Cyclura lewisi

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	REPTILIA	SQUAMATA	IGUANIDAE

Scientific Name:

Cyclura lewisi

Species Authority

Harlan, 1825

Infra-specific Authority:

Grant, 1940

Common Name/s:

English

–

Cayman Island Ground Iguana, Grand Cayman Blue Iguana, Grand Cayman Iguana

Synonym/s:

Cyclura nubila ssp. lewisi

Assessment Information [top]

Red List Category & Criteria:

Critically Endangered A2abce; B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v); C2a(i); D ver 3.1

Year Assessed:

2004

Assessor/s

Burton, F.J.

Evaluator/s:

Hudson, R. & Alberts, A. (Iguana Red List Authority)

Justification:
Extent of occurrence is declining rapidly and was estimated at less than 4 km² in 2002. The remnant unmanaged population was estimated between 10–25 individuals in 2002 (Burton 2002) and appears to be almost functionally extinct. The area of occupation halved between 1993 and 2002, with the population density within the area of occupation falling by 80% in the same period. Invasion of the area of occupation by dogs and residential development, and conversion of traditional fruit farms to cattle grazing has reduced the area of viable habitat severely in the last decade. Road kills, illegal capture, non-native predators (rats, cats, dogs), continue to prevent recruitment to the adult population, and are also killing/removing breeding age adults. Conservation efforts are showing small scale success in rebuilding a managed breeding population in a 26 ha protected area (the Queen Elizabeth II Botanic Park) on Grand Cayman. The unmanaged wild population is expected to be extinct in the next 5–10 years since the major threats continue unabated.

History:

1996

–

Critically Endangered (Baillie and Groombridge 1996)

Geographic Range [top]

Range Description:	Previously listed as Cyclura nubila lewisi, this taxon has recently been recognized as a full species, Cyclura lewisi Grant by the IUCN-SSC Iguana Specialist Group, in light of genetic data (Malone et al. 2000) and a review currently in press (Burton 2004). Although fossil evidence indicates this species was formerly widespread in dry and coastal habitats throughout Grand Cayman, it is currently restricted to the East interior, in the High Rock-Battle Hill area, with extremely rare occurrences south of the Queen’s Highway. The area of occurrence was estimated at 7 km² in 1993, reduced to less than 4 km² by 2002 despite the new establishment of a managed wild population on the Queen Elizabeth II (QE II) Botanic Park, which began breeding in 2001 (Burton 2002).
Countries:	Native: Cayman Islands

Range Description:

Previously listed as Cyclura nubila lewisi, this taxon has recently been recognized as a full species, Cyclura lewisi Grant by the IUCN-SSC Iguana Specialist Group, in light of genetic data (Malone et al. 2000) and a review currently in press (Burton 2004).

Although fossil evidence indicates this species was formerly widespread in dry and coastal habitats throughout Grand Cayman, it is currently restricted to the East interior, in the High Rock-Battle Hill area, with extremely rare occurrences south of the Queen’s Highway. The area of occurrence was estimated at 7 km² in 1993, reduced to less than 4 km² by 2002 despite the new establishment of a managed wild population on the Queen Elizabeth II (QE II) Botanic Park, which began breeding in 2001 (Burton 2002).

Countries:

Native:

Cayman Islands

Population [top]

Population:	The unmanaged wild population is so sparse and dispersed (estimated at 10–25 individuals in 2002) that no meaningful assessment of subpopulation structure can be made. The managed population in the QE II Botanic Park is not fenced in and some individuals released at this site have been recovered in the village of East End, indicating that there is potential genetic exchange with the unmanaged remnant population. However, predation by feral cats, combined with threats detailed below, appears to be preventing recruitment of young in the unmanaged population to breeding age (Burton 2002).
Population Trend:	Decreasing

Population:

The unmanaged wild population is so sparse and dispersed (estimated at 10–25 individuals in 2002) that no meaningful assessment of subpopulation structure can be made. The managed population in the QE II Botanic Park is not fenced in and some individuals released at this site have been recovered in the village of East End, indicating that there is potential genetic exchange with the unmanaged remnant population. However, predation by feral cats, combined with threats detailed below, appears to be preventing recruitment of young in the unmanaged population to breeding age (Burton 2002).

Population Trend:

Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	Comparison with other Cyclura species in the region strongly suggests there was once a coastal population of Cyclura lewisi, which was gradually displaced or extirpated by human settlements and the construction of a perimeter highway. The sparse interior population is believed to have been attracted to agricultural clearance, where in 1993 the remnant wild population was focused in the intergrade between dry forest/shrubland, and traditional fruit farms. The farms provided thermoregulatory opportunities, herbaceous browse, fallen fruit, and nesting soil, but also brought the iguanas into contact with people. Like all Cyclura, C. lewisi is an annual breeder, laying 1 to 22 eggs depending on the female’s age and size. Hatchlings are vulnerable to native snakes (Alsophis cantherigerus caymanus) and naturally have a very high mortality rate. Head-starting young through the first two years increases survival greatly, and is proving an effective medium-term conservation strategy.
Systems:	Terrestrial

Habitat and Ecology:

Comparison with other Cyclura species in the region strongly suggests there was once a coastal population of Cyclura lewisi, which was gradually displaced or extirpated by human settlements and the construction of a perimeter highway. The sparse interior population is believed to have been attracted to agricultural clearance, where in 1993 the remnant wild population was focused in the intergrade between dry forest/shrubland, and traditional fruit farms. The farms provided thermoregulatory opportunities, herbaceous browse, fallen fruit, and nesting soil, but also brought the iguanas into contact with people.

Like all Cyclura, C. lewisi is an annual breeder, laying 1 to 22 eggs depending on the female’s age and size. Hatchlings are vulnerable to native snakes (Alsophis cantherigerus caymanus) and naturally have a very high mortality rate. Head-starting young through the first two years increases survival greatly, and is proving an effective medium-term conservation strategy.

Systems:

Terrestrial

Threats [top]

Major Threat(s):	Feral and free-roaming dogs and cats kill adults and juveniles respectively and have been shown to be capable of causing local extinction of other Cyclura species in absence of other threats. Rats have also been observed to cause severe injury to C. lewisi hatchlings, and may cause mortality. Both cats and rats have been observed throughout all areas of remaining C. lewisi occurrence, and in 2002 dogs were seen in areas which had supported nesting C. lewisi as recently as 1993. Predation by feral exotics is regarded as one of the major threats to the species. Traditional fruit farms have been converted to grassland for cattle grazing on a large scale over the last decade. The loss of fruit trees and herbaceous browse, combined with soil compaction, means this conversion has drastically reduced the extent of suitable habitat for the iguanas. Increasingly land is being concerted for human residential purposes, witch brings an increase in rats, cats and dogs. Habitat conversion is the second major threat to the species. Vehicular roads to serve farms in inland residential subdivisions has brought fast-moving traffic into remnant iguana areas. Road killed iguanas have consequently been observed. Although the Blue Iguana is protected under local legislation, occasional illegal captures (not involving international trade) do occur. A large breeding population of Iguana iguana from Central America has become established on Grand Cayman. While no resulting direct threats to native iguanas have become evident, the presence of another iguana species confuses the public awareness messages for conservation of Cyclura lewisi. Occasional specimens of the closely related Cyclura nubila caymanensis from Little Cayman, have been found free in western Grand Cayman as a result of deliberate or accidental transport of hatchlings on boats and aircraft. No sightings have occurred in eastern Grand Cayman where C. lewisi persists, but there is clearly a potential risk of hybridization. Despite a former tradition of consuming tail meat of iguanas, modern day Caymanians do not generally eat iguanas. An increasing Central American immigrant population has, however, brought a tradition of consuming Iguana iguana to Cayman, and there is a danger than this practice could "cross over" to C. lewisi. The primary use of Blue Iguanas today is as a major ecotourism attraction: although the population was restored there for conservation reasons, it constitutes one of the main visitor attractions to the QE II Botanic Park. Under this controlled setting with exclusion of dogs and cats, this synergy is proving beneficial to both the Park and the iguanas.

Major Threat(s):

Feral and free-roaming dogs and cats kill adults and juveniles respectively and have been shown to be capable of causing local extinction of other Cyclura species in absence of other threats. Rats have also been observed to cause severe injury to C. lewisi hatchlings, and may cause mortality. Both cats and rats have been observed throughout all areas of remaining C. lewisi occurrence, and in 2002 dogs were seen in areas which had supported nesting C. lewisi as recently as 1993. Predation by feral exotics is regarded as one of the major threats to the species.

Traditional fruit farms have been converted to grassland for cattle grazing on a large scale over the last decade. The loss of fruit trees and herbaceous browse, combined with soil compaction, means this conversion has drastically reduced the extent of suitable habitat for the iguanas. Increasingly land is being concerted for human residential purposes, witch brings an increase in rats, cats and dogs. Habitat conversion is the second major threat to the species.

Vehicular roads to serve farms in inland residential subdivisions has brought fast-moving traffic into remnant iguana areas. Road killed iguanas have consequently been observed. Although the Blue Iguana is protected under local legislation, occasional illegal captures (not involving international trade) do occur.

A large breeding population of Iguana iguana from Central America has become established on Grand Cayman. While no resulting direct threats to native iguanas have become evident, the presence of another iguana species confuses the public awareness messages for conservation of Cyclura lewisi.

Occasional specimens of the closely related Cyclura nubila caymanensis from Little Cayman, have been found free in western Grand Cayman as a result of deliberate or accidental transport of hatchlings on boats and aircraft. No sightings have occurred in eastern Grand Cayman where C. lewisi persists, but there is clearly a potential risk of hybridization.

Despite a former tradition of consuming tail meat of iguanas, modern day Caymanians do not generally eat iguanas. An increasing Central American immigrant population has, however, brought a tradition of consuming Iguana iguana to Cayman, and there is a danger than this practice could "cross over" to C. lewisi.

The primary use of Blue Iguanas today is as a major ecotourism attraction: although the population was restored there for conservation reasons, it constitutes one of the main visitor attractions to the QE II Botanic Park. Under this controlled setting with exclusion of dogs and cats, this synergy is proving beneficial to both the Park and the iguanas.

Conservation Actions [top]

Conservation Actions:	The National Trust for the Cayman Islands owns and protects ca. 800 hectares of terrestrial protected areas, but within Grand Cayman suitable protected land for Cyclura lewisi is very scarce. The Blue Iguana Recovery Programme (under the auspices of the National Trust for the Cayman Islands) is successfully breeding C. lewisi in captivity, rearing them to two years old, and releasing them into the Queen Elizabeth II Botanic Park on Grand Cayman. This restored population began breeding in 2001. Currently nests laid in the Park are being collected, and the eggs incubated to allow head-starting of all hatchlings. Long term the programme seeks to expand this successful pilot project through establishment of a large protected area where a population of ca. 1,000 iguanas can be restored. Control of feral predators will be required in perpetuity. The species is fully protected under local legislation, and effectively kept out of international trade by CITES regulations and procedures.

Conservation Actions:

The National Trust for the Cayman Islands owns and protects ca. 800 hectares of terrestrial protected areas, but within Grand Cayman suitable protected land for Cyclura lewisi is very scarce. The Blue Iguana Recovery Programme (under the auspices of the National Trust for the Cayman Islands) is successfully breeding C. lewisi in captivity, rearing them to two years old, and releasing them into the Queen Elizabeth II Botanic Park on Grand Cayman. This restored population began breeding in 2001. Currently nests laid in the Park are being collected, and the eggs incubated to allow head-starting of all hatchlings. Long term the programme seeks to expand this successful pilot project through establishment of a large protected area where a population of ca. 1,000 iguanas can be restored. Control of feral predators will be required in perpetuity.

The species is fully protected under local legislation, and effectively kept out of international trade by CITES regulations and procedures.

Citation:	IUCN 2008. 2008 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 12 October 2008.
Disclaimer:	To make use of this information, please check the Copyright and Data Disclaimer.
Feedback:	If you see any errors or have any questions or suggestions on what is shown on this page, please fill in the feedback form so that we can correct or extend the information provided