Andros Iguana Rapid Ecological Assessment
Author: Charles Knapp
Conservation and Research for Endangered Species (CRES)
Zoological Society of San Diego
The Bahamian Andros iguana (Cyclura cychlura cychlura) is the largest native terrestrial vertebrate, and the only iguana in the Bahamas that is not confined presently to small cays. Consequently, the lizards face unique anthropogenic pressures relative to other islands in the archipelago and is listed as Endangered under 2004 IUCN Red List criteria.
In 2002, the Bahamian government and the Bahamas National Trust (BNT), the non-government organization mandated with managing national parks in the country, established the Central Andros National Parks (total area 115,770 ha). These parks were established to protect inland forest, coral reef, and wetland nursery areas on North Andros Island. At the time, no detailed ecological data were available for the endemic iguana. Therefore, little input concerning iguana habitat requirements or current distribution patterns were incorporated in delineating protected area boundaries. As a result, the current national parks are not ideal for iguana conservation because, relative to other localities, they are located in areas with historically degraded iguana habitat, feral non-indigenous mammalian predators, relatively high human population density, and a history of illegal hunting pressure.
In 2006 scientists conducted a rapid ecological assessment of the marine and terrestrial ecosystems on the west side of North Andros Island. One goal of the assessment was to fill information gaps on the distribution of high-profile endangered species such as flamingos, sea turtles, and iguanas. A critical oversight in the 2006 assessment, however, was neglecting the south end of Andros Island. Without a formal assessment of South Andros Island, comprehensive data necessary to identify critical conservation zones across the entire island were lacking.
The 2006 assessment revealed that the west side of North Andros Island was not ideal iguana habitat. Consequently, demarcating additional national parks in these areas would not benefit the endangered endemic iguana. Despite this information, plans were developing to recognize the area as a priority for establishing national parks. The current assessment of South Andros Island, therefore, was conducted to record comprehensive distributional patterns for the Andros Iguana throughout its range. This information is critical to make informed recommendations to the Bahamian government concerning protected area boundaries. Objectives for the assessment included 1) locating areas of relatively high iguana density and correlating density with environmental variables, and 2) conducting general herpetofauna surveys to produce species distribution lists. To increase the breadth of the survey, a sea turtle assessment team was included to determine species composition, demography, and relative abundance of sea turtles from South Andros. Both teams also gave presentations at local forums on South Andros Island and Mangrove Cay. The forums were organized to discuss with Androsians the importance of iguana and sea turtle conservation, and the scientific process involved with demarcating protected areas.
From 27 September to 5 October 2007 teams of scientists, bone fishing guides, and local students conducted visual encounter surveys from 30 sites located south of Lisbon Creek. We visited up to seven sites per day for 10 to 120 minutes. A total of 68.3 person hours (0.5 to 8.0 person hours per site) was tallied searching for iguanas. Ninety-seven iguanas were observed at 19 sites (63% of 30 sites), while recent tracks were observed at another site. No feral animals were observed from any location. The isolated small and large cays of the southern area of Andros are relatively pristine in comparison to North Andros. No roads exist in these areas and feral pigs are non-existent. Additionally, commercial logging practices have never been initiated in the area. These isolated localities support the largest pines remaining in the Bahamas and are areas of high conservation priority for iguanas. The Andros iguana relies on diverse habitats for survival and the responsible demarcation of protected areas for the species in the southern segment of Andros Island would benefit island-wide biodiversity. Based on this survey and past research, large protected areas should encompass Sandy Cay in South Bight and adjacent Alcorine Cay down to Grassy Creek. Meetings will be held in Nassau, Bahamas in February 2008 to discuss the importance of setting aside protected areas for the endemic Andros Iguana.
This survey was supported by an anonymous donor with funds distributed via the International Iguana Foundation. Tiamo Resorts provided crucial lodging and logistical assistance. Our guides, Marvin Miller and Ornald Shine, were invaluable with their knowledge of the labyrinth of South Andros waterways. Rivean Riley and Tamica Rahming from the Bahamas National Trust helped in the ground surveys and facilitation process. Adam Mitchell and Joe Wasilewski donated their time and personal expense to assist with the assessments. The students of Andros who participated in this survey were enthusiastic and with any luck their enthusiasm will be contagious to their peers. Felicity Burrows organized the local public forums so we could discuss the importance of iguana and sea turtle conservation.