying the ecology of an island is uncertainty about past events. Be it twenty years, two hundred years, or two million years ago, it is impossible to go back in time to witness the first arrival of a plant or animal species. Instead, our understanding is informed by whatever historical and biological data is available.

When it comes to the Red-footed Tortoise in the Lesser Antilles, there are a few possibilities. It could have arrived on its own, floating on a raft of vegetation to each island. It could have been brought by Amerindians from South America and introduced to the islands they visited. It even could have been introduced during the colonial era or the modern era.

On St. Martin, we can probably rule out the last possibility. In 1658, Charles de Rochefort published an account of his time in the Caribbean which mentioned the presence of tortoises in the forest on St. Martin. Only settled in the 1620s, it seems likely that tortoises were living on the island before it was colonized by Europeans.

Was the Red-footed Tortoise brought to these islands by Amerindian people? Many believe this is the most likely scenario. The Arawak and Carib people migrated from northern South America—where the Red-footed Tortoise is a native species—to the Lesser Antilles. It would have been very practical to bring the tortoises with them and release them, creating a renewable food supply.

There are also reasons to believe the tortoise did not arrive on its own. Most of the reptiles that colonized the Lesser Antilles by their own means diverged into different species on each island or group of islands. The Red-footed Tortoise seems essentially the same throughout the Caribbean. This suggests it arrived recently.

Also, we know what can happen when tortoises on islands: they become giants, like the tortoises of the Seychelles and Galápagos. It would be reasonable to guess that tortoises colonizing Caribbean islands millions of years ago would have ample time to become giants.

As it turns out, we don’t need to guess that giant tortoises could exist in the Caribbean. About 40 miles from St. Martin, Sombrero Island was once home to the Sombrero Giant Tortoise. Remains of this tortoise were found in guano extracted from the island. Several other extinct species of giant tortoise are known from other parts of the Caribbean. It is possible that existing populations of giant tortoises were hunted to extinction by the earliest humans who arrived here and then replaced by the tortoises we see here today.

You can learn more about the Red-footed Tortoise and other species introduced to St. Martin at Amuseum Naturalis, located at 96 Boulevard de Grand Case. The museum is free and open 4-8pm on Tuesdays and Thursdays. Get more info at http://amuseumnaturalis.com.

Love is always in the air on steamy Caribbean nights, and you can hear the songs that prove it. A gentle hum, a sawing drone, or a piercing chirp, these calls broadcast into the darkness, pleading for partnership.

A nocturnal lifestyle has certain advantages here on St. Martin, especially if you are very small. Birds and lizards are dangerous predators to the insects and tiny frogs living on the island. One way to escape their prying eyes and hungry mouths is to hide during the day. Many of the nocturnal critters on St. Martin do just that. Johnstone’s Whistling Frog often waits out the daylight in the dampness beneath stones or under dead leaves. Many crickets and katydids hide in plain sight, camouflaged to look like the plants they live on.

Conducting all of one’s business at night does pose certain difficulties when it comes to the business of love. When predators can’t see you, neither can your prospective mate. Although there are numerous ways to find a partner in the dark, sound is one of the most common methods.

In most cases, the males do the calling. There is a fairly simple reason for this. Producing eggs requires more effort than producing sperm, so female frogs and insects are selective about who will get to fertilize them. Males are the ones that need to prove their worth, so they do the calling. The calls they make advertise both their location and their fitness.

A nighttime stroll in garden, field or forest will be filled with song. The Snowy Cricket—a tiny, delicate insect—rubs its transparent wings together to produce an airy buzz. The song from a single cricket is slight, but in a field of Bellyache Bush the chorus of hundreds can be enveloping.

The Money Bug prefers to call from tall grasses. It has a file on one forewing and and a scraper on the other. Its song is determined by the shape of these sound-making features and how it plays them. It chooses loud and grating, in a near-continuous drone broken by occasional momentary silences.

The island’s most famous nighttime singer is Johnstone’s Whistling Frog. This tiny frog fills up a huge air sac in its throat to create its trademark whistle. It is surprisingly loud, and many sleepless people have discovered how hard it is to find its source. A chorus of whistling frogs on a rainy night may be the most identifiable sound of Caribbean.

You can learn more about St. Martin’s nocturnal creatures—and listen to the sounds they make—at Amuseum Naturalis, located at 96 Boulevard de Grand Case. The museum is free and open 4-8pm on Tuesdays and Thursdays. Get more info at http://amuseumnaturalis.com.