Get an inside look at science as it happens in the Caribbean. This week we don’t find a gecko on St. Kitts and Nevis.

There’s no eureka moment when you go into the wild and don’t find something. No lightbulb flashes on. It’s more like mood lighting. Each time you don’t see it, an idea in the back of your mind gets a tiny bit brighter. It starts to feel odd that you haven’t seen it yet. Eventually, you realize you may not see it at all.

In general, we know which lizards should be on each island. There aren’t very many. St. Kitts and Nevis each had less than ten native species. We can use geography to predict what lizards should be on each island. In particular, we know that St. Kitts, Nevis and Statia were connected into one island about 10,000 years ago. So, they probably had the same lizards.

In the nature, 10,000 years is not a long time. Still, things have happened since then. Sometimes animals disappear from islands. The Lesser Antillean Iguana was massacred by the mongoose on St. Kitts and Nevis. On mongoose-free Statia it still survives.

The Least Island Gecko is another lizard that seems like it should be on St. Kitts and Nevis. It is a tiny gecko that is found on islands from Anguilla to Statia. Unlike the Lesser Antillean Iguana, dwarf geckos often coexist with mongoose. In fact, the closely-related Saban Dwarf Gecko is doing fine on St. Kitts and Nevis.

We searched all the places the Least Island Gecko goes. We looked under logs on the forest floor and in the loose bark of the tamarind tree. We looked for it at night. We looked for it in insect traps that sometimes catch these tiny lizards. We didn’t find it.

What does it mean when we don’t find an animal? It is hard to say. For starters, we can’t really say it isn’t there at all. Maybe we just failed to find it. We can say that it is at least very rare. We don’t know why we didn’t find it, but we do know there must be a reason.

St. Kitts and Nevis are not tiny islands. They include plenty of space for a tiny lizard, even when sugarcane covered much of the islands. It probably wasn’t wiped out by a single big event, like a hurricane. The infamous monkeys? No one thinks the monkeys ate them all.

Nature is complex. Everything is connected, but there’s rarely a straight line from cause to effect. Maybe there isn’t one reason why the gecko is missing. And maybe the missing gecko is just a clue to a bigger change in life on these islands.