Overview

Distribution

Crested geckos are endemic to the islands of Grand Terre (Provence Sud), and the Isle of Pines, New Caledonia. There are unconfirmed reports of these geckos from Kôtomo Island, New Caledonia.

Biogeographic Regions: australian (Native )

Other Geographic Terms: island endemic

  • De Vosjoli, P. 2003. Rhacodactylus: The Complete Guide to their Selection and care. Vista, California: Advanced Visions Inc..
  • Whitaker, A., R. Sadlier. 2011. "Rhacodactylus ciliatus" (On-line). The IUCN Red List of Threatened Species. Accessed February 27, 2013 at http://www.iucnredlist.org/details/176173/0.
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Range Description

This species is endemic to Province Sud, New Caledonia. It occurs in Grande Terre, and Ile des Pins. On Grande Terre there are only four known localities widely scattered across the southern half of the island (Canala to Rivière Bleue). It is possible that this species occurs in intervening forested areas. It occurs at elevations between 150 m and 1,000 m. The extent of occurrence is approximately 1,600 km².

[Extent of occurrence was based on a crude measure of overall length times width of the most distant known locations (a rough measure of the line around the points), except for very widespread species where the published areas of the islands were taken.]

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Continent: Oceania
Distribution: EC New Caledonia  
Type locality: New Caledonia.
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Physical Description

Morphology

Crested geckos have a relatively large, triangular head, with two large eyes and two relatively large ear openings on either side of the head. Very fine light tan, peach, or reddish brown-colored granular scales cover their long bodies. They have moderately thick, prehensile tails. The back typically has a pattern of lateral, darker stripes. Thin, continuous, calcareous crest, project along either side of the back and also above the eyes and portions of the limbs. Above the eyes, these crests seem to serve primarily to keep dust and other particles out, but it is unknown what purpose is served by the dorsal and limb crests; they may be used in discriminating between potential mates. There are three color morphs that appear in wild crested geckos: patternless, tiger, and white-fringed. Patternless crested geckos are more or less solid in color, ranging from yellow, green, brown, red, to gray, and have very faint or no pattern present on the back. Tiger crested geckos have a light colored background with deep, dark, contrasting stripes and a patterned belly. White-fringed crested geckos are characterized by white or yellow coloration on all or a portion of the calcareous crest. In addition to these three patterns, there are many other variations that are distinct in captive bred individuals but are not found in the wild.

Crested geckos have four limbs, each ending in four fingers; at the bottom of each finger is a network of hairs (setae) which allow them to walk on very smooth vertical surfaces. These pads are especially important in tree climbing. Crested geckos also have a prehensile tail with setae at the tip, adding extra support when hanging from tree branches or trying to regain balance; unlike many species, these geckos can not re-grow their tails if lost. Adult crested geckos typically average 20.3 centimeters in total length and 10.2-11.9 centimeteres snout-to-vent length (SVL). These geckos lack eyelids, though they do have a clear protective covering over each eye. They must lick their eyes with their tongues periodically in order to keep them clean and moist. Crested geckos have a small opening, covered in a tympanic membrane, on each side of side of the head, which acts as an ear.

Range mass: 30 to 35 g.

Average length: 20.3 cm.

Sexual Dimorphism: sexes alike

  • Badger, D., J. Netherton. 2002. Lizards: A Natural History of Some Uncommon Creatures - Extraordinary Chameleons, Iguanas, Geckos, and more. St. Paul, Minnesota: MBI Publishing Company.
  • Boulenger, G. 1883. On the Geckos of New Caledonia. Proceedings of the Zoological Society of London, 51/1: 116-139.
  • Jusufi, A., D. Goldman, S. Revzen, R. Full. 2008. Active Tails Enhance Arboreal Acrobatics in Geckos. Proceedings of the National Academy of Sciences of the United States of America, 105/11: 4215-4219.
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Ecology

Habitat

There are three distinct and disjunct populations of crested geckos: one on the Isle of Pines, and two on Grand Terre. The southeastern rainforests of Grand Terre, the main island of New Caledonia where crested geckos are primarily found, are divided by the highest peak on the island, Mont Paniė (1628 meters above sea level). This greatly influences climate and soil type in the region. High and low temperatures can range from 11.1-27.8°C, though temperatures typically range from 22.2-23.9°C. This area is tropical rainforest with precipitation levels potentially as high as 400 cm per year. They are most typically found at elevations from 150-1000 meters above sea level. Crested geckos spend daytime hours resting in thick vegetation near the forest floor, where it is cooler and less sunny. At night they spend much of their time foraging in shrubs and lower portions of the canopy, rarely traveling much higher than 3 m from the forest floor.

Range elevation: 150 to 1000 m.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: rainforest

  • Logan, L., G. Cole. 2001. New Caledonia. Footscray, Victoria, Australia: Lonely Planet Publications Pty Ltd..
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Habitat and Ecology

Habitat and Ecology
This species inhabits coastal forests, closed humid forests and montane forests. It is nocturnal and arboreal. It shelters by day in tree crevices and holes or amongst dense foliage, and forages at night in the canopy.

Systems
  • Terrestrial
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Trophic Strategy

Crested geckos are omnivores, feeding primarily on insects, nectar, and fruits, hunting and feeding at night. Calcium and Vitamin D3 are vital for the proper growth and development of crested geckos, especially for young individuals. Deficiencies can result in metabolic bone diseases, which can be fatal, so they have endolymphatic sacs on the roofs of their mouths for calcium storage.

Animal Foods: insects

Plant Foods: fruit; nectar; sap or other plant fluids

Primary Diet: carnivore (Insectivore ); herbivore (Frugivore , Nectarivore , Eats sap or other plant foods); omnivore

  • Cooper, T. 2000. Coorespondence Between Diet and Food Chemical Discriminations by Omnivorous Geckos (Rhacodactylus). Journal of Chemical Ecology, 26/3: 755-763.
  • McWilliams, D. 2005. Nutritional Research on Calcium Homeostasis in Lizards (with Recommendations). International Zoo Yearbook, 39/1: 69-77.
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Associations

Very little is known of the role that crested geckos have in their ecosystem. One reason for this is that, for more than a century, crested geckos were believed to be extinct. In 1994 they were rediscovered and most of the studies and observations carried out following their rediscovery were on captive bred individuals. Crested geckos are likely important in the distribution of pollen for various nectar and fruiting plants. These geckos have been found to host parasitic amoebas and protozoans.

Ecosystem Impact: pollinates

Commensal/Parasitic Species:

  • Bauer, A., R. Sadlier. 1993. Systematics, Biogeography, and Conservation of the Lizards of New Caledonia. Biodiversity Letters, 1: 107-122.
  • May, R. 2013. "Care Sheet: Rhacodactylus ciliatus" (On-line). D.D. Reptiles. Accessed February 27, 2013 at http://www.ddreptiles.net/caresheet_ciliatus.html.
  • Modrý, D., M. Jirků, M. Veselý. 2004. Two new species of Isospora (Apicomplexa: Eimeriidae) from geckoes of the genus Rhacodactylus (Sauria: Gekkonidae) endemic to New Caledonia. Folia Parasitologica, 51: 283-286. Accessed February 27, 2013 at http://folia.paru.cas.cz/pdfs/51_4_283_Modry.pdf.
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One of the main predators of crested geckos are little fire ants, which have been introduced to New Caldonia and will swarm and bite the geckos. Other predators include dogs, cats, rats, snakes, and other geckos, many of which are introduced species as well. Crested geckos exhibit caudal autotomy and can drop their tails if in danger from a predator. Vasoconstrictor mechanisms prevent the tail from bleeding and small fractures in the tail bone allow the tail to break off at predetermined segments. After being dropped, the tail will continue to move for 3-5 minutes, distracting the predator as the gecko escapes. These geckos can not re-grow their tails, which can cause them to become less agile.

Known Predators:

  • Pianka, E., S. Sweet. 2005. Integrative Biology of Sticky Feet in Geckos. BioEssays, 27/6: 647-652. Accessed April 13, 2012 at services.lib.mtu.edu:2982/doi/10.1002/bies.20237/pdf.
  • Seipp, R., F. Henkel. 2000. Rhacodactylus-Biology, Natural History & Husbandry. Franfurt am Main, Germany: Edition Chimaira.
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Life History and Behavior

Behavior

Crested geckos use a high pitched chirping sound that is primarily used to call for a mate and as a defense mechanism to frighten a predator in an attempt to escape. They also use visual cues; if startled, crested geckos have been known to rise up on their hind legs and open their mouths wide in a threatening posture, and mating involves jerky body motions from the male.

Crested geckos have specialized eyes for seeing in the dark. Like other gekkonid species, crested geckos have what has been referred to as Gehyra pupils; instead of having vertical, slit-shaped pupils with smooth edges, geckos have vertical, slit-shaped pupils with slightly lobed edges. They have color vision, as their retinas contain only cones. Nocturnal geckos such as these have larger apertures and cones, in addition to a shorter viewing length, than diurnal reptiles. This allows them to absorb as much light and see as much as possible in the dark.

Communication Channels: visual ; tactile ; acoustic

Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical

  • Roth, L., A. Kelber. 2004. Nocturnal Colour Vision in Geckos. Proceedings: Biological Sciences, 271/6: S485-S487.
  • Underwood, G. 1951. Pupil Shape in Certain Geckos. Copeia, 1951/3: 211-212.
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Life Cycle

Information regarding development in this species has not been gathered in the wild, but has been extensively recorded in captivity. It has been found that temperature is a determining factor on rate of development, offspring size, and sex. In particular, sex is not determined genetically but after egg laying, by environmental temperature. Evidence suggests that warmer incubation temperatures lead to higher proportions of males and colder incubation temperatures lead to higher proportions of females. It has also been observed that crested gecko eggs kept at higher temperatures during incubation develop faster than eggs kept at lower temperatures.

After hatching, young crested geckos will not eat for 3-5 days (until they shed their skins for the first time), using stored yolk remains for sustenance. After this period of time, hatchlings will begin searching for food such as nectar, fruits, and small insects.

Development - Life Cycle: temperature sex determination; indeterminate growth

  • Andrewartha, S., N. Mitchell, P. Frappell. 2010. Does Incubation Temperature Fluctuation Influence Hatchling Phenotypes in Reptiles? A Test Using Parathenogenetic Geckos. Physiological and Biochemical Zoology, 83/4: 597-607.
  • Gamble, T. 2010. A Review of Sex Determining Mechanisms in Geckos (Gekkota: Squamata). Sexual Development, 4/1-2: 88-103. Accessed February 27, 2013 at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2855288/.
  • Valenzuela, N. 2004. Temperature-dependent Sex Determination. Reptilian Incubation: Environment and Behaviour, 1: 211-227.
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Life Expectancy

Crested geckos are thought to be able to live for over 20 years in captivity, though there is some uncertainty; they have only recently been reintroduced to science and the pet trade (1994) after having been assumed extinct. No information regarding lifespan in the wild is currently available.

Range lifespan

Status: captivity:
10 to 20 years.

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Reproduction

Mating behaviors have yet to be observed in the wild. Captive males have been known to fight violently if forced into contact with each other, especially during breeding season, and so multiple breeding females are kept with one male. A male will approach a female with jerky movements and, if she is willing, she will remain still while he climbs on her back and bites her neck as copulation begins.

Mating System: polygynous

Males become sexually mature between 9-12 months of age and females typically become mature at 12 months at a weight of 30-35 gm. At 3-4 months old, an external hemipenal bulge becomes visible in males, located at the base of the tail near the vent. In contrast, females are flat at the base of their tails, with much smaller bulges. Females are capable of laying 2 eggs every 4-6 weeks and do so 30-40 days after copulation; they retain sperm and may lay up to 4 eggs before copulating again. Breeding and egg laying takes place 8-10 months of the year, with a shift to lower temperatures halting egg production. If this resting period does not occur, females may lay eggs year round and are at risk of suffering severe calcium deficiencies. Eggs can be as large as 11x24 mm and 1.2-2.8 gm, and hatch 60-150 days after being laid. Young are independent at hatching.

Breeding interval: Breeding may occur every 4-6 weeks.

Breeding season: Egg laying takes place 8-10 months of the year; it may occur year round if there is no cooling cycle.

Range number of offspring: 2 (low) .

Range gestation period: 90 to 190 days.

Average age at sexual or reproductive maturity (female): 1 years.

Range age at sexual or reproductive maturity (male): 9 to 12 months.

Key Reproductive Features: iteroparous ; year-round breeding ; sexual ; fertilization ; oviparous ; sperm-storing

Males exhibit no parental investment beyond fertilization. Females allocate nutrients to their eggs (moreso because of their small clutches) and lay their eggs in a hole a few inches deep, safe from predators, and within an appropriate proper temperature range and soil moisture, allowing for gas exchange through the egg membrane. After laying her eggs, the female does not provide any additional parental care to her developing offspring.

Parental Investment: female parental care ; pre-fertilization (Provisioning)

  • 2013. "Crested Gecko" (On-line). Biotropics. Accessed February 27, 2013 at http://www.biotropics.com/englisch/html/rhacodactylus_ciliatus.html.
  • Andrewartha, S., N. Mitchell, P. Frappell. 2010. Does Incubation Temperature Fluctuation Influence Hatchling Phenotypes in Reptiles? A Test Using Parathenogenetic Geckos. Physiological and Biochemical Zoology, 83/4: 597-607.
  • Christian, K., G. Bedford. 1993. High Reproductive Expenditure Per Progeny in Geckos Relative to Other Lizards. Journal of Herpetology, 27/3: 351-354.
  • De Vosjoli, P. 2003. Rhacodactylus: The Complete Guide to their Selection and care. Vista, California: Advanced Visions Inc..
  • Valenzuela, N. 2004. Temperature-dependent Sex Determination. Reptilian Incubation: Environment and Behaviour, 1: 211-227.
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Conservation

Conservation Status

Little is known about crested geckos in their natural environments, and even less in known about the impact of human activities on their populations. Slash and burn agriculture, deforestation, and mining (nickel, cobalt and chromium), as well as the introduction of non-native species are all believed to be threats to crested geckos and they are classified by The IUCN Red List as "Vulnerable", with a downward population trend. The primary indigenous conservation organization on New Caledonia, the Association pour la Savvegarde de la Nature NėoCalėdonienne (ASNNC) is currently working with the government to protect more land and habitat and raise awareness about the reptilian fauna of the islands. The other organization working to protect this environment is the Center of Initiation of the New Caledonia Environment. The hope is that laws will eventually be passed to protect the terrestrial reptilian fauna there.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

  • Gamble, T., A. Bauer, T. Jackman, E. Greenbaum. 2008. Out of the Blue: A Novel, Trans-atlantic Clade of Geckos (gekkota, squamata). The Norweigian Acadeny of Science and Letters, 37/4: 355-366.
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IUCN Red List Assessment


Red List Category
VU
Vulnerable

Red List Criteria
B1ab(i,ii,iii,v)

Version
3.1

Year Assessed
2013

Assessor/s
Whitaker, A.H. & Sadlier, R.A.

Reviewer/s
Tognelli, M. & Cox, N.A.

Contributor/s

Justification
Rhacodactylus ciliatus is listed as Vulnerable because it has a restricted distribution and there is continuing decline in the extent and quality of its habitat. At least 50% of the range of this species is likely under threat. There is habitat fragmentation over part of the range but there are also relatively large continuous tracts of habitat.
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Population

Population
There are no quantitative data on population size or trends. It is presumed to have suffered a substantial reduction in population size and extent in the past through habitat loss associated with logging, wildfires and the clearance of low and mid-elevation forests for agriculture.

Population Trend
Decreasing
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Threats

Major Threats
The main threats to this species are the further loss or degradation of habitat from wildfires and clearance for agriculture, predation by rodents, and, at lower elevation sites, the impact of the introduced ant Wasmannia auropunctata (Jourdan et al. 2000, 2001). Habitat loss and fragmentation are the main threats on Ile des Pins. At all Grande Terre locations habitat degradation from introduced ungulates (deer and pigs) is also a problem. Illegal collection and trafficking of Rhacodactylus ciliatus is a risk at accessible locations.
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Management

Conservation Actions

Conservation Actions
Protected in Province Sud under Code de l'environnement de la Province Sud (Délibération No. 25-2009/APS, 20 March 2009). This species is present in Parc Provincial de la Rivière Bleue but it is not known to occur in any other protected areas. No active conservation management is currently being undertaken for this species.
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Relevance to Humans and Ecosystems

Benefits

There are no known adverse effects of crested geckos on humans.

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Crested geckos are a favorite in the pet trade because they are very docile and are easy to maintain. The wide availability of crested geckos may help to draw attention to the 41 regionally endemic species of reptiles present on New Caledonia and the importance of protecting them. An interest in preserving these habitats could then play some role in increasing wildlife research and conservation efforts on these islands.

Positive Impacts: pet trade ; research and education

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Wikipedia

Crested gecko

The crested gecko, New Caledonian crested gecko, Guichenot's giant gecko or eyelash gecko, Correlophus ciliatus, is a species of gecko native to southern New Caledonia. This species was thought extinct until it was rediscovered in 1994.[2] Along with several Rhacodactylus species, it is being considered for protected status by the Convention on the International Trade in Endangered Species of Wild Flora and Fauna. It is popular in the pet trade.

Taxonomy[edit]

The species was first described in 1866 as Correlophus ciliatus by the French zoologist Alphone Guichenot in an article entitled "Notice sur un nouveau genre de sauriens de la famille des geckotiens du Muséum de Paris" ("Notes on a new species of lizard in the gecko family") in the Mémoires de la Société Scientifique Naturelle de Chérbourg. It was later renamed Rhacodactylus ciliatus. Recent phylogenetic analysis indicates that R. ciliatus and R. sarasinorum are not closely related to the other giant geckos, so these two species have been moved back to the genus Correlophus.[3]

The specific name, ciliatus, is Latin: Cilia means "fringe" or "eyelash" and refers to the crest of skin over the animal's eyes that resembles an eyelash.

Physical description[edit]

Orange color phase

The crested gecko has hair-like projections found above the eyes, resembling eyelashes. It has a wedge-shaped head and a crest that runs from each eye to the tail. Crested geckos do not have eyelids and so they use their long tongues to moisten their eyes and remove debris. The toes and the tip of the semi-prehensile tail are covered in small hairs called setae. Each seta is divided into hundreds of smaller (approximately 200 nanometres in diameter) hairs called spatulae. It is believed these structures exploit the weak van der Waals force to help the gecko climb on most solid surfaces. The toes have small claws which aid in climbing surfaces to which their toes cannot cling. They possess a prehensile tail which they use to assist in climbing. The tail can be shed as a deterrent to predators. Unlike some other geckos, once they lose their tail it will not grow back; however, this is not as harmful to the gecko as it is to others, such as the Leopard gecko.[2]

The crested gecko has many naturally occurring color groups, some of which include: grey, brown, red, orange, and yellow of various shades. They have variable markings, which include spots, straight stripes, and tiger-like stripes. The colors are brighter and more prominent at night.

The crested gecko has distinct structural morphs in head size and crest abundancy. Geckos with a head length less than 1.3 times its width are considered "crowned" crested geckos. They can vary in the amount and size of the crests; some have crests that extend to the base of the tail and some lack crests on one side of their body.

Geographic distribution[edit]

The crested gecko is endemic to South Province, New Caledonia. There are three disjunct populations, one found on the Isle of Pines and surrounding islets, and there are two populations found on the main island of Grande Terre. One population is around the Blue River, which is a protected provincial park, and the other is further north, just south of Mount Dzumac.

A female New Caledonian crested gecko

Ecology and behavior[edit]

Jumping crested gecko

The crested gecko has no eyelids; a transparent scale, or spectacle, keeps its eyes moist and it uses its tongue to clear away debris, this is called a brill. Like all Rhacodactylus and related geckos, it has webbing on its legs and digits. They are a mostly arboreal species, preferring to inhabit the canopy of the New Caledonian rainforests, and because of this they can jump considerably well. They are primarily nocturnal, and will generally spend the daylight hours sleeping in a secure spot in a tree. Unlike most arboreal geckos however, its not as strong a climber as those of the Tokay Gecko species, its foot pads are less able to grip than its cousins.

The crested gecko, unlike the closely related gargoyle gecko (Rhacodactylus auriculatus), will not regrow its tail once lost.[2] The cells around the base of the tail are brittle, allowing the tail to break away when threatened or caught by a predator. The capillaries to the tail will close almost instantly so there is little to no blood loss. The tails will move independently of the body for 2–5 minutes. The loss of their tail is not problematic, and most adults in the wild do not have their tails.

Unlike most species of gecko, this species is an omnivore, also considered frugivorous, feeding on a variety of insects and fruit.[2] In captivity, they should be fed a commercially-prepared, fruit-based diet with live feeder insects as a supplement. An unbalanced diet can quickly lead to Metabolic Bone Disease (MBD).[4]

Captivity[edit]

Though the export of wild crested geckos is now prohibited, biologists exported several specimens for breeding and study before New Caledonia stopped issuing permits to export the species.[2] From these specimens, different breeding lines were established both in Europe and the United States.[2] The crested gecko is now one of the most widely kept and bred species of gecko in the world.[2]

These geckos can be very long lived. While they have not been kept in captivity long enough for a definitive life span determination, they have been kept for 15–20 years or more. They can be kept healthy on specially prepared diets with sufficient calcium and other nutrients.[5][citation needed]

Reproduction[edit]

Crested geckos mating

Little is known about the wild reproductive behavior of crested geckos, but in captivity they breed readily, with the female laying two eggs which hatch 60–150 days after they are laid. Eggs are generally laid at four week intervals as long as the fat and calcium reserves of the female are still at healthy levels. Crested geckos have two small sacs for calcium on the roof of their mouths. If an egg laying female does not have enough calcium her sac will be depleted, and she can suffer from calcium deficiency. This can lead to a calcium crash where the female appears shaky or wobbly, lethargic, has a lack of appetite, and can even result in death.[2] Eggs laid by a female whose calcium reserves are low occasionally exhibit signs of metabolic bone disease, such as an under bite, or a kinked or wavy tail.

It is undetermined whether heat plays a role in determining the sex of the embryo, as it can with other gecko species. Newly hatched crested geckos will generally not eat until after they shed their skin for the first time, relying on the remains of their yolk sack for nutrition.[2]

A female crested only has to mate with a male once in order to lay 2 eggs every 4–6 weeks for upwards of 8–10 months. Retaining of sperm ensures the eggs the female lays remain fertile throughout her breeding cycle. After those 8–10 months, females in the wild go through a "cooling" cycle, usually prompted by slight temperature changes in winter, which help her regain lost nutrients from egg-laying. In captivity this cooling cycle must be controlled or the female will lay eggs continuously, even to death.

Status in the wild[edit]

Long believed extinct, the species was rediscovered in 1994 after a tropical storm.[2] It is currently being assessed for CITES protection and vulnerable status. The biggest single threat to the wild population appears to be the introduction of the little fire ant (Wassmania auropunctata) to New Caledonia.[2] The ants prey on the geckos, stinging and attacking in great numbers and also compete with the geckos for food by preying on arthropods.

See also[edit]

References[edit]

  1. ^ Whitaker, A.H. & Sadlier, R.A. (2011). Rhacodactylus ciliatus. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. Downloaded on 23 May 2012.
  2. ^ a b c d e f g h i j k De Vosjoli, Phillipe; Repashy, Allen; Fast, Frank (2003), Rhacodactylus: The Complete Guide to their Selection and Care, Advanced Vivarium Inc, ISBN 978-0-9742971-0-1 
  3. ^ Aaron M. Bauer, Todd R. Jackman, Ross A. Sadlier and Anthony H. Whitaker (2012). "Revision of the giant geckos of New Caledonia (Reptilia: Diplodactylidae: Rhacodactylus)". Zootaxa (3404): 1–52. 
  4. ^ http://jbscresties.com/basiccare.html
  5. ^ Reptile, Pangea. "Crested Gecko Care Sheet". Retrieved 2013-01-21. 
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