geckodan
Very Well-Known Member
Hi Guys, I had submitted this article to Reptiles Australia but in its current form it is considered too controversial to publish. Rather than save it to disk, never to be seen again, someone may as well get some benefit from it.
The Ring Tailed Gecko (Cyrtodactylus louisiadensis)
The Ring tailed Gecko is one of Australias most spectacular geckoes with an average adult SVL (snout-vent length) of 16cm and a TL (total length) of 34 cm. A typical adult specimen of SVL 15 cm will weigh on average 15 -20 grams.
This places the Ring Tail Gecko as one of Australia’s largest geckoes (arguably the largest based on total length). It is a spectacularly banded, active, voracious gecko. Although slender, these geckoes are solidly built, strong and aggressive.
Taxonomically, Cyrtodactylus louisiadensis, has been caught up in a bit of a renaming nightmare and as a result most references to C.louisiadensis overseas differ significantly in colour pattern from those maintained in collections in Australia. Recent reclassification reveals that references to C.louisiadensis overseas almost always refer to Cyrtodactylus irianjayensis originating from populations in New Guinea and the Solomon Islands. Morphologically the two species differ quite obviously with C.irianjayensis having ragged edges to its body stripes and C.louisiadensis having smooth edged stripes. The original type species description was based on an individual from Tagula Island, off the southern coast of New Guinea, not an Australian specimen so it is uncertain which species was actually looked at.
There are no recognised subspecies of Cyrtodactylus louisiadensis.
Within the Australian form, there are two colour morphs described. The commonly occurring form (in the wild and in captivity) is identified by having 6-7 body bands and 12-14 tail bands. Its tail is held in an upwards curve. This form occurs throughout the Australian range with variations in actual colour depending on locality.
The “rainforest” form from Iron Range is described as having generally 4 body bands and 7 tail bands. Its patterning is described as being less discrete and fading over the sides of the body. It carries its tail in a laterally orientated coil (overseas hatchlings do this but do not match the banding of this form). This description has always been confusing to me. I have no concerns with a third colour morph existing but for it to be so variable compared to the others and hold its tail differently has never made much sense to me. I had not until recently ever seen a photograph of this form. In Cogger 1975, a picture of a Cyrtodactylus louisiadensis from “Cape York” is provided. This individual bears no resemblance whatsoever to any louisiadensis I have ever seen but does match the description of the “Iron Range” form given in Wilson and Knowles 1988. The problem is that this specimen in Cogger’s photograph is indistinguishable from Cyrtodactylus intermedius of Thailand and India. This leaves me with three possible theories.
1. Cogger’s original picture was in arrears (and actually is a picture of C.intermedius from Thailand) and may be why it was not used in subsequent editions. Wilson and Knowles description was then based on Cogger’s picture and not on an actual specimen and has therefore reinforced the urban myth of the “Iron Range” form.
2. Wilson and Knowles description was based on a specimen or photograph other than Cogger’s picture and is a true variant of Cyrtodactylus louisiadensis.
3. The “Iron Range” form is a true entity in its own right and is possibly an extralimital population of C. intermedius or C.irianjayensis
Hopefully , I have tweaked some interest to reveal the true nature of this form.
The hatchlings are patterned similarly to adults but the patterning is brighter and more contrasting. In newly hatched juveniles, the bands at the front of the body are alternating brown and tan becoming black and white over the hind limbs and tail and usually finishing with a white tail tip. Small vertical white marks are found on the lips. The average SVL of a hatchling is 43mm and an average TL is 85mm.
Distribution and Habitat – Cyrtodactylus is a large genus extending from the western Pacific to Southern Europe. There is only one Australian species and an undescribed species from Christmas Island (an Australian territory) . Cyrtodactylus louisiadensis is found in North Eastern Queensland and as described before also occurs in New Guinea and the Solomon Islands. Within Australia there are two well recognised forms – a semi-arboreal form from isolated areas of thick coastal rainforest and a woodland, vine thicket and rock and cave inhabiting form extending from the coast to the harsher, drier inland sandstone country. This species forages on the ground, amongst foliage and vines, on tree trunks and logs and amongst rock fissures and boulders (non –vertical). It may also be found in association with farms and settled areas adjacent ideal habitat. This is a predominantly nocturnal species. The majority of individuals in captivity in this country originate from the non-rainforest form.
Sexing – Adult males are easily distinguished due to the prescence of significant hemipenal bulges and large hemipenal spur clusters (comprising 3-4 enlarged scales (may be asymmetrical) up to twice the size of adjacent scales). They also possess a row of at least 20 pores consisting of a variable number of both preanal pores and femoral pores separated by a series of enlarged but imperforate scales. Adult females have some enlargement in the hemipenal area but it is always less developed and rarely has a central depression. Hemipenal spur clusters are also smaller (spurs usually no more than 50% larger than adjacent scales). Preanal (and femoral) pores are usually absent but if present are not swollen and tan in colour as in males. Some adults show nocturnal colour dimorphism with males generally appearing paler (and more contrasting) in colour. I am not sure if this is a mood, dominance or random thing. It has been suggested by authors working with this species overseas that this dimorphism may also exist in juveniles and may be used as an aid in sexing them. I have not found this to be reliable in my specimens but long term studies have not been undertaken and this may be a feature of C.irianjayensis not C.louisiadensis..
Juveniles can be sexed reliably at 8-12 months of age with good feeding (once they have attained 60-80% of adult SVL). In some young males, preanal pore development may be visible at 50% of adult SVL.
Feeding – The Ring Tail gecko is an aggressive feeder, often launching itself 20 cm or more through the air to catch food items climbing up walls or attempting to flee. In the wild it feeds predominantly on large insects but it is also recorded as feeding on small frogs and other geckoes. In captivity, they will feed on any large insect (crickets, locusts, cockroaches, moths) and may also accept pink mice. It had intrigued me as too what calcium supply was relied on in the wild until I looked at a possible answer in some literature on Uroplatus geckoes. In the wild, these species consume small arboreal snails which would supply a significant calcium source. I have offered small (approximately 20% of the head size of the gecko) aquatic snails (from my fish tanks) and they are greedily consumed. Interestingly they are not chewed like a normal food item but are swallowed whole. I recommend that all other food items should be dusted with a suitable calcium supplement for at least two out of three feeds. In addition I supply a bowl of dry Calcium Carbonate powder or a granulated product like Bio-Cal (Australian Pigeon Company). Adults should be fed every 3-7 days during the warmer months and every 7-14 days during the colder moths although some adults will stop feeding during these cooler periods. Juveniles should be fed every 2-4 days throughout the year. Food item size for adults can be up to 80% of head size and up to 60% of head size in juveniles.
Housing
This species is equally at home in a terrestrial or arboreal environment and therefore its enclosure should be designed to cater for both behaviours. Cyrtodactylus lack adhesive lamellae on their toes and therefore have some difficulties with smooth surfaces such as glass. They do however have sharp claws that enable them to readily climb any other surfaces (this includes silicon remnants in the corners of fish tanks). Juveniles (due to their smaller size) can gain enough of a foothold to climb the walls of plastic containers. This species is not particularly aggressive and can be housed in groups or with other similar sized species. They are an active species and you should allow at least 30cm3 per individual. Within this space, they will often congregate in communal hide sites but usually forage individually. I have maintained this species as pairs or in groups of up to 6 individuals (1 male and 5 females). Only 1 male should be housed per enclosure. They do not fight viciously but do intimidate each other to the detriment of both individuals. I have successfully kept this species with Leaf tail gecko species (Saltuarius sp. and Platurus sp.).
Considering their natural habitat and distribution , they should be expected to be tolerant of high temperatures but in captivity this is not the case. I have found this species to be a little more tolerant than Leaf tail geckoes but it certainly has a sensitivity to temperature extremes. During winter periods , the temperature should be maintained between 20-25 o C. Additional heat can be supplied via a small wattage globe, heat tape or adequate increases above ambient temperature may be achieved from the provision of a UVB fluorescent light. At excessively low temperatures, this species becomes sluggish and will not feed. During summer, an ambient temperature of 27-30o C is recommended. I have encountered fatalities in this species when daytime temperatures have exceeded 34oC. In high temperatures, good ventilation is essential and individuals are at most risk in large plastic containers or in enclosures with fully enclosed glass or Perspex fronts. Using 8mm mesh for the front of all enclosures for this species can be helpful. It must be assumed that this tropical species avoids temperature extremes in its natural habitat by retreating to deep cavities in rocks and logs or seeking shelter in the depths of the rainforest.
Information provided in overseas texts often insists that in order to achieve any results with this species that it must be housed in high humidity environments. I have found that this is not the case with captive animals in my collection. In fact, most individuals in my collection actively seek out dry hide sites and spend little time in moist hides when they were provided. I have not experienced issues with dehydration or difficulties in shedding as recorded in overseas literature. I feel the primary reason for this is that the majority of Australian specimens originate from the inland populations in the drier part of this species range, an area dominated by large sandstone escarpments but it may simply be that C.irianjayensis has greater humidity needs than C. louisiadensis..
Appropriate UVB lighting is important for this species (minimum 5% UVB). Dietary calcium alone appears insufficient to provide prolific egg laying females with sufficient calcium for egg production. This is because this species produced hard shelled eggs. If only one or two clutches of eggs are laid, females cope well and show no evidence of ill health. Multiples clutches may result in a female showing signs consistent with hypocalcaemia (broken limbs, rubbery bones, seizures, egg binding). Provision of quality UVB lighting for at least 8-10 hours per day during the breeding season seems to prevent this. Whether or not UVB provision has a significant impact on juvenile development is uncertain as I have raised them successfully with and without UVB.
Suitable substrates for this species includes leaf litter, sand or a mixture of sand and coir peat. An area of deeper sand under a hide is useful for breeding purposes. Enclosure furniture should provide ground level hides (large upturned saucers, large bark pieces, sections of hollow logs) and climbing structures (vines, branches, rough textured walls).
Reproductive Behaviour
In the wild, breeding records for this species indicate that breeding is opportunistic. Most breedings are noted from September to March but personal communications with local herpetologists in North Queensland indicate that gravid females are not unusual in the period April to August.
In captivity, this species breeds mainly during the period October to April with less frequent clutches in the remainder of the year. I have observed apparent courtship or pre mating behaviour involving licking and biting over the shoulder and neck area but I have not observe mating which presumably takes place within the hides provided.
Juveniles of this species grow rapidly and can attain up to 70-80% of adult SVL in 12-18 months. At this size they are capable of reproduction.
Individuals may be maintained together throughout the year. I do not separate my stock because of the possibility of out-of-season clutches being laid. Heavily producing females may be rested however. Reintroduction to the male after separation rarely poses any problem beyond some initial over amorous intentions. Cooling can be utilised but I have not found it necessary as my animals are exposed to reduced natural ambient temperature within the room. I have not observed matings and therefore the period from mating to egg laying is difficult to determine. The first eggs laid by females that have been separated is generally 5-7 weeks after re-introduction. Gravid females increase moderately in abdominal bulk and the eggs may be seen easily through the abdominal wall skin.
Cytrtodactylus is somewhat unique amongst Australian geckoes (in addition to Heteronotia, Christinus, Nactus, Lepidodactylus, Hemidactylus and Gehyra sp.) in laying calcareous shelled eggs (not soft shelled). This feature places them in the subfamily Gekkonidae (the majority of Australian geckoes are in the subfamily Diplodactylinidae). Two eggs are laid per clutch (occasionally just 1 egg). The eggs are almost completely round and measure on average approximately 10-12 mm in diameter.
When freshly laid ,the eggs are for a short period partially soft and somewhat sticky and as a result it is not unusual for the eggs to be dented on the bottom from the substrate below and have pieces of substrate stuck to them. Do not try to remove stuck substrate as it will invariably pull out a plug of shell with it. Egg laying sites used by this species are variable. One would expect that this species should accept of semi moist containers as you would for every other species of gecko. This is not the norm and is likely to lead to disappointment as they invariably ignore them and lay in less appropriate sites if other sites are not available. The majority of eggs laid by my females are laid in a mound of dry sand under a hide site or in a container of dry sand and dry crumbled coir peat (50:50 mix). If alternative laying sites are not provided, some females will utilise a shallow scrape in a corner under litter or sand. This usually results in the eggs sticking to the enclosure floor or wall where any attempt to remove them results in egg damage. If a female does lay in a moist container, the eggs will often become mouldy quite rapidly.
Laying hard shelled eggs places an enormous burden on a females calcium metabolism. A single prolific female may lay up to 5-6 cluches per year with an average interclutch interval of 36-63 days being recorded (some may wait up to 150 + days between clutches). If the calcium utilisation required for this egg laying exceeds the individuals calcium supply or metabolic processing then two problems can arise. Initially you may notice thin shelled eggs. These eggs may be so thin that they collapse under the weight of the female when backfilling sand after laying. If calcium is not corrected when this warning sign appears then more serious problems may arise. If these females continued to lay they may develop systemic signs of calcium deficiency. These females will present with a combination of signs including seizures, paralysis (particularly hind legs), fractured jaws and may have multiple fractured limbs (due to weak bones collapsing under the lizards own body weight). If noticed early, some of these may be saved by giving oral calcium liquid directly to the mouth hourly for 3-6 hours and placing them under appropriate UVB lighting. If this has happened post egg laying then the prognosis is reasonable. If the eggs are yet to be laid then calcium supplementation needs to be provided at least twice daily until the eggs are laid. The prognosis is poor for these individuals and 70% may die. Of the survivors 70% will be re-effected at the next clutch .
The eggs should be incubated in a relatively dry medium (water:vermiculite 1:3 by weight or 1:30 by volume). Negligible swelling (compared to soft shelled eggs) occurs during the incubation period. No significant changes occur in the egg to give an indication of fertility except early signs of blood vessels when candled in the first week or two. Later candling is less discrete in its appearance. Eggs should ideally be incubated at a temperature of 27-30oC. At this temperature, average incubation times are 90-160 days. At room temperature, incubation can be successful but incubation periods up to 270 days have been recorded. At times, incubation periods follow no logic. In one season I placed three eggs (a clutch of 1 and a clutch of 2) laid only a few hours apart into a communal incubation container. The first egg hatched at 90 days, the second at 110 days and the third at over 190 days despite all existing under the same incubation environment. I follow one basic rule with this species, never throw an egg of this species out unless it has obviously no chance of sustaining life . I only discard eggs that are broken, severely discoloured, smelly or wet. If normal looking eggs are opened up at a time period considered to be far in excess of usual timing, it is not unusual to find a fully formed, live juvenile.
It appears that developed unhatched juveniles enter a “dormant” state and remain that way until triggered to emerge. The trigger is unknown but other Cyrtodactylus species (and some chameleons) can be triggered to hatch by sudden wetting of the well advanced eggs (after 100 days incubation) by placing wet sphagnum moss over the eggs. I am yet to try this with our species.
Unlike other gecko species, hatching is not preceded by egg sweating. The hatchling basically just kicks or pushes a plug of shell out of the side of the egg and emerges. I usually remove hatchlings from the incubation container after 6 hours and due to the fact that the eggs are hard shelled I feel that a hatchling left in the container may potentially crack the remaining egg if attempting to escape. Hatchlings will accept small crickets soon after hatching. I have experienced case of metabolic bone disease with this species and this is associated with either poor calcium supply (either pre hatching parental deficiency or nutritional deficiency once hatched) or poor calcium metabolism (due to lack of UVB lighting). Juveniles of this species will grow well if a well supplement diet is provided but seem to do better if they are provided with good quality UVB lighting as well.
Status in Captivity – This species is currently maintained in small but stable numbers. It popularity is increasing and as such its demand has increased in recent years. It is however prohibited or restricted by licencing schedules in some states. It is expected that this species should live for 7-10 years with a productive period of about 5 years on average.
_________________
Dr Danny Brown
Private Breeder of Australian Lizards and Birds
Specialising in Geckoes/pygopods/skinks and Finches/softbills/waterfowl.
The Ring Tailed Gecko (Cyrtodactylus louisiadensis)
The Ring tailed Gecko is one of Australias most spectacular geckoes with an average adult SVL (snout-vent length) of 16cm and a TL (total length) of 34 cm. A typical adult specimen of SVL 15 cm will weigh on average 15 -20 grams.
This places the Ring Tail Gecko as one of Australia’s largest geckoes (arguably the largest based on total length). It is a spectacularly banded, active, voracious gecko. Although slender, these geckoes are solidly built, strong and aggressive.
Taxonomically, Cyrtodactylus louisiadensis, has been caught up in a bit of a renaming nightmare and as a result most references to C.louisiadensis overseas differ significantly in colour pattern from those maintained in collections in Australia. Recent reclassification reveals that references to C.louisiadensis overseas almost always refer to Cyrtodactylus irianjayensis originating from populations in New Guinea and the Solomon Islands. Morphologically the two species differ quite obviously with C.irianjayensis having ragged edges to its body stripes and C.louisiadensis having smooth edged stripes. The original type species description was based on an individual from Tagula Island, off the southern coast of New Guinea, not an Australian specimen so it is uncertain which species was actually looked at.
There are no recognised subspecies of Cyrtodactylus louisiadensis.
Within the Australian form, there are two colour morphs described. The commonly occurring form (in the wild and in captivity) is identified by having 6-7 body bands and 12-14 tail bands. Its tail is held in an upwards curve. This form occurs throughout the Australian range with variations in actual colour depending on locality.
The “rainforest” form from Iron Range is described as having generally 4 body bands and 7 tail bands. Its patterning is described as being less discrete and fading over the sides of the body. It carries its tail in a laterally orientated coil (overseas hatchlings do this but do not match the banding of this form). This description has always been confusing to me. I have no concerns with a third colour morph existing but for it to be so variable compared to the others and hold its tail differently has never made much sense to me. I had not until recently ever seen a photograph of this form. In Cogger 1975, a picture of a Cyrtodactylus louisiadensis from “Cape York” is provided. This individual bears no resemblance whatsoever to any louisiadensis I have ever seen but does match the description of the “Iron Range” form given in Wilson and Knowles 1988. The problem is that this specimen in Cogger’s photograph is indistinguishable from Cyrtodactylus intermedius of Thailand and India. This leaves me with three possible theories.
1. Cogger’s original picture was in arrears (and actually is a picture of C.intermedius from Thailand) and may be why it was not used in subsequent editions. Wilson and Knowles description was then based on Cogger’s picture and not on an actual specimen and has therefore reinforced the urban myth of the “Iron Range” form.
2. Wilson and Knowles description was based on a specimen or photograph other than Cogger’s picture and is a true variant of Cyrtodactylus louisiadensis.
3. The “Iron Range” form is a true entity in its own right and is possibly an extralimital population of C. intermedius or C.irianjayensis
Hopefully , I have tweaked some interest to reveal the true nature of this form.
The hatchlings are patterned similarly to adults but the patterning is brighter and more contrasting. In newly hatched juveniles, the bands at the front of the body are alternating brown and tan becoming black and white over the hind limbs and tail and usually finishing with a white tail tip. Small vertical white marks are found on the lips. The average SVL of a hatchling is 43mm and an average TL is 85mm.
Distribution and Habitat – Cyrtodactylus is a large genus extending from the western Pacific to Southern Europe. There is only one Australian species and an undescribed species from Christmas Island (an Australian territory) . Cyrtodactylus louisiadensis is found in North Eastern Queensland and as described before also occurs in New Guinea and the Solomon Islands. Within Australia there are two well recognised forms – a semi-arboreal form from isolated areas of thick coastal rainforest and a woodland, vine thicket and rock and cave inhabiting form extending from the coast to the harsher, drier inland sandstone country. This species forages on the ground, amongst foliage and vines, on tree trunks and logs and amongst rock fissures and boulders (non –vertical). It may also be found in association with farms and settled areas adjacent ideal habitat. This is a predominantly nocturnal species. The majority of individuals in captivity in this country originate from the non-rainforest form.
Sexing – Adult males are easily distinguished due to the prescence of significant hemipenal bulges and large hemipenal spur clusters (comprising 3-4 enlarged scales (may be asymmetrical) up to twice the size of adjacent scales). They also possess a row of at least 20 pores consisting of a variable number of both preanal pores and femoral pores separated by a series of enlarged but imperforate scales. Adult females have some enlargement in the hemipenal area but it is always less developed and rarely has a central depression. Hemipenal spur clusters are also smaller (spurs usually no more than 50% larger than adjacent scales). Preanal (and femoral) pores are usually absent but if present are not swollen and tan in colour as in males. Some adults show nocturnal colour dimorphism with males generally appearing paler (and more contrasting) in colour. I am not sure if this is a mood, dominance or random thing. It has been suggested by authors working with this species overseas that this dimorphism may also exist in juveniles and may be used as an aid in sexing them. I have not found this to be reliable in my specimens but long term studies have not been undertaken and this may be a feature of C.irianjayensis not C.louisiadensis..
Juveniles can be sexed reliably at 8-12 months of age with good feeding (once they have attained 60-80% of adult SVL). In some young males, preanal pore development may be visible at 50% of adult SVL.
Feeding – The Ring Tail gecko is an aggressive feeder, often launching itself 20 cm or more through the air to catch food items climbing up walls or attempting to flee. In the wild it feeds predominantly on large insects but it is also recorded as feeding on small frogs and other geckoes. In captivity, they will feed on any large insect (crickets, locusts, cockroaches, moths) and may also accept pink mice. It had intrigued me as too what calcium supply was relied on in the wild until I looked at a possible answer in some literature on Uroplatus geckoes. In the wild, these species consume small arboreal snails which would supply a significant calcium source. I have offered small (approximately 20% of the head size of the gecko) aquatic snails (from my fish tanks) and they are greedily consumed. Interestingly they are not chewed like a normal food item but are swallowed whole. I recommend that all other food items should be dusted with a suitable calcium supplement for at least two out of three feeds. In addition I supply a bowl of dry Calcium Carbonate powder or a granulated product like Bio-Cal (Australian Pigeon Company). Adults should be fed every 3-7 days during the warmer months and every 7-14 days during the colder moths although some adults will stop feeding during these cooler periods. Juveniles should be fed every 2-4 days throughout the year. Food item size for adults can be up to 80% of head size and up to 60% of head size in juveniles.
Housing
This species is equally at home in a terrestrial or arboreal environment and therefore its enclosure should be designed to cater for both behaviours. Cyrtodactylus lack adhesive lamellae on their toes and therefore have some difficulties with smooth surfaces such as glass. They do however have sharp claws that enable them to readily climb any other surfaces (this includes silicon remnants in the corners of fish tanks). Juveniles (due to their smaller size) can gain enough of a foothold to climb the walls of plastic containers. This species is not particularly aggressive and can be housed in groups or with other similar sized species. They are an active species and you should allow at least 30cm3 per individual. Within this space, they will often congregate in communal hide sites but usually forage individually. I have maintained this species as pairs or in groups of up to 6 individuals (1 male and 5 females). Only 1 male should be housed per enclosure. They do not fight viciously but do intimidate each other to the detriment of both individuals. I have successfully kept this species with Leaf tail gecko species (Saltuarius sp. and Platurus sp.).
Considering their natural habitat and distribution , they should be expected to be tolerant of high temperatures but in captivity this is not the case. I have found this species to be a little more tolerant than Leaf tail geckoes but it certainly has a sensitivity to temperature extremes. During winter periods , the temperature should be maintained between 20-25 o C. Additional heat can be supplied via a small wattage globe, heat tape or adequate increases above ambient temperature may be achieved from the provision of a UVB fluorescent light. At excessively low temperatures, this species becomes sluggish and will not feed. During summer, an ambient temperature of 27-30o C is recommended. I have encountered fatalities in this species when daytime temperatures have exceeded 34oC. In high temperatures, good ventilation is essential and individuals are at most risk in large plastic containers or in enclosures with fully enclosed glass or Perspex fronts. Using 8mm mesh for the front of all enclosures for this species can be helpful. It must be assumed that this tropical species avoids temperature extremes in its natural habitat by retreating to deep cavities in rocks and logs or seeking shelter in the depths of the rainforest.
Information provided in overseas texts often insists that in order to achieve any results with this species that it must be housed in high humidity environments. I have found that this is not the case with captive animals in my collection. In fact, most individuals in my collection actively seek out dry hide sites and spend little time in moist hides when they were provided. I have not experienced issues with dehydration or difficulties in shedding as recorded in overseas literature. I feel the primary reason for this is that the majority of Australian specimens originate from the inland populations in the drier part of this species range, an area dominated by large sandstone escarpments but it may simply be that C.irianjayensis has greater humidity needs than C. louisiadensis..
Appropriate UVB lighting is important for this species (minimum 5% UVB). Dietary calcium alone appears insufficient to provide prolific egg laying females with sufficient calcium for egg production. This is because this species produced hard shelled eggs. If only one or two clutches of eggs are laid, females cope well and show no evidence of ill health. Multiples clutches may result in a female showing signs consistent with hypocalcaemia (broken limbs, rubbery bones, seizures, egg binding). Provision of quality UVB lighting for at least 8-10 hours per day during the breeding season seems to prevent this. Whether or not UVB provision has a significant impact on juvenile development is uncertain as I have raised them successfully with and without UVB.
Suitable substrates for this species includes leaf litter, sand or a mixture of sand and coir peat. An area of deeper sand under a hide is useful for breeding purposes. Enclosure furniture should provide ground level hides (large upturned saucers, large bark pieces, sections of hollow logs) and climbing structures (vines, branches, rough textured walls).
Reproductive Behaviour
In the wild, breeding records for this species indicate that breeding is opportunistic. Most breedings are noted from September to March but personal communications with local herpetologists in North Queensland indicate that gravid females are not unusual in the period April to August.
In captivity, this species breeds mainly during the period October to April with less frequent clutches in the remainder of the year. I have observed apparent courtship or pre mating behaviour involving licking and biting over the shoulder and neck area but I have not observe mating which presumably takes place within the hides provided.
Juveniles of this species grow rapidly and can attain up to 70-80% of adult SVL in 12-18 months. At this size they are capable of reproduction.
Individuals may be maintained together throughout the year. I do not separate my stock because of the possibility of out-of-season clutches being laid. Heavily producing females may be rested however. Reintroduction to the male after separation rarely poses any problem beyond some initial over amorous intentions. Cooling can be utilised but I have not found it necessary as my animals are exposed to reduced natural ambient temperature within the room. I have not observed matings and therefore the period from mating to egg laying is difficult to determine. The first eggs laid by females that have been separated is generally 5-7 weeks after re-introduction. Gravid females increase moderately in abdominal bulk and the eggs may be seen easily through the abdominal wall skin.
Cytrtodactylus is somewhat unique amongst Australian geckoes (in addition to Heteronotia, Christinus, Nactus, Lepidodactylus, Hemidactylus and Gehyra sp.) in laying calcareous shelled eggs (not soft shelled). This feature places them in the subfamily Gekkonidae (the majority of Australian geckoes are in the subfamily Diplodactylinidae). Two eggs are laid per clutch (occasionally just 1 egg). The eggs are almost completely round and measure on average approximately 10-12 mm in diameter.
When freshly laid ,the eggs are for a short period partially soft and somewhat sticky and as a result it is not unusual for the eggs to be dented on the bottom from the substrate below and have pieces of substrate stuck to them. Do not try to remove stuck substrate as it will invariably pull out a plug of shell with it. Egg laying sites used by this species are variable. One would expect that this species should accept of semi moist containers as you would for every other species of gecko. This is not the norm and is likely to lead to disappointment as they invariably ignore them and lay in less appropriate sites if other sites are not available. The majority of eggs laid by my females are laid in a mound of dry sand under a hide site or in a container of dry sand and dry crumbled coir peat (50:50 mix). If alternative laying sites are not provided, some females will utilise a shallow scrape in a corner under litter or sand. This usually results in the eggs sticking to the enclosure floor or wall where any attempt to remove them results in egg damage. If a female does lay in a moist container, the eggs will often become mouldy quite rapidly.
Laying hard shelled eggs places an enormous burden on a females calcium metabolism. A single prolific female may lay up to 5-6 cluches per year with an average interclutch interval of 36-63 days being recorded (some may wait up to 150 + days between clutches). If the calcium utilisation required for this egg laying exceeds the individuals calcium supply or metabolic processing then two problems can arise. Initially you may notice thin shelled eggs. These eggs may be so thin that they collapse under the weight of the female when backfilling sand after laying. If calcium is not corrected when this warning sign appears then more serious problems may arise. If these females continued to lay they may develop systemic signs of calcium deficiency. These females will present with a combination of signs including seizures, paralysis (particularly hind legs), fractured jaws and may have multiple fractured limbs (due to weak bones collapsing under the lizards own body weight). If noticed early, some of these may be saved by giving oral calcium liquid directly to the mouth hourly for 3-6 hours and placing them under appropriate UVB lighting. If this has happened post egg laying then the prognosis is reasonable. If the eggs are yet to be laid then calcium supplementation needs to be provided at least twice daily until the eggs are laid. The prognosis is poor for these individuals and 70% may die. Of the survivors 70% will be re-effected at the next clutch .
The eggs should be incubated in a relatively dry medium (water:vermiculite 1:3 by weight or 1:30 by volume). Negligible swelling (compared to soft shelled eggs) occurs during the incubation period. No significant changes occur in the egg to give an indication of fertility except early signs of blood vessels when candled in the first week or two. Later candling is less discrete in its appearance. Eggs should ideally be incubated at a temperature of 27-30oC. At this temperature, average incubation times are 90-160 days. At room temperature, incubation can be successful but incubation periods up to 270 days have been recorded. At times, incubation periods follow no logic. In one season I placed three eggs (a clutch of 1 and a clutch of 2) laid only a few hours apart into a communal incubation container. The first egg hatched at 90 days, the second at 110 days and the third at over 190 days despite all existing under the same incubation environment. I follow one basic rule with this species, never throw an egg of this species out unless it has obviously no chance of sustaining life . I only discard eggs that are broken, severely discoloured, smelly or wet. If normal looking eggs are opened up at a time period considered to be far in excess of usual timing, it is not unusual to find a fully formed, live juvenile.
It appears that developed unhatched juveniles enter a “dormant” state and remain that way until triggered to emerge. The trigger is unknown but other Cyrtodactylus species (and some chameleons) can be triggered to hatch by sudden wetting of the well advanced eggs (after 100 days incubation) by placing wet sphagnum moss over the eggs. I am yet to try this with our species.
Unlike other gecko species, hatching is not preceded by egg sweating. The hatchling basically just kicks or pushes a plug of shell out of the side of the egg and emerges. I usually remove hatchlings from the incubation container after 6 hours and due to the fact that the eggs are hard shelled I feel that a hatchling left in the container may potentially crack the remaining egg if attempting to escape. Hatchlings will accept small crickets soon after hatching. I have experienced case of metabolic bone disease with this species and this is associated with either poor calcium supply (either pre hatching parental deficiency or nutritional deficiency once hatched) or poor calcium metabolism (due to lack of UVB lighting). Juveniles of this species will grow well if a well supplement diet is provided but seem to do better if they are provided with good quality UVB lighting as well.
Status in Captivity – This species is currently maintained in small but stable numbers. It popularity is increasing and as such its demand has increased in recent years. It is however prohibited or restricted by licencing schedules in some states. It is expected that this species should live for 7-10 years with a productive period of about 5 years on average.
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Dr Danny Brown
Private Breeder of Australian Lizards and Birds
Specialising in Geckoes/pygopods/skinks and Finches/softbills/waterfowl.
