Lesser Antillean Iguana (Iguana delicatissima)

Mohamed bin Zayed Species project number 172517158

Preventing the loss of one of the last populations of Iguana delicatissima

This project is a collaboration between Reptile Amphibian Fish Research Netherlands (RAVON), St. Eustatius National Parks Foundation (STENAPA) and the University of Amsterdam (UvA).

 

The Lesser Antillean Iguana

The Lesser Antillean Iguana (Iguana delicatissima) is an endangered endemic of the Lesser Antilles, where its historic range lies between the islands of Anguilla and Martinique. However due to habitat destruction, hunting, invasive predators and invasive Green Iguanas (Iguana iguana) the Lesser Antillean Iguana currently inhabits less then 30% of its historic range (van den Burg et al. 2018a). Today, ongoing invasions of Green Iguanas and displacement and hybridization with subsequent introgression are the main threat to the Lesser Antillean Iguana (Knapp et al. 2014; van den Burg et al. 2018a).

 

St. Eustatius

The Lesser Antillean Iguana population on St. Eustatius (Dutch Caribbean) was believed to be free of hybridization and Green Iguana presence until early 2016 (van den Burg 2016; van den Burg et al. 2018b) when an adult female Green Iguana was captured (Jesse et al. 2016). Several months later, mid-2016, the first iguana with hybrid characteristics was found on St. Eustatius and several others were found during 2016 and 2017 (van den Burg et al. 2018b). We assessed the status of these individuals by analyzing their morphology (Breuil 2013) and several genetic markers and show that these are indeed hybrids between both species of Iguana (van den Burg et al. 2018). Our collected data suggests that this Green-Iguana invasion and hybridization is of recent origin and that at least 2 clutches with hybrid iguanas have hatched. Therefore actions aimed to prevent further hybridization and remove currently present hybrids from St. Eustatius are still relatively cheap and we are still in the first stage of invasion, meaning that if you act quick there is a chance of stopping its spread and eventually eliminating it.

 

This project

The focus of our study is to conduct the first stage of a long and multi-phased project that aims to remove all non-native iguanas from St. Eustatius and help prevent future invasions. During this first phase, we will collect baseline data on the distribution and abundance of native and non-native iguanas on St. Eustatius. Those data will thereafter be used to identify and target priority areas focusing on removing non-native iguanas from these areas. In addition, we will discuss and assess the current biosecurity measures on St. Eustatius and collaborate with local authorities to identify and implement improvements that will prevent future invasions. Further, we will collect genetic samples from all non-native iguanas that we find and analyze where these animals came from and whether they are F1 or >F1 hybrids. The latter would mean that hybrids already became sexually reproductive and thus reproduced with other native/non-native iguanas. Lastly, we will continue to create outreach and understanding for this endangered species and increase public awareness through presentations, radio talks, newspaper articles, and engaging with children through school visits and excursions.

 

We are currently preparing for our fieldwork period that will run from early July to November, during which a team of experienced iguana researchers will on St. Eustatius performing this study. Check back for updates on our project's progress!

 

Update May: 

Read our latest published paper on this iguana population and the threat of hybridization on the Journal of Heredity webpage here.

 

Read the latest update about the situation on St. Eustatius and upcoming work:

http://www.dcbd.nl/sites/www.dcbd.nl/files/documents/BioNews-13.pdf 

 

Update June:

We are excited to announce that a successful grant application through the Chicago Board of Trade Endangered Species Fund has helped to cover our total budget. In addition, all travel arrangements for the research team have been made!

 

Read the latest publication made possible with funds from the MbZ Fund here.

 

Update July:

The Lesser Antillean Iguana is now assessed as being critically endangered following guidelines by the International Union for Conservation of Nature, this new assessment was just published with the main applicant of this MbZ grant as the lead author, read the assessment here. 

 

Update early September:

The research team has currentyl carried out 47 transects, and found 10 nest sites that will be visited frequently when the hatching season comes closer so that many, if not all, hatchlings can be studied and assessed for hybrid presence. No hybrid or Green iguanas have been seen since May 2018 and March 2017, respectively, despite over a 130 man-hour search effort during these last 2 months.

Check here for a Dutch article on our project: https://www.naturetoday.com/intl/nl/nature-reports/message/?msg=24592 

 

Update early 2019

In December 2018 we published a scientific note in which we present a new insight on the major threat to this species. Namely, through hybridization with Iguana iguana, the Lesser Antillean Iguana is slowly being outcompeted. Data collected by us suggests that hybrid iguanas, just as Iguana iguana, have larger clutch size than Lesser Antillean Iguanas; which is likely a mechanism by which the later species is being outcompeted and replaced.

Link: https://www.biotaxa.org/hn/article/view/38874/37767 

 

 

 

 

 

 

References

Breuil M, Day M, Knapp CR (2010a) Iguana delicatissima. The IUCN Red List of threatened species 2010.

Breuil M (2013) Caractérisation morphologique de l’iguane commun Iguana iguana (Linnaeus, 1758), de l’iguane des Petites Antilles Iguana delicatissima Laurenti, 1768 et de leurs hybrides. Bulletin Société Herpetologique de France, 147:309–346.

Jesse WAM, Madden H, Molleman J, van Wagensveld T (2016) First recorded introduction for the Saba anole (Anolis sabanus) and an overview of introduced amphibians and reptiles on St. Eustatius. IRCF Reptiles and Amphibians, 23:144–46.

Knapp CR, Breuil M, Rodrigues C, Iverson JB (2014) Lesser Antillean Iguana, Iguana delicatissima: Conservation Action Plan, 2014—2016. IUCN SSC Iguana Specialist Group, Gland, Switzerland.

van den Burg MP (2016) St. Eustatius’ iguana population: pure Iguana delicatissima, but extreme low levels of genetic diversity. Thesis, University of Amsterdam.

van den Burg MP, Meirmans PG, van Wagensveld TP, Kluskens B, Madden H, Welch ME, Breeuwer JAJ (2018) The Lesser Antillean Iguana (Iguana delicatissima) on St. Eustatius: genetically depauperate and threatened by ongoing hybridization. Journal of Heredity. doi: 10.1093/jhered/esy008