Northern Bahamian rock iguana (Cyclura cychlura)

Description

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Northern Bahamian rock iguana fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Northern Bahamian rock iguana 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⁾.

Also known as

Bahamas iguana, Bahamas rock iguana.

Synonyms

Cyclura baeolopha, Iguana cyclura.

Size

Total length: up to 150 cm ⁽²⁾

Northern Bahamian rock iguana 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)}.

Northern Bahamian rock iguana 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⁾.

Northern Bahamian rock iguana habitat

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⁾.

Northern Bahamian rock iguana 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⁾.

Northern Bahamian rock iguana threats

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⁾.

Northern Bahamian rock iguana 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⁾.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

For more information on the northern Bahamian rock iguana see:

• Alberts, A. (1999) West Indian Iguanas: Status Survey and Conservation Action Plan. IUCN/SSC West Indian Iguana Specialist Group, Gland, Switzerland and Cambridge, UK. Available at:
  www.iucn-isg.org/actionplan

Authentication

Authenticated (15/01/08) by Dr. Charles Knapp,Conservation and Research for Endangered Species (CRES), Zoological Society of San Diego
http://cres.sandiegozoo.org/ and Conservation Department, John G. Shedd, Aquarium
http://www.sheddaquarium.org/

Glossary

Barrens

A flat, open plains area dominated by grasses, supporting a growth of small trees, and lacking a closed-canopy forest; examples of barrens communities are pine barrens and oak barrens.

Carnivore

Flesh-eating.

Coprophagous

Feeding on dung, or faeces.

Dorsal

Relating to the back or top side of an animal.

Subspecies

A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.

Subterranean

Living underground, in caves or groundwater.

References

1. IUCN Red List (December, 2007)
   http://www.iucnredlist.org/
2. Alberts, A. (1999) West Indian Iguanas: Status Survey and Conservation Action Plan. IUCN/SSC West Indian Iguana Specialist Group, Gland, Switzerland and Cambridge. Available at:
   http://www.iucn-isg.org/actionplan/
3. CITES (May, 2006)
   http://www.cites.org/
4. Knapp, C.R., Iverson, J.B. and Owems, A.K. (2006) Geographic variation in nesting behaviour and reproductive biology of an insular iguana (Cyclura cychlura). Canadian Journal of Zoology, 84: 1566 - 1575.
5. Iverson, J.B., Hines, K.N. and Valiulisc, J.M. (2004) The Nesting Ecology of the Allen Cays Rock Iguana, Cyclura Cychlura Inornata, in the Bahamas. Herpetological Monographs, 18(1): 1 - 36.
6. Sangue Freddo Net (June, 2006)
   http://www.sanguefreddo.net/SFNpro/modules.php?op=modload&name=News&file=article&sid=81&mode=thread&order=0&thold=0