Crested gecko

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.[5]

The specific name, ciliatus, is Latin, from cilia ("fringe" or "eyelashes") and refers to the crest of skin over the animal's eyes that resembles eyelashes.

This captive crested gecko has a tricolor extreme harlequin pattern that is not found in the wild.

Crested geckos are among the largest gecko species and typically range from 6–10 inches (15–25 cm) in length, including 4–6 inches (10–15 cm) of tail length.[3] Among the most distinctive features of these geckos are the hair-like projections found above the eyes, which greatly resemble eyelashes. Crested geckos also have two rows of spines that run from the sides of their wedge-shaped head to the base of their 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 semi-prehensile tail which they use to assist in climbing. The tail can be dropped (via caudal autotomy) 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 in other species, such as the leopard gecko, which store fat reserves in their tails.[6] In fact, most adults in the wild lack tails.[4]

The crested gecko has many naturally occurring color groups, including grey, brown, red, orange, and yellow of various shades. They have three color morphs in the wild, which include pattern-less, white-fringed, and tiger. Breeders of the species have achieved many other patterns such as the extreme harlequin pattern that are not observed in the wild.[7]

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

A tailless New Caledonian crested gecko

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.

Jumping crested gecko

A captive crested gecko cleaning its eyes.

Crested geckos do not have eyelids. Instead, a transparent scale, or spectacle, keeps each eye moist, and the geckos use their tongues to clear away debris. Like the closely related Rhacodactylus geckos, crested geckos have webbed 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're also crepuscular, and will generally spend the daylight hours sleeping in secure spots in high branches.[1] Crested geckos are, however, less strong climbers than tokay gecko.

Crested geckos shed their skin up to once a week when young. When fully grown, the process only occurs once every one or two months.[8]

The crested gecko – unlike the closely related gargoyle gecko (Rhacodactylus auriculatus) – will not regrow its tail once lost.[6] 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 fruit, nectar, pollen, and a variety of insects.[6][9] In captivity, they should be fed a commercially prepared, fruit-based diet with live feeder insects as a supplement. An unbalanced diet containing insufficient calcium can quickly lead to metabolic bone disease (MBD).

Juvenile female crested gecko

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. From these specimens, different breeding lines were established, both in Europe and the United States. The crested gecko is now one of the most widely-kept and bred species of gecko in the world.[6]

Baby crested gecko eating a cricket

These geckos can be very long-lived. While they have not been kept in captivity long enough for a definitive life span to be determined, they have been kept for 15–20 years or more.[8] They can be kept healthy on specially prepared powdered fruit diets with sufficient calcium, or a variety of insects dusted with calcium or multivitamin supplements.[10]

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.[6] Eggs laid by a female whose calcium reserves are low occasionally exhibit signs of congenital metabolic bone disease, such as an underbite and/or a kinked or wavy tail.

It is currently unknown 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 have shed and eaten their skin for the first time, relying on the remains of their yolk sack for nutrition.[6]

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. Sperm retention ensures that the eggs the female lays will remain fertile throughout her breeding cycle. If the female does not mate with a male, she will lay unfertilized eggs.[11] After those 8–10 months, females in the wild go through a "cooling" cycle, usually prompted by slight temperature and daylight changes over the winter season. During this time, the females are able to regain the body mass and nutrients they lost during egg-laying. This cooling cycle must be implemented in captivity or females will lay eggs continuously, resulting in calcium depletion, poor health, and even death.

Although there is no confirmed cases of asexual reproduction in crested geckos, there has been claims of females laying eggs with no sexual activity with a male.

Long believed extinct, the species was rediscovered in 1994 after a tropical storm.[4] It is currently being assessed for CITES protection and vulnerable status.[12] The biggest single threat to the wild population appears to be the introduction of the little fire ant (Wassmania auropunctata) to New Caledonia.[6] The ants prey on the geckos, stinging and attacking in great numbers, and they also compete with the geckos for food by preying on arthropods. Other threats to the wild population include habitat damage from wildfires, rodent predation, and habitat degradation from introduced deer and pigs.[13]

Wikimedia Commons has media related to Correlophus ciliatus.

• Bauer, Aaron M. & Sadlier, Ross A. 2000 The Herpetofauna of New Caledonia. Society for the Study of Amphibians and Reptiles. ISBN 0-916984-55-9
• Crested Gecko Care Sheet REPTILES Magazine

Wikispecies has information related to Rhacodactylus ciliatus.