Translocation of the St. Croix ground lizard to Buck Island Reef National Monument, St. Croix, U.S. Virgin Islands

Summary

The St. Croix ground lizard (Ameiva polops), Critically Endangered and extirpated from St. Croix proper by invasive mongooses since 1968, survived only in two small natural populations on Protestant Cay and Green Cay plus one earlier introduced population on Ruth Island, before Texas A&M University researchers and the National Park Service translocated 57 adults (32 males, 25 females) from Green Cay to Buck Island Reef National Monument in May 2008, after park staff eradicated mongooses and invasive rats there. Lizards, including several gravid females and courting pairs to maximize early reproduction, were individually marked with toe-clips and colored glass beads and held in eight predator-proof 10x10 meter enclosures for about two months to habituate them and allow intensive monitoring before enclosures were removed in July 2008. Visual surveys detected only 20 of the 57 released lizards due to low detectability, and bead marks and enclosure-based recapture proved unreliable, but body-condition data from recaptured individuals showed significant improvement, and gravid females began laying eggs almost immediately, with hatchlings appearing within two months. One year after release, surveys found 11 lizards, only two of them originally translocated, the rest wild-hatched gravid females and juveniles born on Buck Island, and by three years post-translocation the population included multiple hatchling cohorts alongside growing adults. Major difficulties included unreliable recapture methods and constrained funding met largely through in-kind agency and volunteer support. The project rates itself Highly Successful, having exceeded all its short- and long-term breeding and dispersal indicators.