After 12 weeks living in St. Croix, I have learned a lot about the various reptiles that call the US Virgin Islands home! Specifically, I have spent a lot of time with the St. Croix ground lizard, an endemic species that was extirpated from St. Croix because of land use changes and the introduction of invasive mammalian predators. The lizard survived on two offshore cays and subsequent conservation translocations have allowed their range to expand to four small islands and a small population back on mainland St. Croix.

The largest population of St. Croix ground lizards now reside on Buck Island, a 176-acre island managed by the National Parks Service. In 2008, just 52 lizards were brought to Buck Island from Green Cay National Wildlife Refuge and their population really took off! By 2013 – just five years after this translocation – 1,473 St. Croix ground lizards were estimated to live on Buck Island and occupy almost half its area (Angeli et al. 2018). Another population survey of ground lizards occurred in 2019, but prior to this summer this data had not been analyzed. This is where I come in!

colored maps showing lizard distribution changes between 2013 and 2019. In 2019, lizard abundance was more uniform and across entire island and in 2013 lizards were concentrated in one area.
Maps showing interpolated St. Croix ground lizard abundance in 2013 (top) and 2019 (bottom). In 2013, abundance was concentrated on the west side where the lizards were introduced and they were completely absent in the eastern half of the island. By 2019, ground lizards had occupied the entire island at a more uniform density.

My summer as an SIP Fellow was spent primarily assessing how the distribution and site abundance of St. Croix ground lizards on Buck Island had changed from 2013 to 2019 and setting up an easy-to-use model so that consistent analysis can be done for future surveys. My model showed that there were significantly more ground lizards in 2019 than 2013 and that their range had expanded across the entire length of the island! I am happy to report that the population of St. Croix ground lizards on Buck Island is doing well and now encompasses several thousand individuals. Future research will teach us more about this species to better motivate subsequent translocation efforts back into its historic range.

In addition to the St. Croix ground lizard, I have encountered a variety of other reptile species throughout my time in St. Croix. I’ve swam with sea turtles (green and hawksbill) and seen them nesting at night on the beach (leatherback), saw a tiny blindsnake, and caught a variety of lizard species including St. Croix anoles, Beatty’s least geckos, and even green iguanas. I am grateful I was able to spend my summer on a beautiful island with a such rich culture and remarkable biodiversity!

SIP Fellow Nicole Stevens SCUBA diving with a green sea turtle (left), holding a green iguana (middle), and holding a Beatty’s least gecko (right). Photo credits (left to right): Kristen Ewen, Mark Walenta, Nicole Stevens

Reference

  • Angeli, N.F., Lundgren, I.F., Pollock, C.G., Hillis-Starr, Z.M., Fitzgerald, L.A. (2018). Dispersal and population state of an endangered island lizard following a conservation translocation. Ecological Applications 0(0). 1-12.
Posted byNicole Stevens