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ISSN 2307-8235 (online)
IUCN 2008: T6031A12343361
Cyclura pinguis, Anegada Rock Iguana
Assessment by: Mitchell, N.
View on www.iucnredlist.org
Citation: Mitchell, N. 1996. Cyclura pinguis. The IUCN Red List of Threatened Species 1996:
e.T6031A12343361. http://dx.doi.org/10.2305/IUCN.UK.1996.RLTS.T6031A12343361.en
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THE IUCN RED LIST OF THREATENED SPECIES™
Taxonomy
Kingdom
Phylum
Class
Order
Family
Animalia
Chordata
Reptilia
Squamata
Iguanidae
Taxon Name: Cyclura pinguis Barbour, 1917
Common Name(s):
• English:
• French:
Anegada Rock Iguana, Anegada Ground Iguana, Anegada Island Iguana
Cyclure de l'Ile Anegada, Iguane terrestre de l'Ile Anegada
Assessment Information
Red List Category & Criteria:
Critically Endangered A1abcde, B1+2abce, C1+2b ver 2.3
Year Published:
1996
Date Assessed:
August 1, 1996
Annotations:
Needs Updating
Previously Published Red List Assessments
1994 – Endangered (E)
1990 – Endangered (E)
1988 – Endangered (E)
1986 – Endangered (E)
Geographic Range
Range Description:
The common name of the Anegada Island Iguana is misleading, as the animal was once distributed over
the entire Puerto Rico Bank. Fossils are known from Saint Thomas and Puerto Rico. Vulnerability to
predation by humans and their dogs and cats may have resulted in a contraction of its distribution to
Anegada.
Country Occurrence:
Native: Virgin Islands, British
© The IUCN Red List of Threatened Species: Cyclura pinguis – published in 1996.
http://dx.doi.org/10.2305/IUCN.UK.1996.RLTS.T6031A12343361.en
1
Population
Population density in 1968 was estimated at 2.03/ha (Carey 1975). In 1991, this figure had dropped to
0.36/ha in comparable habitat. Extrapolation of density estimates, distribution, and relative habitat
quality yields a population estimate for Anegada of 164 individuals. A small restored population also
exists on Guana Island with eight founding adults (Goodyear and Lazell 1994), from which three
juveniles have been translocated to Necker Island. The total population, including individuals on
Anegada, Guana, and Necker probably consists of fewer than 200 individuals.
30-50 left at last count on Anegada. Small population on another inhabited Cay put there some years
ago. Recent visits to Anegada reveal a continuing populations decline.
Habitat and Ecology (see Appendix for additional information)
Estimates in the late 1960s (Carey 1975) showed small home ranges for both sexes (less than 0.1 ha),
one principal burrow per animal, a 1:1 sex ratio, and habits that indicated monogamy (apparent pairs
inhabited separate but proximate burrows in a joint home range isolated from other pairs). The current
population structure is quite different. While previous studies may not have been sensitive to long
range movements, it now appears that home ranges are quite large on Anegada: males average 6.6 ha
and females average 4.2 ha. Home ranges broadly overlap and have one or two centers of activity. In
1991 the sex ratio had dropped to 1 female:2 males. Thus male competition for limited females may be
responsible for the high degree of home range overlap.
Burrows of both sexes may be located on the old limestone reef-tract or in sandy areas adjacent to it. If
available, iguanas will use additional holes or crevices as emergency retreats. Whereas degraded
vegetation may provide for male subsistence, it may not provide females with sufficient energy to allow
them both to produce eggs and compete with other animals for forage to support their own growth and
metabolism. Reproducing females may have low survivorship, resulting in the present skewed sex ratio.
Females usually lay one clutch of about 12-16 eggs per year in late spring or early summer.
Although largely facultative herbivores, all age-groups of these iguanas are opportunistic carnivores.
Invertebrates (beetles, caterpillars, centipedes, roaches) form less than 1% of the natural diet, although
this may be a result of limited availability. The bulk of the diet consists of leaves and fruits.
Over the past 20 years, grazing pressure by goats, sheep, burros, and cattle has radically changed the
vegetation composition of Anegada. The iguanas' diet is now composed of plant species the feral
animals reject.
Systems: Terrestrial
Threats (see Appendix for additional information)
Areas on Anegada that once contained dense populations of iguanas now support few or none.
Research indicates that this is due to three major causes, including competitive grazing pressure from
free-ranging livestock, predation by feral dogs, and predation of juveniles by feral cats. Competition with
livestock for food is the principal reason, although predation, habitat loss and a multiple year drought
are also having a negative impact.
© The IUCN Red List of Threatened Species: Cyclura pinguis – published in 1996.
http://dx.doi.org/10.2305/IUCN.UK.1996.RLTS.T6031A12343361.en
2
Conservation Actions (see Appendix for additional information)
A major grant has been received from the Environment, Science and Energy Department of the UK
Foreign Commonwealth Office to facilitate conservation activities on Anegada. Goals of this program
are to 1) implement a cat eradication/control feasibility study, 2) expand the current headstart facility, 3)
train the Senior Terrestrial Warden in iguana husbandry and facility maintenance, 4) conduct population
censusing and mapping at sites nesting sites and other potential sites where adults may be found, and
5) develop environmental education materials to raise public awareness of the importance and
vulnerability of iguanas on Anegada.
In the 1980s, eight iguanas were moved from Anegada to Guana Island, British Virgin Islands, to start a
second population in part of the species’ former range (Goodyear and Lazell 1994). This is not a
limestone island, and does not provide as many natural retreats as Anegada. In the absence of
introduced predators, however, the iguanas appear to do well and reproduce in areas that are free of
sheep (the only feral grazing competitor present). Currently, approximately 20 adult iguanas are
estimated to inhabit Guana. Offspring have been seen each year since 1987, but recruitment is very low
over much of the island. Guana Island Wildlife Sanctuary continues to try to rid the island of sheep,
which may improve the habitat for iguanas.
This species is listed on CITES Appendix I.
Credits
Assessor(s):
Mitchell, N.
© The IUCN Red List of Threatened Species: Cyclura pinguis – published in 1996.
http://dx.doi.org/10.2305/IUCN.UK.1996.RLTS.T6031A12343361.en
3
Bibliography
Alberts, A. (compiler and editor). 2000. West Indian Iguanas: Status Survey and Conservation Action
Plan. IUCN/SSC West Indian Iguana Specialist Group. IUCN, Gland, Switzerland and Cambridge, UK.
Baillie, J. and Groombridge, B. (eds). 1996. 1996 IUCN Red List of Threatened Animals. pp. 378.
International Union for Conservation of Nature, Gland, Switzerland and Cambridge, UK.
Carey, W.M. 1975. The rock iguana, Cyclura pinguis, on Anegada, British Virgin Islands, with notes on
Cyclura ricordi and Cyclura cornuta on Hispianola. Bulletin of the Florida State Museum of Biological
Sciences 19: 189-234.
Goodyear, N.C. and Lazell, J.D. 1994. Status of a relocated population of Iguana pinguis on Guana Island,
British Virgin Islands. Restoration Ecology 2: 43-50.
Groombridge, B. (ed.). 1994. 1994 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland and
Cambridge, UK.
IUCN. 1990. IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland and Cambridge, UK.
IUCN Conservation Monitoring Centre. 1986. 1986 IUCN Red List of Threatened Animals. IUCN, Gland,
Switzerland and Cambridge, UK.
IUCN Conservation Monitoring Centre. 1988. IUCN Red List of Threatened Animals. IUCN, Gland,
Switzerland and Cambridge, UK.
Citation
Mitchell, N. 1996. Cyclura pinguis. The IUCN Red List of Threatened Species 1996: e.T6031A12343361.
http://dx.doi.org/10.2305/IUCN.UK.1996.RLTS.T6031A12343361.en
Disclaimer
To make use of this information, please check the Terms of Use.
External Resources
For Images and External Links to Additional Information, please see the Red List website.
© The IUCN Red List of Threatened Species: Cyclura pinguis – published in 1996.
http://dx.doi.org/10.2305/IUCN.UK.1996.RLTS.T6031A12343361.en
4
Appendix
Habitats
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Habitat
Season
Suitability
Major
Importance?
1. Forest -> 1.5. Forest - Subtropical/Tropical Dry
-
Suitable
-
3. Shrubland -> 3.5. Shrubland - Subtropical/Tropical Dry
-
Suitable
-
12. Marine Intertidal -> 12.1. Marine Intertidal - Rocky Shoreline
-
Unknown
-
Threats
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Threat
Timing
Scope
Severity
Impact Score
2. Agriculture & aquaculture -> 2.3. Livestock farming
& ranching -> 2.3.4. Scale Unknown/Unrecorded
Ongoing
-
-
-
Stresses:
1. Ecosystem stresses -> 1.2. Ecosystem degradation
2. Species Stresses -> 2.3. Indirect species effects ->
2.3.2. Competition
Ongoing
-
Stresses:
2. Species Stresses -> 2.1. Species mortality
Ongoing
-
Stresses:
2. Species Stresses -> 2.3. Indirect species effects ->
2.3.7. Reduced reproductive success
8. Invasive & other problematic species & genes ->
8.1. Invasive non-native/alien species -> 8.1.2.
Named species (Canis familiaris)
8. Invasive & other problematic species & genes ->
8.1. Invasive non-native/alien species -> 8.1.2.
Named species (Felis catus)
-
-
-
-
Conservation Actions in Place
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Conservation Actions in Place
In-Place Education
Included in international legislation: Yes
Subject to any international management/trade controls: Yes
© The IUCN Red List of Threatened Species: Cyclura pinguis – published in 1996.
http://dx.doi.org/10.2305/IUCN.UK.1996.RLTS.T6031A12343361.en
5
The IUCN Red List Partnership
The IUCN Red List of Threatened Species™ is produced and managed by the IUCN Global Species
Programme, the IUCN Species Survival Commission (SSC) and The IUCN Red List Partnership. The IUCN
Red List Partners are: BirdLife International; Botanic Gardens Conservation International; Conservation
International; Microsoft; NatureServe; Royal Botanic Gardens, Kew; Sapienza University of Rome; Texas
A&M University; Wildscreen; and Zoological Society of London.
THE IUCN RED LIST OF THREATENED SPECIES™