Cuban iguana
Cyclura nubila nubila
By Antonio Perera
Description
The Cuban iguana reaches a very large adult size, with a mean SVL of 405mm for males and 320mm for females. This subspecies is usually gray in color, stippled or mottled with tan, and has a tan head and tail. Adults are somewhat greenish in color and may be stippled with yellow. The juvenile pattern consists of a series of five to ten pale chevrons which expand mid-dorsally to give a longitudinal series of subcircular or subrectangular pale blotches. Between the pale dorsal chevrons are black chevrons which form the margins of the lateral pale pattern. In adults, a conspicuous feature is very high dorsal crest scales (Schwartz and Carey 1977).
Distribution
The Cuban iguana is well distributed around Cuba, mainly in xerophilic coastal areas, but relatively safe populations are found only on some islets along the north and south coasts and in isolated protected areas on the mainland. These include Guanahacabibes Biosphere Reserve in the west, Desembarco del Granma National Park, Hatibonico Wildlife Refuge, Punta Negra-Quemados Ecological Reserve, and Delta del Cauto Wildlife Refuge, all in eastern Cuba (Fig. 5). This subspecies has also been introduced to Isla Magueyes, southwest of Puerto Rico. Because of its wide distribution, accurate information about the number of distinct subpopulations of Cuban iguanas is currently unavailable, yet it may be present on as many as 4,000 islets surrounding the Cuban mainland. The population on the U.S. Naval Base at Guantánamo Bay has been estimated at 2,000-3,000 individuals (A. Alberts and J. Phillips, unpublished data).
Status of populations in the wild
Not many decades ago, the subspecies was extremely widespread on Cuba. However, populations on the mainland have decreased dramatically or disappeared entirely in most areas since the end of the last century. On many islets, populations are still relatively safe, but this situation is changing with the transformation of many islets for tourist developments. Nevertheless, if strictly protected areas on the mainland and islets continue to remain untouched, 60 to 80% of the remaining population will probably be safe. Any population analyses should be carried out with two distinct components: one for populations living on the mainland, and one for populations inhabiting small islands and islets.
Subpopulations of the Cuban iguana show great variation in density according to habitat quality and level of protection. On three natural, undisturbed islets, Perera (1985b) found densities of 25.01/ha; 9.64/ha, and 4.42/ha. V. Berovides found densities of 7.7l/ha and H. González found densities of between 9 and 11/ha on Cayo Rosario. Those authors estimate the total population of Cayo Rosario to be 10,000 individuals. Recently, V. Berovides (personal communication) found a density of 40/ha on a rocky islet. The total population of this subspecies in Cuba is estimated at between 40,000 and 60,000 individuals.
In general, the population is declining, more quickly on the mainland than in other areas. Most disturbing is the rapidity of the loss of this subspecies in disturbed areas. Iguanas are now absent from the northeastern Havana coast, the Hicacos peninsula, and Key Largo, where they were known to be very abundant some 30-40 years ago. Whereas habitat transformation and disturbance on the mainland seem to be responsible for local extinctions, populations appear stable on many untouched islands and islets. Mainland populations have probably been declining at a rate of greater than 1% per year for the last ten years, primarily as a result of habitat alteration and interactions with domestic and feral introduced species, including cats, dogs, and pigs.
Ecology and natural history
Cuban iguanas can be found in relatively undisturbed xerophilic coastal lands on both mainland Cuba and surrounding islets, primarily in rocky limestone areas where natural refuges and appropriate nesting sites are available. Foraging is commonly observed in concentrations of coastal mangroves. In western Cuba, there is an isolated population inhabiting an inland karstic mountain area. Apparently, semiarid lands several kilometers inland from the coast can still support iguana populations.
The Cuban iguana is a phytophagous generalist, and the diversity of its diet depends on the floristic diversity and abundance of vegetation in each locality. Perera (1985a) found 25 different vegetation types in the diet of these iguanas. The most frequent plants (flowers, fruits, or leaves) in the diet were Andropogon, Avicenia, Canavalia, Capparis, Chrysobalanus, Conocarpus, Eragrostis, Lagun-cularia, Opuntia, Rachilcalis, Rizophora, Sporobolus, Strumpfia, Suriana, and Thrinax. If readily available with little effort, Cuban iguanas will also feed on animal matter. The most common animal item in the diet is the crab Cardisoma guandhumi. Some seasonal changes in diet are evident, especially during the rainy season when fruits from Opuntia, Chrysobalanus, Strumpfia, and Suriana become available.
Cuban iguanas reach sexual maturity at an age of two to three years. Reproductive behavior in this subspecies is similar to that described for other members of the genus. Males become aggressive, and vigorously defend territories in competition for females. Females lay 15 to 30 eggs annually in a single clutch in a nest which they dig in the sand.
Habitat
Previously suitable habitats have been losing the conditions necessary to support iguanas since 1900. Many coastal areas with sandy beaches have been progressively assimilated for tourist resort development. Although this process was initially restricted to the mainland, in recent years many islets have been rendered unsuitable for iguanas for the same reason. Even if habitat is not lost directly, the disturbances associated with development appear severe enough to cause iguana populations to disappear in some areas. Fig. 5 shows the area presently occupied by Cuban iguanas. It is possible to identify 12 historical concentrations of iguanas in the Cuban archipelago:
(1) Guanahacabibes peninsula: No major habitat transformation. The original distribution of iguanas remains basically unchanged, but density has decreased as a result of predation by feral dogs, cats, and pigs and local habitat destruction. In general, the area retains its natural features.
(2) Canarreos subarchipelago, including Isla de Juventad: The best remaining populations are located in this area, although some local extinctions due to habitat loss caused by fires or development of tourist resorts have been reported on Cayo Largo. On Isla de Juventad, iguanas are still abundant along the south coast and adjacent inland areas.
(3) Zapata peninsula: No major habitat transformation. Iguanas are still abundant in coastal areas and on surrounding islets. Density has declined in some areas as a result of predation by feral cats, dogs, and pigs and local habitat degradation.
(4) South coast and islets of Sancti Spiritus Province: In mainland coastal areas, iguana populations are highly impacted or extinct. On some islets, iguanas are still very abundant.
(5) Jardines de la Reina subarchipelago: A well-preserved subarchipelago with healthy populations of iguanas on some islets.
(6) Delta del Cauto Wildlife Refuge: Iguanas are abundant in sandy areas of the delta as well as on many islets.
(7) Desembarco del Granma National Park: One of the best preserved areas in the country which includes a marine limestone terrace system on which iguanas are particularly abundant.
(8) Santiago de Cuba and Guantánamo semi-arid coast: Although density has declined and distribution has contracted in some areas due to habitat loss and the introduction of exotic predators, good populations remain in some protected areas.
(9) Holguin Province coast: As above, although density has declined and distribution has contracted in some areas due to habitat loss and the introduction of exotic predators, good populations remain in some protected areas.
(10) Sabana-Camaguey subarchipelago and north-central coast of Cuba: This is the second major concentration of iguanas. Although some local extinctions have occurred due to habitat loss (Hicacos peninsula) and other areas are under pressure from tourist development, iguana populations are dense in protected areas.
(11) Northeast Havana coast: Almost all populations became extinct in the last 30 to 40 years as a result of habitat loss and transformation.
(12) Viñales: This is the only iguana population known to live inland. Iguanas inhabit some karstic hills, but their density is very low in this habitat.
Threats
Habitat transformation and human disturbance represent the main threats to Cuban iguana populations. Other important threats include predation by wild and domestic dogs on both adults and juveniles, predation by cats on juveniles, and egg predation by pigs. Hunting is not a major threat because there is not a widespread tradition of consumption of iguana meat or eggs.
Current conservation programs
With the exception of area 11 above, all of the major iguana concentrations are either partially or fully protected. Fig. 5 shows strictly protected areas, resource management areas, and gaps where iguanas are present but formal protection is lacking. At selected localities within the National System of Protected Areas, projects directed toward conservation and reproduction of Cuban iguanas are being carried out by the Centro Nacional de Areas Protegidas in collaboration with researchers from Havana University. Ecological and systematic studies are being conducted at the Institute of Ecology and Systematics, Cuban Academy of Sciences.
No captive programs currently exist within Cuba, but are a future component of the research-management program of the Centro Nacional de Areas Protegidas. Although a fairly large captive population exists within the U.S., a moratorium on breeding has been recommended to provide space for more critically endangered taxa (American Zoo and Aquarium Association, 1995).
Critical conservation initiatives
- Establishment of an integrated research and management program for Cuban iguanas within the national system of protected areas.
- Education of local people regarding the vulnerability of iguanas to feral dogs, cats, and pigs.
- Construction of facilities for forest guards.
Priority projects
- Conduct field research and surveys to assess the present status of the species in the wild, analyze habitat requirements, and identify natural and anthropogenic factors influencing iguana populations.
- Undertake natural history studies, including feeding ecology, social behavior, and reproduction. Results from these studies have the potential to serve as a valuable model for other, more endangered taxa.
- Establish an in situ captive breeding program, including development of methods for artificial and seminatural egg incubation.
Fig. 5. Distribution of the Cuban iguana and protected areas that cover iguana populations.
Strictly protected areas which cover iguana populations:
- El Veral Nature Preserve
- Cabo Corrientes Nature Preserve
- Cayos de San Felipe Wildlife Refuge
- Cayo Campos Wildlife Refuge
- Cayo Cantiles Wildlife Refuge
- Cayo Rosario Wildlife Refuge
- Las Salinas Wildlife Refuge
- Tunas de Zaza Wildlife Refuge
- Delta de Cauto Wildlife Refuge
- Desembarco del Granma National Park
- El Retiro Nature Preserve
- Hatibonico Wildlife Refuge
- Baitiquirí Nature Preserve
- Imías Nature Preserve
- Pan de Azucar Nature Preserve
- Tacre Nature Preserve
- Punta Negra-Quemados Ecological Preserve
- Cayo Caguanes National Park
Resource management areas which cover iguana populations:
- Guanahacabibes Biosphere Reserve
- Subarchipiélago de los Canarreos Multiple Use Area
- Subarchipiélago Jardines de la Reina Multiple Use Area
- Sierra Maestra Great National Park
- Subarchipiélago Sabana Camagüey Multiple Use Area
Contact persons
Antonio Perera
Centro Nacional de Areas Protegidas
Calle 18A No. 4114 e/ 41 y 47
Miramar Playa
Ciudad Habana, Cuba
Tel/Fax: (537) 240798
E-mail: tony.perera@cidea.unepnet.inf.cu
Amnerys González
Centro Nacional de Areas Protegidas
Calle 18A No. 4114 e/ 41 y 47
Miramar Playa
Ciudad Habana, Cuba
Tel/Fax: (537) 240798
Vincente Berovides
Facultad de Biologia
Universidad de la Habana
Calle 25 esq., Vedado
Ciudad Habana, Cuba
E-mail: elfos@esipr.columbus.cu
Orlando Garrido
Museo Nacional de Historia Natural
Capitolio Nacional, La Habana, Cuba
Pedro Pérez
Instituto de Ecologia y Sistemática
Academia de Ciencias de Cuba
Carretera de Varone km 3 1/2
Ciudad Habana, Cuba
Allison Alberts
Center for Reproduction of Endangered Species
Zoological Society of San Diego
PO Box 120551
San Diego, CA 92112 USA
Tel: (619) 557-3955
Fax: (619) 557-3959
E-mail: aalberts@sandiegozoo.org
