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How to find new species for St. Eustatius

Posted on 26-10-2015 by Employees of the Dutch Mammal Society: Sil Westra, Wesley Overman, Ellen van Norren 13 october 2015

Many introduced or domestic mammals live on the island of St. Eustatius (Statia): black rats, goats, cats, dogs, cows, chickens and pigs. Very little indiginous species are present or remain.

On the island once lived the Nevis rice rat, but historically there are no endemic monkeys, mice or other small mammals present. In a way it is logical, because the island is very small and far away from the main land, and the island was once created by volcanoes in the ocean: it is difficult or impossible to reach. The mammals that did manage reach the island are bats and marine mammals.

If you are a bat on Statia, your first problem is to get drinking water. There is very little fresh open water, so when you wake up at 18pm, your first concern is to get to a swimming pool. There we were, catching bats with mistnets. Most bats we caught were small insect-eating bats molussus molussus. Because they have a long tail they very much look like flying shrews. We also caught some bigger fruit-eating bats and glued a tiny transmitter on their back. With a radio receiver we van track these fruitbats to find their roostsites during the day. 

The bats that we caught were measured (fore arm and head-body), and weighed. We also determined the sexe, and whether it was an adult or juvenile. After that, DNA was taken, photos were taken and they were examined on parasites. Especially, we were keen on recording the sounds that the bats produce to communicate and for echo-location. 

After some short hours of sleep we woke up early to avoid the heat and hiked to all the remote edges of the island to set up camera traps. Of course we hoped to take photos of the extinct Nevis rice rat, or an unknown species of dormouse, or any other unknown mammal. But all we got so far were hermit crabs, more hermit crabs, dogs, cats, goats and lizards. And a couple times we lucky enough to take a photo of a black rat. The camera traps are triggered by heat and motion and some we additionally put on time lapse mode. So we had photos taken of very 5 minutes for a week for some plots. Very interesting to see what comes along, but apart from the cattle and rats, no mammals.