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.
Anolis sabanus (Saban anole). Source: The Reptile Database.
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.
Map of Saba and St. Eustatius with probable point of introduction for A. sabanus.
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.
Specimen of exotic A. sabanus male. Photo credit: Hannah Madden.
Specimen of exotic A. sabanus male. Photo credit: Hannah Madden.
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!
- Spot the Differences: Native vs. Exotic Anoles - November 8, 2016
- First Ever Recorded Introduction of Endemic Saban Anole (Anolis sabanus) - June 2, 2016
- Do Communities of Introduced Anoles Differ from Natural Communities? - June 16, 2014
Peter Uetz
Just to clarify the source of the first photo: it’s originally from the Dutch Caribbean Nature Alliance, http://www.dcnanature.org/saban-anole/. Unfortunately we don’t have an author name.
Wendy Jesse
Thanks! Unfortunately, I cannot edit the text anymore now it’s been published. But I’ll use the DCNA as reference in the future!
bolko
Isn’t an introduction to a neighbouring island, where most probably there is a species close enough for hybridization to occure, stretching the definition of an exotic introduction?
Bob Powell
Not necessarily, especially if the neighboring islands are on different banks and have never been connected in the past. For example, Saba (a volcanic peak near the Saba Bank) has an endemic population of Iguana iguana, whereas the St. Kitts Bank (of which St. Eustatius is a part) has endemic I. delicatissima. So, what’s on each island is essentially what ancestors of the modern taxa happened to make landfall on that particular speck in the ocean. Only in recent years, with humans entering the scene, have introductions to neighboring (and more distant islands) become relatively commonplace. What’s interesting in this instance (the Saba Anole on Statia) is that most inter-island relocations in the region emanate from St. Maarten, which is a major commercial center and the source of most exotics in the region (including non-native Green Iguanas that apparently have filled the niche vacated by extirpated I. delicatissima).