New Caledonian giant gecko

About the species

The leachie, as keepers call it after the scientific name, is the largest gecko in the world today. Animals from the main island of Grande Terre can reach 36-43 cm including the tail and weigh up to 500 g, while the animals from the small islands around the Isle of Pines are smaller, typically 23-30 cm and 150-300 g. The body is heavy, the head broad, and the skin hangs in loose folds along the flanks. The toes are broad with webbing between them, and the lamellae beneath give a secure grip on both bark and glass. The eyes have vertical pupils and no eyelids, so the gecko keeps them clean with its tongue.

The colours are pure camouflage: grey, brownish green or olive green with paler spots and marbling, so the animal almost disappears against a moss-covered trunk. Many adults have lost the original tail and have a short, lumpy replacement. Three subspecies used to be distinguished, but recent genetic studies do not support the division. Instead the animals are kept and sold as locality forms, named after the island or area they come from.

The species was described by Cuvier in 1829 and is related to the crested gecko, but is a completely different animal to keep. It grows slowly and is not fully grown until three to five years of age. It is calm and can be accustomed to handling, but it bites if it becomes frightened, and a bite from a large animal hurts.

The figures for size and lifespan vary between sources, partly because the locality forms are so different. The figures in the fact box cover both the small island forms and the large animals from the main island.

Care

The enclosure

An adult needs a tall enclosure of at least 60 × 45 × 90 cm (length × width × height). Many care guides settle for 45 × 45 × 60 cm, but that is cramped for an animal of 40 cm and several hundred grams, and a spacious home makes for a calmer animal. A pair should have at least 90 × 45 × 90 cm.

Hatchlings and juveniles do best in a faunarium or a small, densely planted enclosure, where they feel safe and easily find food and water. They are moved up as they grow. Kitchen roll is a good substrate for the smallest, because the droppings are easy to see and remove.

Furnish with sturdy branches at different angles and heights, large cork tubes and cork bark and dense foliage, preferably live plants such as pothos and rubber plant. The animal must be able to hide high up. A box with damp sphagnum provides a humid hide and a laying site. A moisture-retaining mix of coconut fibre and soil without fertiliser is suitable as substrate, preferably as a bioactive substrate. Ensure good ventilation, preferably both at the bottom and at the top.

Temperature

The leachie does best at ordinary room temperature. By day 22-27 °C is suitable, and at night it may drop to 18-22 °C. The nightly cooling corresponds to conditions in the wild and keeps the animal active. If the room stays above about 20 °C, many manage entirely without extra heat.

Heat is the greatest danger. If the temperature stays above 28-29 °C for long, the animal becomes stressed and can come to harm. Some keepers provide a small warm spot of up to about 30 °C, while others advise against heat lamps altogether, so the fact box gives no hotspot. If it gets too cold in winter, a weak heat mat on the side or a low-wattage heat bulb controlled by a thermostat can provide what is missing. Always measure with a digital thermometer.

Humidity and water

The humidity should be 50-80%. Mist the enclosure every evening so that the humidity rises to 70-80%, and let it fall again during the day so the substrate and branches have time to dry out. Constantly wet conditions cause mould and skin problems. Some breeders mist only one half, so the animal can choose for itself.

The gecko drinks droplets from leaves and glass, but also provide a heavy, stable water dish, and change the water at least every other day and at once if it is dirty. A hygrometer in the middle of the enclosure shows whether the rhythm is holding.

Lighting and UVB

The species is nocturnal and can live without UVB when it gets vitamin D3 through its food. Many keepers use light only for the sake of the plants. If a low-level UVB tube is offered, however, the animals often use it. If you choose UVB, keep it weak, as for shade-dwelling animals (Ferguson zone 1), and make sure the animal can always retreat into shade.

Keep the light on for 10-12 hours a day, preferably controlled by a timer, and keep it dark at night. Avoid strong spotlights and coloured night lights.

Feeding

The staple diet is a prepared powdered diet for fruit-eating geckos, mixed with water into a thick paste and served in a dish, preferably on a holder high up. Pangea and Repashy are widespread brands. Adults get the paste 2-3 times a week, juveniles more often, and leftovers are removed after a day.

In addition, give live insects one or more times a week: dubia roaches, crickets and locusts, with waxworms and silkworms as a treat. The insects must not be wider than the distance between the animal's eyes and must be dusted with calcium with vitamin D3. Some keepers give a small pinkie once a month, especially to breeding females, but it is not necessary. Ripe fruit such as mango, pear and fig can be given as a treat in small amounts.

Hatchlings begin to eat three to five days after hatching and get powdered diet and small crickets 3-4 times a week. Females may go off their food just before laying and then eat extra afterwards. Weigh the animals regularly, so you can follow whether they are gaining weight.

Behaviour and handling

The leachie is calm and can become tame, but it is not a pet to be handled every day. It can bite when frightened, and a bite from a large animal hurts and can bleed. Handle it calmly, low down and for short periods, and give new animals a couple of weeks to settle in. Preferably leave hatchlings in peace for the first couple of months. Never grab the tail.

By day it sleeps in a hide. It can growl, bark and click when defending itself or when displeased. As a rule, keep the animals singly. A male and a female can sometimes live together for years if there is plenty of space and many hides, but even a well-functioning pair can suddenly begin to fight, so be ready to separate them. Two males must never be kept together, and attempts with one male and two females most often end in fights.

Breeding

Sexual maturity and sexing

Males have a distinct bulge at the base of the tail and a V-shaped row of pores in front of the vent, so the sex can be recognised at a fairly young age. The animals grow slowly and should not be used for breeding until they are at least three years old, and often four to five years pass. Females from the islands should weigh at least about 120 g and females from the main island over 180 g. A female that is too young or too light risks being drained of calcium or having eggs that become stuck.

Mating

Breeding follows the seasons. Give the animals a cool period from November to February at temperatures at the low end of the normal range, around 21-23 °C, and then raise the temperature a couple of degrees in February and March. This kick-starts the season.

Preferably introduce the animals through a mesh for the first few days, for example by placing the male in a small mesh cage inside the female's enclosure. Pairs that suit each other often rest close together, while incompatible animals bark and try to attack through the mesh. The male bites the female on the neck during mating, and minor scrapes are common. Separate them in case of serious injuries or signs of persistent aggression. Some keepers let the pair live together throughout the season, others put the male in only for mating.

Egg-laying and clutches

The female usually lays her first clutch about 30 days after mating, and a clutch is always two eggs. New clutches then follow at intervals of about five weeks. The number varies greatly: one to six clutches per season have been seen, and two to three is normal, although a few females lay far more.

Provide a laying box with damp sphagnum or coconut fibre, otherwise the female buries the eggs in the substrate. Give her extra calcium and food during the season, and stop breeding if she loses weight. Single females occasionally lay eggs without a male, and there are even reports of such eggs having hatched.

Incubation

Carefully pick up the eggs without turning them, and place them half-buried in damp vermiculite or perlite in a box with small air holes. Put the box in an incubator or somewhere with a stable temperature between 22 and 28 °C.

Temperature governs the duration: at high temperature the eggs hatch after about 45 days, at low temperature it can take up to 150 days. Warm incubation also produces more males, and cool more females, but there are no reliable threshold values for the species. Eggs that collapse and turn yellow or mouldy are usually not fertilised, but leave them until you are sure.

Rearing the young

The young look like small versions of the adults, and their size depends on the locality form. Move them individually to a small faunarium or plastic box with air holes, kitchen roll as substrate, a hide and a small water dish. Keep them apart, so they do not stress or bite each other.

The young begin to eat after three to five days. Give them powdered diet and small crickets 3-4 times a week, and change the water every other day. Many young are hesitant about insects for the first few months and live mostly on the paste. They grow slowly compared with other geckos and are moved to larger housing as they grow.

Health and common mistakes

The leachie is hardy, but certain problems recur:

• Heat above 28-29 °C, for example in an enclosure by a window in summer. This causes stress and loss of appetite.
• Too little calcium and vitamin D3 in young animals and breeding females, causing soft bones, bent limbs and tremors. Use a good prepared diet, and dust the insects.
• A constantly wet substrate and poor ventilation, which cause fungus and skin problems.
• Stuck shed on the toes and tail tip. Provide a humid hide, and gently loosen the remains with lukewarm water.
• Obesity in animals that get too much food and too little exercise in an enclosure that is too small.
• Parasites and infections in newly acquired animals. Keep new animals separate, and have a faecal sample examined.
• Bite wounds after mating or fights, which must be kept clean and monitored.

A healthy animal has clear eyes, a plump tail base and a good grip. Seek a vet with experience in reptiles if the gecko loses weight, does not eat for several weeks, develops swellings or seems limp.