by: Wendy Jesse and Hannah Madden
The Lesser Antillean island of Saba (Caribbean Netherlands) harbors a unique anole species, Anolis sabanus, of which the males are easily distinguishable by their striking skin pattern. This endemic species is the only anole species found on the island, but is abundant within its native range of only 13 km2. Last April, a male individual was found outside of Saba on the neighboring island of St. Eustatius (Caribbean Netherlands) marking the first ever recorded exotic introduction of Anolis sabanus.
The exotic lizard was discovered next to shipping containers in the harbor of Oranjestad, St. Eustatius by a team of local and Dutch researchers: Tim van Wagensveld, Hannah Madden and Jasper Molleman. Because of its location, it is likely that the individual was a stowaway on one of the regular container shipments between Saba and St. Eustatius. An alternative theory is that the anole hitchhiked on a fishing boat, as local fishermen also travel regularly between islands. Other modes of introduction such as natural dispersal or pet release are highly unlikely: the Euclidean distance between the neighboring islands is approximately 25 km, and it is uncommon to keep these lizards as pets or for food (whereas for instance green iguanas are consumed on several Caribbean islands). Until now, no other Saban anoles have been found in this location or anywhere else on St. Eustatius, so the establishment of a reproductively successful exotic population in the near future is considered unlikely.
The individual was caught on site and is currently being kept in a freezer on the island. The animal was an adult male with a snout-vent length of 58 mm snout-vent length, which is relatively large for this species with a reported mean male SVL of 54 mm. A tail tip has been transported to Vrije Universiteit Amsterdam in the Netherlands for possible future genetic analysis.
St. Eustatius is a very unique island in the sense that for at least the last century, no exotic herpetofauna have established viable populations on the landmass. However, a few stray occurrences have been recorded, three of which happened over the course of the last three years. In 2013, a single juvenile green iguana (Iguana iguana) was discovered in the cargo shipment of a vessel that had traveled from Saba. The specimen was caught and destroyed. In February 2016, an adult female Iguana iguana was discovered in a residential area by a local resident, who alerted the local conservation organization STENAPA. The female was captured and destroyed. Based on feedback from regional experts, it is thought to originate from Central America, where the green iguana is farmed in large numbers for the pet trade. This is a commonly introduced species on islands such as St. Lucia, the Cayman Islands and St. Maarten, where the species has successfully established and spread. While nobody has come forward to admit this specimen was brought in as a pet, based on the area in which it was discovered, one theory is that it was smuggled in from St. Maarten as a juvenile and released as an adult, possibly due to its large size. Anolis sabanus is therefore the second non-native reptile species that is known to have recently reached the beautiful island of St. Eustatius. Unfortunately for these exotics, eagle-eyed local naturalists are on the lookout for any new arrivals!