Overview

Brief Summary

Biology

Foraging during the day both in trees and on the ground, this species primarily feeds on flowers, fruits, young buds and leaves. Allen's Cay iguana is also reported to be opportunistically carnivorous, and tourists regularly feed them everything from table scraps to fresh produce. Unusually, a report also exists that the Exuma Island iguana is coprophagous, actively foraging for the faeces of the zenaida dove, Zenaida leucocephala, and the white-crowned pigeon, Columba leucocephala (2). The Allen's Cay iguana has been seen mating in mid-May, followed by nesting from mid to late June, whereas that Andros iguana mates in April, nesting in May and June (4). Cyclura species usually dig a subterranean nest chamber in sand or soil. However, Andros iguanas predominantly use termite mounds, providing a dry habitat and a relatively high and constant temperature for egg incubation (4). Although initial attempts by Allen's Cay iguanas at digging nest burrows are often abandoned, females defend the burrow site during the entire time of construction, and most continue that defence for at least three to four weeks after nest completion between mid-June and mid-July (5). Conversely, while female Exuma Island iguanas have also been observed actively defending an incomplete nest, they do not appear to protect the nest site after their eggs have been laid (2). Although not all females will reproduce each season, the largest Allen's Cay iguana females usually nest annually. Clutch size ranges between one and ten eggs, with larger, older females typically producing larger clutches. Allen's Cay iguana hatchlings apparently emerge in late September and early October, after about 80 to 85 days incubation (5). Clutch sizes for the Andros iguana range from 4 to 19 eggs. After approximately 75 days incubation, hatchling Andros iguanas emerge in August and September. Female sexual maturity is not attained until approximately 12 years of age in the Allen's Cay iguana and 8 years of age in the Andros iguana, but this very slow rate of development is offset by a long lifespan of up to 40 years (4) (6).
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Description

Like other West Indian rock iguanas (Cyclura spp.), the northern Bahamian rock iguana is a large and robust 'dinosaur-like' lizard with an impressive crest of spiny scales running down its back and a variable array of bright and beautiful colours, particularly between the three subspecies. The Andros Island iguana is dark grey to black, with yellowish tinged scales on the legs, dorsal crest, and particularly the head. With maturity, however, this yellow slowly changes to a warm orange-red, especially in large males. The Exuma Island iguana is generally regarded as the smallest of the three subspecies, although size may vary between populations as colouration does. Adults from Bitter Guana and Gaulin Cays are a dull grey-black interspersed with pale grey spots. The crest scales are either white or pale red, while scales on the head are black, tinged with orange on the snout. Adults from Guana Cay are dull black with a white throat and belly, either grey, red-tinged or scarlet dorsal crest, and light blue head and face. Allen's Cay iguana is grey-black with cream, pink or orange mottling (2).
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Distribution

Range Description

Found on Andros and Exuma Islands, The Bahamas. Extent of occurrence is <20,000 km². At least three main subpopulations are known on Andros and 13 subpopulations in the Exuma Islands.
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Continent: Caribbean
Distribution: Bahamas (Andros I, Exuma Cays)  Cyclura cychlura cychlura: Bahama Is.: Andros I.
Type locality: "Caroline"; restricted by Schwartz and Carey, 1977, to Andros Island, Bahama Islands.  Cyclura cychlura figginsi (HOLOTYPE MCZ 17745): Bahama Is.: central and southern Exuma Cays.  Cyclura cychlura inornata (HOLOTYPE MCZ 11062): northern Exuma Cays.
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Range

This iguana is native to Andros and the Exuma Islands of the Bahamas (1). As its common name suggests, the Andros Island iguana inhabits Andros Island, the largest of the Bahamian Islands, while the Exuma Island iguana occurs on seven small cays scattered throughout the central and southern Exuma Island chain. Allen's Cay iguana is also found in the Exuma Island chain, where only two breeding populations are known in the north, on leaf Cay (four hectares) and U Cay (also known as Southwest Allen's Cay; three hectares). A handful of adults also live on Allen's Cay (seven hectares), but there has as yet been no evidence of breeding there (2).
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
Preferred habitats are tropical dry forest, pine barrens, coastal coppice, mangrove and beach strand vegetation areas.

Cyclura cyclura is a herbivorous, ground dwelling, saxicolous species using limestone crevices, or burrows constructed in sandy loam, as retreats. Juveniles and subadults often climb trees and shrubs in the morning to feed and bask. Hollows in dead trees often are used as retreats for juveniles. The islands are low-relief (< 20 m above sea level) karst limestone platforms.

Average generation length is around 20 years.

Systems
  • Terrestrial
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Preferred habitats include tropical dry forest, pine barrens, coastal coppice, mangrove and beach strand vegetation areas (1), while limestone crevices and burrows in the sand provide suitable retreats at night and in adverse weather conditions (2).
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Life History and Behavior

Life Expectancy

Lifespan, longevity, and ageing

Maximum longevity: 23.4 years (captivity)
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
VU
Vulnerable

Red List Criteria
A2bce; B1ab(i,ii,iii,iv,v)

Version
3.1

Year Assessed
2004

Assessor/s
Knapp, C.R., Iverson, J.B. & Buckner, S.

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

Contributor/s

Justification
Cyclura cychlura is endemic to the Bahamas. Extent of occurrence is < 20,000 km² and the population is fragmented: at least 16 subpopulations are known existing in a fragmented habitat. Habitat is declining in area and quality due to logging, urban and transport developments, feral animals (cats, dogs, hogs, goats) and fire. It is estimated that there has been a decline in habitat area of at least 20% over the last 30 years. In addition to this, the species is hunted locally for food and for the international pet trade. It is estimated that the current global population is less than 5,000 and is declining: the population has decreased by at least 50% over the last 60 years (three generations). Currently assessed as Vulnerable.

The three subspecies within Cyclura cychlura are also included on the IUCN Red List: C. c. cychlura (Endangered); C. c. figginsi (Endangered); and C. c. inornata (Endangered).

History
  • 1996
    Vulnerable
  • 1994
    Rare
    (Groombridge 1994)
  • 1990
    Rare
    (IUCN 1990)
  • 1988
    Rare
    (IUCN Conservation Monitoring Centre 1988)
  • 1986
    Rare
    (IUCN Conservation Monitoring Centre 1986)
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Status

Classified as Vulnerable (VU) on the IUCN Red List 2007 (1) and listed on Appendix I of CITES (3). Subspecies: Cyclura cychlura cychlura (Andros iguana, Andros Island iguana or Andros Island rock iguana) is classified as Endangered (EN); C. c. inornata (Allen's Cay iguana or Allen's Cay rock iguana) is classified as Endangered (EN), and C. c. figginsi (the Exuma Island iguana or Exuma Island rock iguana) is classified as Critically Endangered (CR) on the IUCN Red List 2007 (1). All subspecies are listed on Appendix I of CITES (3).
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Population

Population
The current global population is less than 5,000 and is declining. Of the three subpopulations on Andros, there are <500 in the northern part of the island, <1,500 in the middle, and <2,000 in the south part of the island. Satellite cays hold < 1,000. Subpopulation sizes in the Exuma Islands are: Bitter Guana Cay (20–50); Gaulin Cay (275–325); White Bay Cay (200–250); Noddy Cay (200–250); North Adderly Cay (235–275); Leaf (< 10); Guana Cay (80–90); Pasture Cay (16); Alligator Cay (75–90); Leaf Cay north of Highbourne Cay (500); U-Cay (300); Allen Cay (15); Flat Rock Cay (10).

Population Trend
Decreasing
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Threats

Major Threats
On Andros Island, there is island-wide logging, construction of homes and roads, feral animals and fire for agriculture or crab hunting. In the Exumas, main threats to the species are feral animals (e.g., goats), fire caused by tourists, and rapid private land acquisition. A direct threat to the population is hunting. This species is the target of illegal subsistence hunting for the animal's meat, and collection for the international pet trade.

The species inhabits two distinctly different island areas in the Bahamas. The Andros population is threatened based on the acceleration of perturbations, such as habitat loss, feral animals, and subsistence hunting. Although the island is large and some undisturbed subpopulations exist, it is only a matter of time before humans or feral animals degrade the populations. A suggestive north/south trend in population decline is noted and procedures must be implemented to stop further degradation of populations and habitat. The Exuma Island populations inhabit an area that is becoming increasingly popular with tourists- both as a sailing destination and region to buy islands. Increased human traffic brings potential and distinct deleterious consequences to the local flora and fauna. In 2004, a large-scale fire was reported on an iguana-inhabited island that has recently become a designated tourist destination. The fire is purportedly the result of a tourist cigarette. Also, in recent years there has been an increase in feral animals and wildlife smuggling throughout the islands. Continued population monitoring must be a priority along with recognizing that the fragmented population faces a precarious future.
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The Andros population is threatened by habitat loss as a result of island-wide logging, and construction of homes and roads (1). Additionally, feral pigs, which have proliferated and expanded their range, are known to root out eggs from iguana nests and pose a very real threat. Predation by feral and domestic dogs also threatens both juvenile and adult animals. Subsistence hunting is thought to continue, with many local residents apparently unaware of the protected status of the Andros Island iguanas (2). The main threats to the subspecies in the Exumas include the growing tourism industry there and the potential damage caused by increased human traffic. For example, a large-scale fire occurred in 2004 on an iguana-inhabited island that had recently become a tourist destination, purportedly the result of a tourist cigarette. Many of the islands are private, and are rapidly being bought for development. Illegal hunting is a serious concern, both for food and for the pet trade, and feral animals also pose a significant threat (1). Additionally, hurricanes in the area could endanger certain populations (2).
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Management

Conservation Actions

Conservation Actions
Cyclura cychlura is included in CITES Appendix I. At the national level, the species is protected by the Wild Animals (Protection) Act, 1968 for the Bahamas.

A new protected area on North Andros was declared in 2003. However, this is in an area of low iguana occurrence and is only protected on paper. There are no protection measures on the ground. In the Exuma Islands, protected areas include Pasture and Alligator Cays, Exuma Cays Land and Sea Park.

Captive populations exist in Ardastra Gardens, Nassau, The Bahamas; and Los Angeles Zoo.

Recommended actions include further surveys, genetic research, life history studies, investigation into the effects of current trade on the population, and a public education programme. A species management programme is recommended for The Bahamas.
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Conservation

Cyclura cychlura is included in CITES Appendix I, prohibiting international trade in the species, and like all Bahamian rock iguanas, is protected at the national level under the Wild Animals Protection Act of 1968 (1). Nevertheless, law enforcement is difficult for Allen's Cay iguanas without a warden present within its range. Although the warden of the nearby Exumas Land and Sea Park can potentially respond to reports of poaching, this is not always practical. Signs have been erected on the islands explaining the endangered status of these lizards. Since a small non-breeding population lives on Allen's Cay without suitable sandy areas for nesting, one suggested conservation measure is to dredge sand to upland areas, which could potentially double the available breeding habitat for this subspecies. A few captive individuals are kept at the Ardastra Zoo and Nature Centre Different on Abaco, and captive breeding is a key objective of the centre for the future (2). For the Andros Island iguana, a new area on the north of the island was given protected status in 2003, conferring a degree of safety. However, few iguanas inhabit this area, which is really only protected on paper, with no actual protection measures existing on the ground. Captive populations exist in Ardastra Gardens, Nassau, in the Bahamas, and Los Angeles Zoo in the U.S. (2). Ongoing research is documenting the potential threats facing the Exuma Island Iguana unique to each cay it inhabits, information that is designed to help the Bahamian government with setting appropriate conservation policies. Additionally, the suitable habitat on cays not currently supporting iguanas is being investigated for possible translocation programmes in the future. Signs are also erected on Gualin Cay notifying the public of the protected status of the iguanas. Protected areas in the Exumas include Pasture and Alligator Cays, Exuma Cays Land and Sea Park (2).
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Wikipedia

Northern Bahamian rock iguana

The northern Bahamian rock iguana (Cyclura cychlura) is a species of lizard of the genus Cyclura that is found on the Andros and Exuma islands in the Bahamas. Its status on the IUCN Red List is Vulnerable, with a wild population of less than 5,000 animals.[1]

Taxonomy[edit source | edit]

The northern Bahamian rock iguana's generic name Cyclura and specific name Cychlura are derived from the Ancient Greek cyclos (κύκλος) meaning "circular" and ourá (οὐρά) meaning "tail", after the thick-ringed tail characteristic of all cyclurids.[2] Its closest relatives are Cyclura nubila on Cuba, and Cyclura lewisi on Grand Cayman. All three apparently diverged from a common ancestor some 3 million years ago.[3]

There are three subspecies of the northern Bahamian rock iguana: the Andros Island iguana (Cyclura cychlura cychlura), Allen's Cay iguana (Cyclura cychlura inornata), and the Exuma Island iguana (Cyclura cychlura figginsi).[1][4] Biologist Catherine Malone describes C. c. cychlura as being phylogenetically different from C. c. figginisi and C. c. inornata but does not recognize them as separate species; the three are listed as subspecies until further study has been completed.[4][5]

Anatomy and morphology[edit source | edit]

This species, like other species of Cyclura, is sexually dimorphic; males are larger than females, and have more prominent dorsal crests and "horns" in addition to more prominent femoral pores on their thighs, which are used to release pheromones.[6][7]

Diet[edit source | edit]

Like all Cyclura species, the northern Bahamian rock iguana is primarily herbivorous, consuming leaves, flowers and fruits from over 100 different plant species. This diet is very rarely supplemented with insect larvae, crabs, slugs, dead birds and fungi.

Conservation[edit source | edit]

Status[edit source | edit]

It is estimated that the current global population of all three subspecies is less than 5,000 members and is declining.[8] The population has decreased by at least 50% over the last 60 years.[1]

Causes of decline[edit source | edit]

Hunting is the main factor threatening imminent extinction for this iguana.[1][8] It is the only Caribbean species of iguana which is still regularly hunted for food for human consumption.[1][8] Feral pigs pose a threat to the iguanas, as they dig up eggs from iguana nests within termite mounds.[1][8] Feral and domestic dogs prey upon juvenile and adult iguanas as well.[1][8] Feral goats have also been known to compete with the iguanas for food.[1]

As with other rock iguanas, their habitat is in rapid decline due to development and logging.[1]

References[edit source | edit]

  1. ^ a b c d e f g h i Knapp, C.R., Iverson, J.B. & Buckner, S. (2004). Cyclura cychlura. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on September 8, 2007.
  2. ^ Sanchez, Alejandro. "Family Iguanidae: Iguanas and Their Kin". Father Sanchez's Web Site of West Indian Natural History Diapsids I: Introduction; Lizards. Kingsnake.com. Retrieved November 26, 2007. 
  3. ^ Kenyon, Georgina (September 17, 2005). "Re-enter the Dragon". New Scientist (Simone Coless) (2517): 42–43. 
  4. ^ a b Hollingsworth, Bradford D. (2004). "The Evolution of Iguanas: An Overview of Relationships and a Checklist of Species". Iguanas: Biology and Conservation (University of California Press): 36–37. ISBN 978-0-520-23854-1. 
  5. ^ Malone,C.L.; Wheeler,T.; Taylor,J.F. & Davis,S.K (2000). Phylogeography of the Caribbean Rock Iguana (Cyclura): implications for conservation and insights on the biogeographic history of the West Indies. Mol. Phylogen. Evol. 17 ((2)). p. 269. 
  6. ^ De Vosjoli, Phillipe; David Blair (1992). The Green Iguana Manual. Escondido, California: Advanced Vivarium Systems. ISBN 1-882770-18-8. 
  7. ^ Martins, Emilia P.; Lacy, Kathryn (2004). "Behavior and Ecology of Rock Iguanas,I: Evidence for an Appeasement Display". Iguanas: Biology and Conservation (University of California Press): 98–108. ISBN 978-0-520-23854-1. 
  8. ^ a b c d e Morgan, Curtis (July 7, 2002). "In Bahamas Some Indulge Taste For Dwindling Iguana". Miami Herald. Retrieved 2007-10-14. [dead link]
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