Study

Conservation of the endangered San Salvador rock iguanas (Cyclura rileyi rileyi): population estimation, invasive species control, translocation, and headstarting

  • Published source details Hayes W.K., Cyril Jr S., Crutchfield T., Wasilewski J.A., Rothfus T.A. & Carter R.L. (2016) Conservation of the endangered San Salvador rock iguanas (Cyclura rileyi rileyi): population estimation, invasive species control, translocation, and headstarting. Herpetological Conservation and Biology, 11, 90-105.

Actions

This study is summarised as evidence for the following.

Action Category

Remove or control predators using lethal controls: Snakes & lizards

Action Link
Reptile Conservation

Translocate adult or juvenile reptiles: Lizards

Action Link
Reptile Conservation

Breed reptiles in captivity: Lizards

Action Link
Reptile Conservation
  1. Remove or control predators using lethal controls: Snakes & lizards

    A before-and-after study in 1994–2013 on an offshore cay in San Salvador, Bahamas (Hayes et al. 2016) found that using rodenticides to control invasive black rats Rattus rattus did not increase the abundance of San Salvador rock iguana Cyclura rileyi rileyi. Results were not statistically tested. The authors reported that following the eradication of black rats, abundance of San Salvador rock iguanas did not increase (population estimate after rat eradication: 28–159 iguana; population estimate before 36–144 iguanas). Black rats were controlled using rodenticide (brodifacoum) administered in wax blocks in covered bait stations in 1999 and 2000 (see original paper for detailed methods) on an island (25 acres). In summer 1999, the eradication attempt failed due to bait station design. Eradication was considered successful in summer 2000. San Salvador rock iguana were surveyed across the whole island in 1994, 1998–2007 and 2012–2013 (3 years before eradication and 9 years after eradication) using visual encounter surveys.

    (Summarised by: Katie Sainsbury)

  2. Translocate adult or juvenile reptiles: Lizards

    A replicated study in 2000–2013 on an offshore cay in San Salvador, Bahamas (Hayes et al. 2016) found that two translocated populations of San Salvador rock iguanas Cyclura rileyi rileyi, survived at least seven years in the wild but there was only evidence of breeding in one population. At least two years after a first translocation, five marked San Salvador rock iguanas and one subadult were observed (confirming breeding had taken place in the wild) and three unmarked iguanas were trapped; after five more years, two adult iguanas were observed. The authors reported that no iguanas from this translocation had survived after 12 years. Seven years after a second translocation, 12 of 14 adult iguanas were still alive, but there was no evidence of breeding in the wild. The first translocation was unsanctioned and took place in November 2000 (or earlier) with at least five individually-marked iguanas translocated to a private resort. The authors reported that feral cats Felis catus, dogs Canis lupus familiaris and rats Rattus rattus were removed from the resort. The authors observed and trapped these iguanas in October 2002, June 2007 and interviewed resort staff about them in 2012. In February 2005 a second translocation of 14 adult iguanas from a neighbouring island took place. These iguanas were surveyed in June 2006 and 2007, January and May 2012, and June 2013.

    (Summarised by: Katie Sainsbury)

  3. Breed reptiles in captivity: Lizards

    A study in 2012–2014 in an outdoor enclosure in San Salvador, Bahamas (Hayes et al. 2016) found that housing wild adult San Salvador rock iguanas Cyclura rileyi rileyi together in captivity did result in breeding and egg laying, but only one egg hatched successfully. Six months after bringing wild iguanas into captivity, one young iguana hatched successfully. In the subsequent two years, although gravid females dug burrows and deposited eggs, no hatchlings emerged. A breeding facility was established in May 2012, and eight adult iguanas (3 males and 5 females) were brought into captivity from the wild and housed in an outdoor enclosure (9 x 6 m).

    (Summarised by: Katie Sainsbury)

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