Duvaucel's gecko (Hoplodactylus duvaucelii) is a species of lizard in the familyDiplodactylidae. The species is endemic to New Zealand and regarded as 'at risk' by the New Zealand Department of Conservation (DOC) due to distribution limitations.
The species was first named Platydactyle de Duvacel or Platydactylus duvaucelii in 1836 by André Marie Constant Duméril and Gabriel Bibron, who named the species after French naturalist Alfred Duvaucel, a French naturalist who explored India. The pair believed that the specimens were collected by Duvaucel when exploring Bengal as the museum specimens taken to Europe had been credited to him, and only later were the animals found to have come from New Zealand.[4][5]:79 In 1843 Leopold Fitzinger described the genus Hoplodactylus and named Duvaucel's gecko as the type species for this genus, leading to the currently used binomial name.[6]
Description
H. duvaucelii is the largest extant gecko species in New Zealand. The body measures 160mm snout-to-vent length (SVL) and approximately 30cm total, including the tail, weighing up to 120g.[7][8][9] Lifespan in the wild is estimated at 50 years, while in captivity this is lower at over 40 years.[10]
Duvaucel's gecko is a heavy-bodied lizard with a relatively large head and long toes with expanded pads. Its colouration is mainly grey, often with a faint olive-green hue. Usually, irregular blotches lie across the body from side to side between the back of the head and the base of the tail, which is never striped.[9] The front feet are smaller than those at the back. Foot area correlates with the SVL measurement, increasing as body size does at both the front and back feet.[11]
Reproduction
Duvaucel’s gecko is likely a polygynandrous species.[12] The mating period is between September and October. Viviparous juveniles are born after a 5-8 month gestation period during February and May.[9][13] Maturity is reached at seven years of age, and after this period juveniles will be birthed annually or biannually. One juvenile is produced during each reproductive cycle, though a maximum of two offspring has been known to occur.[14] This correlates with a low annual reproductive output compared to other New Zealand gecko species.[14] Little parental care input is made by the parents towards juveniles as they are mostly independent after birth,[13] however inside of the body viviparity provides better incubation conditions upon juveniles from the mother. Female individuals experience hormonal changes during the pre-ovulatory period, exhibiting increased oestradiol and progesterone compared with nonreproductive females.[10]
Courtship includes physical and chemosensory behaviour by both sexes. Males initiate courtship rituals by approaching the female and displaying tongue flicks. He will touch his snout to the female’s head, dorsal surface, and cloacal area and bite upon her body. The female individual will respond in defence with tail displays including flicks and thrashes, and biting the male. Upon this behaviour, the male will initiate the courtship grip, and if interested, the female will stiffen her body in the courtship pose and cease tail displays. Otherwise, the female will move away from the male and seek refuge. An rejected male will act aggressively towards the female and guard the entrance to her refuge site in an enlarged stance with arched back posture and extended legs. Mating begins when the male positions himself atop the female, join tails with the female, and inserts the hemipenis into the cloaca. Copulation then proceeds for approximately 14 minutes before hemipenis extraction and separation of individuals to seek refuge.[13]
Diet
Duvaucel's gecko is an opportunistic omnivore, relying on sugar resources in their diet from fruit, nectar, and honeydew, but also occasionally consuming invertebrates.[15][16] Omnivorous behaviour is due to the consumption of insects, arachnids, and smaller reptiles.[16] Honeydew is an annual resource, versus seasonal production of flowers and fruit and varied opportunities of predation events. As a nocturnal invertebrate, they forage both on the ground and arboreally in scrub, forest, and shoreline habitats in localised sites.[11]
Duvaucel's gecko prefers fruit from Kawakawa (Piper excelsum), Coprosma robusta, and Muehlenbeckia astonii species.[17] Individuals will consume only ripe fruiting bodies, foraging both in plants and below them.[18]Frugivory can contribute to the dispersal of the consumed plant species, though this is dependent on seed retention time in the gut. Adult individuals have a greater seed retention time than juveniles, excreting waste after multiple days and displaying the ability to disperse seeds away from the parent plant effectively.[17] There is a significantly lower retention time for non-native plants than native plants.[17] Observation of individuals repeatedly at the same location could suggest localised feeding over time until a resource is exhausted,[11] decreasing the effectiveness of dispersal behaviour when fruit resources are high.
Ngaio (Myoporum laetum) infested with high densities of honeydew-producing scale insects, namely endemic Coelostomidia zealandica, is a favoured resource over other insect-infested plant species.[19][20] Nectivorous feeding behaviour occurs by foraging along stems and foliage until a flower is located, then through an arching neck motion pushing the snout into the nectar repository of the flower. This contributes to the dispersal of pollen for ngaio as well as pohutukawa (Metrosideros excelsa) as it is captured on the throat whilst feeding.[18] Direct licking of honeydew droplets off plant stems is another method of obtaining this resource.[16] Adult Duvaucel's gecko are present in large amounts at heavily infested ngaio trees, whereas juveniles are more commonly located on trees with lower densities of honeydew.[20] Body size may therefore influence resource selection behaviour, displacing smaller individuals to lower-resource areas as a means of competition.[20]
Population partitioning of these two island groups has been observed, with individuals exhibiting a larger size on the Cook Strait Island subpopulations compared to the Northern Island subpopulations.[7]
Conservation work has aided in range expansion via the translocation of populations, including the 2016 reintroduction of 80 individuals to the mainland at predator free Tawharanui Open Sanctuary on the Tawharanui Peninsula.[25] Individuals have also been translocated to the Massey University captive breeding program in Auckland.[13]
Duvaucel's gecko are habitat generalists, occupying lowland forests, tussock vegetation, and coastal cliffs.[24][13][20][22][26]
Sympatry on offshore islands with predator species, particularly tuatara (Sphenodon punctatus) and kiore, has induced behavioural changes in the Duvaucel’s gecko. Overall, increased cryptic behaviour has been observed by Duvaucel’s gecko in the presence of these species.[24] Tuatara are also a nocturnal species with similar habitat and diet to Duvaucel’s gecko, leading to resource competition and exclusion during nighttime foraging.[7] Duvaucel’s gecko have adapted to this competitive stressor through temporal avoidance behaviour, foraging later into the night when tuatara are less active.[7] High site fidelity of Duvaucel’s gecko is a cause of increased aggression with territorial tuatara individuals in highly sympatric populations. This interaction and predation pressure by kiore has led to spatial avoidance at the microhabitat scale. For example, they are shifting microhabitats to more open spaces, occupying arboreal habitat higher up the forest strata, or becoming excluded from the forest altogether and occupying shoreline and coastal cliff regions. [7][16][22][24] By occupying different spatial and temporal ranges, Duvaucel’s gecko can reduce predation risk and competition enforced by predatory species.
In addition to habitat behaviour, predatory species presence has negative consequences for population metrics. Recruitment is restricted due to high predation on naïve juvenile individuals, causing long term conservation concerns for the Duvaucel’s gecko.[22][24] Increased cryptic behaviour causes difficulty in population monitoring as individuals are less active and occupy changing habitats. [24] Small populations are especially vulnerable, as they are limited in future recruitment possibilities and restricted to less genetic variation.[7][22]
Social behaviour
Duvaucel's gecko is basking under the light.
Duvaucel’s gecko are a highly social species. They show high site fidelity and maintain social groups by seeking refuge in social aggregations. Sun basking behaviour is performed throughout the day for temperature regulation. Chemosensory identification is used to communicate with conspecific individuals.
High site fidelity is reflected in the shared exploitation of local resources, including food and shelter sites.[7][20] This enables the building of sociality between individuals of a local population through familiarity.
Year round diurnal social aggregations are formed as refuge throughout the day. Groups of 2-8 individuals will aggregate together throughout the day in secluded areas, including rock crevices, tree hollows, or ground vegetation.[13][16] Aggregations will always have only one male present, with the other individuals compoased of females and their juvenile offspring.[13][26] Aggregation groups will often remain the same but are tolerant of incoming individuals provided there is space and they are not of the male sex. This enforces social familiarity between aggregate groups, as well as provides evidence for kin sociality because of tolerance of adults for juvenile individuals.[26] Aggregations are not compulsory for thermoregulation,[13][26] but may have mating benefits for males. Aggregation-forming males are larger than their solo counterparts, indicating female guarding or male competition benefits during the breeding season.[13][16][26]
Scent communication is carried out by marking sites and later identification by a conspecific individual. Snout rubbing or cloacal dragging across a resource marks the site with hormones, identified via tongue flicking behaviour that carries the scent into the highly developed olfactory system. This form of communication is used in male competition, mating opportunities, between juveniles and mothers, as well as the recognition of an unknown conspecific in the area.[13]
Conservation efforts
Past conservation of the Duvaucel's gecko has primarily focused on translocation and predator-free regimes to increase population growth. Translocations to the Massey University Reptile Facility captive breeding program have led to successful translocations since 2006, as well as study into the species.[13] An early study found that H. duvaucelii is well suited for captive breeding due to non-chronic elevation of stress related hormones in captive individuals.[13]
Individual and population sampling methods are focal points of conservation literature to better understand population metrics of this cryptic species. Artificial retreats formed of tree trunk coverings have been shown to increase population monitoring in the early post-translocation period, mimicking natural aggregation sites to encourage localised dispersal.[15][27]Radiotelemetry methods using backpack devices are effective in tracking movement and habitat use of Duvaucel's gecko individuals.[28] Additionally, footprint tracking enables population density and age estimates of the species, as well as wider habitat use.[11]
Parasitic associations have been found, including that of vector Geckobia naultina, which aggregate at the periphery of the eyes and cause a Rickettsia-like parasite in the blood.[21]
Future conservation concerns lie in climate change effects on islands, such as further range decrease. Predator control is critical to enabling the long term survival of this species.
Lizard is the common name used for all squamate reptiles other than snakes, encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The grouping is paraphyletic as some lizards are more closely related to snakes than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3-meter-long Komodo dragon.
The tuatara is a species of reptile endemic to New Zealand. Despite its close resemblance to lizards, it is part of a distinct lineage, the order Rhynchocephalia. The name tuatara is derived from the Māori language and means "peaks on the back".
The Lepidosauria is a subclass or superorder of reptiles, containing the orders Squamata and Rhynchocephalia. Squamata includes lizards and snakes. Squamata contains over 9,000 species, making it by far the most species-rich and diverse order of non-avian reptiles in the present day. Rhynchocephalia was a formerly widespread and diverse group of reptiles in the Mesozoic Era. However, it is represented by only one living species: the tuatara, a superficially lizard-like reptile native to New Zealand.
Hoplodactylus is a genus of geckos in the family Diplodactylidae. The genus is endemic to New Zealand, one of the seven genera of geckos found only in New Zealand. Hoplodactylus comprises two species of large to gigantic brownish lizards.
Naultinus is a genus of geckos that are endemic to New Zealand. On account of their striking colouration, species in the genus Naultinus are commonly known as green geckos. There are nine described species in the genus. Species in the genus share a number of traits that set them apart as quite different from the rest of the world's two thousand odd gecko species, which are generally brown in colour, ovivaparous, short-lived and nocturnal. In contrast, Naultinus are green, ovovivaparous, live up to 30 years or more and are strictly diurnal. New Zealand has a temperate, maritime climate, and in terms of distribution Naultinus is one of the southernmost gecko genera in the world — some species live in habitats in the South Island which receive regular snowfall in winter. Animals in this genus possess several physiological and behavioural adaptations to cope with these periods of low temperatures and adverse weather.
The Wellington green gecko is a species of gecko found only in the southern half of the North Island of New Zealand. It was previously considered a subspecies of the Auckland green gecko, and together called the common green gecko.
Isoplectron is a genus of cave wētā in the family Rhaphidophoridae with three species currently recognised. The genus is endemic to New Zealand and distributed throughout the country.
Oligosoma alani,, also known as the robust skink is the largest endemic skink to New Zealand. The robust skink is in the family Scincidae and found in the protected nature reserves of the Mercury Islands in the North Island of New Zealand. The robust skink has an at risk - recovering conservation status.
The black-eyed gecko, also known commonly as Whitaker's sticky-toed gecko, is a species of lizard in the family Diplodactylidae. An alpine gecko species, discovered in 1970, it inhabits high-altitude mountains in three areas of the South Island of New Zealand. It is the highest-altitude lizard species in New Zealand, living up to 2,200 m (7,200 ft) above sea level.
The harlequin gecko, formerly Hoplodactylus rakiurae, is a species of gecko, a lizard in the family Diplodactylidae. The species is endemic to Stewart Island / Rakiura in the far south of New Zealand, where it was discovered in 1969. In terms of distribution it is one of the southernmost gecko species in the world.
The Stephen's Island gecko, also known commonly as the Cook Strait striped gecko, Stephen's sticky-toed gecko, and the striped gecko, is a species of gecko in the genus Toropuku in the family Diplodactylidae. The species is endemic to New Zealand.
The forest gecko is a species of gecko that is endemic to New Zealand. Its Māori name is moko pirirākau. It is found in all parts of the country except the Far North and Canterbury. It is a protected species under the Wildlife Act 1953.
Woodworthia maculata, also known as the New Zealand common gecko or Raukawa gecko, is a species in the family Diplodactylidae. The species is endemic to New Zealand.
Dactylocnemis pacificus, the Pacific gecko or Pacific sticky-toed gecko, is a species in the family Gekkonidae, endemic to the North Island and offshore islands of New Zealand. D. pacificus is the only described species in the genus Dactylocnemis, but five offshore island forms may represent new species, one of which is the Mokohinau gecko.
The Canterbury gecko is a gecko found in the South Island of New Zealand. It is also known by the Māori names Waitaha gecko and Moko-pāpā, and as the brown gecko. It had previously been placed in a different genus and called Hoplodactylus brunneus, but further study split the genus Hoplodactylus into six genera, with some groups close to the former Hoplodactylus maculatus "Canterbury" being assigned to the new genus Woodworthia.
Archaeocroton sphenodonti, or the tuatara tick, is a species of tick that parasitises only the tuatara of New Zealand. It is found on just four of the twelve island groups where tuatara survive, preferring islands where the reptiles live in high densities. Larvae, nymphs, and adults all feed exclusively on tuatara blood, and ticks can survive for up to a year without a host. When tuatara are translocated, the tick has been lost or survives only in low densities in the new population. It is the only living species in the genus Archaeocroton.
The New Zealand Department of Conservation has introduced a number of animal and plant species to Mana Island, near Porirua, New Zealand, as part of an ecological restoration programme since taking over conservation management of the island in 1987. Some were reintroductions of species wiped out during years of agricultural use or the subsequent explosion in the number of house mice on the island. A pest control programme eliminated the mice by 1990 and many species have been introduced since. Notable successes include the spotted skink, Duvaucel's gecko and the flax weevil, which are now regarded as well established, and the yellow-crowned parakeet, which has been described as abundant and widespread. Attempts have been made to introduce several seabird species in what the Department of Conservation describes as "the world's most complex seabird translocation project"; results have been mixed.
Sanctuary Mountain Maungatautari, is a protected natural area in Waikato Region, New Zealand where the biodiversity of 3,400 ha of forest is being restored. The sanctuary covers the mountain peak, Maungatautari.
The Mokohinau gecko is an undescribed species of gecko found in the Mokohinau Islands, 100 km (62 mi) north of Auckland in the Auckland Region of New Zealand.
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↑ Thompson MB, Daugherty CH, Cree A, French DC, Gillingham JC, Barwick RE (1992). "Status and longevity of the tuatara, Sphenodon guntheri, and Duvaucel's gecko, Hoplodactylus duvaucelii, on North Brother Island, New Zealand". Journal of the Royal Society of New Zealand. 22 (2): 123–
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1 2 3 Alena, H.; Wotton, D. M.; Perry, G. L. W. (2023). "Seed retention times in New Zealand's largest gecko, Hoplodactylus duvaucelii, and implications for seed dispersal". New Zealand Journal of Ecology. 47 (1): 1–6. JSTOR48740222.
↑ Gardner-Gee, R.; Beggs, J. R. (2010). "Challenges in Food-Web Restoration: An Assessment of the Restoration Requirements of a Honeydew-Gecko Trophic Interaction in the Auckland Region, New Zealand". Restoration Ecology. 18 (s2): 295–303. Bibcode:2010ResEc..18S.295G. doi:10.1111/j.1526-100X.2010.00650.x.
1 2 3 4 5 6 Evans, A. E.; Towns, D. R.; Beggs, J. R. (2015). "Relative importance of sugar resources to endemic gecko populations in an isolated island ecosystem". New Zealand Journal of Ecology. 39 (2): 262–272. JSTOR26198719.
1 2 3 Barry, M., Perice, M. A., Heath, A. C. G., et al. (2011). A new blood parasite within the relict endemic New Zealand gecko Hoplodactylus duvaucelii. Veterinary Parasitology, 179(1-3). https://doi.org/10.1016/j.vetpar.2011.02.004
1 2 3 4 5 Hoare, J. M. (2006). Novel Predators and Naïve Prey: How Introduced Mammals Shape Behaviours and Populations of New Zealand Lizards. [Doctoral thesis, Victoria University of Wellington]. Open Access Te Herenga Waka-Victoria University of Wellington. https://doi.org/10.26686/wgtn.16922677.v1
↑ Trewick, Steve; Morgan-Richards, Mary (2014). NZ wild life: introducing the weird and wonderful character of natural New Zealand. Auckland, New Zealand. ISBN 9780143568896. OCLC 881301862.
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↑ Morgan-Richards, Mary; Hinlo, A. Rheyda; Smuts-Kennedy, Chris; Innes, John; Ji, Weihong; Barry, Manuela; Brunton, Dianne; Hitchmough, Rodney A. (2016). "Identification of a rare gecko from North Island New Zealand, and genetic assessment of its probable origin: a novel mainland conservation priority?". Journal of Herpetology. 50 (1): 77–86. doi:10.1670/13-128. ISSN 0022-1511. S2CID 83931126
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