Solomon Islands skink
Encyclopedia
The Solomon Islands skink (Corucia zebrata) is an arboreal species of skink
Skink
Skinks are lizards belonging to the family Scincidae. Together with several other lizard families, including Lacertidae , they comprise the superfamily or infraorder Scincomorpha...

 endemic to the Solomon Islands
Solomon Islands
Solomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...

. It is the largest known extant species of skink. Other common names for this species include the prehensile-tailed skink, monkey-tailed skink, giant skink, zebra skink, and monkey skink.

The Solomon Islands skink is completely herbivorous, eating many different fruits and vegetables including the pothos
Pothos (genus)
Pothos is a genus of flowering plants in the Araceae family. The common houseplant Epipremnum aureum, also known as the "Pothos," was once classified under the genus Pothos.-Selected species:*Pothos armatus C.E.C.Fisch....

 plant. It is one of the few species of reptile known to function within a social group or circulus
Circulus (zoology)
A circulus is a rarely occurring reptilian social group where there is interaction and personal exchange between individuals. Members will often protect and defend young - even if not of direct genetic linkage. "Circulus" is a Latin based term; one definition of the word is "a social gathering or...

. Both male and female specimens are known to be territorial and often hostile towards members not a part of their family group.

Corucia is a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

 genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

, containing a single species. However in 1997 it was determined that there are two subspecies of the Solomon Islands skink: the common monkey-tailed skink (Corucia zebrata zebrata) and the northern monkey-tailed skink (Corucia zebrata alfredschmidti). Among other variances, the northern skink is smaller and has darker eyes with a black sclera
Sclera
The sclera , also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest...

.

Extensive logging is a serious threat to the survival of this species. Consumption for food by indigenous Solomon Islanders and excessive pet trade exports has affected wild populations. Export of this species from the Solomon Islands is now restricted and the animal is protected under CITES appendix II.

Taxonomy and etymology

The Solomon Islands skink was first described by John Edward Gray
John Edward Gray
John Edward Gray, FRS was a British zoologist. He was the elder brother of George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray ....

 in 1856 as Corucia zebrata. The generic
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...

 name Corucia derives from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 word coruscus meaning "shimmering". This is in reference to Gray's description of "a play of colors effect from the body scales". Its specific name zebrata is a Latinized form of the word zebra
Zebra
Zebras are several species of African equids united by their distinctive black and white stripes. Their stripes come in different patterns unique to each individual. They are generally social animals that live in small harems to large herds...

, in reference to the animal's zebra-like stripes. Its common names (prehensile-tailed skink, monkey-tailed skink or monkey skink) refer to its fully prehensile tail which the species uses as a fifth limb for climbing.

Although appearances of skinks vary from island to island, a subspecies from the western islands of the Solomons Archipelago was described by Dr. Gunther Köhler in 1996 as C. z. alfredschmidti, its trinomial name was in honor of Alfred Schmidt.

The closest living relatives of C. zebrata are the Blue-tongued skinks of the genus Tiliqua and skinks of the genus Egernia
Egernia
Egernia is a genus of skinks that occurs in Australia. These skinks are ecologically diverse omnivores that inhabit a wide range of habitats...

of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...

, and Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

; all of which are found in the subfamily Lygosominae
Lygosominae
Lygosominae is the largest subfamily of skinks in the family Scincidae. The subfamily can be divided into a number of genus-groups. If the rarely used taxonomic rank of infrafamily is employed, the genus-groups would be designated as such, but such a move would require a formal description...

.

Distribution and habitat

The Solomon Islands skink is native to the Solomon Islands, a group of islands in the south-west Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

. The common subspecies (C. z. zebrata) is found on the islands of Choiseul Island
Choiseul Island
Choiseul Island, native name Lauru, is the largest island of the Choiseul Province, Solomon Islands, at .-Description:This island is named after Étienne François, duc de Choiseul....

, New Georgia
New Georgia
New Georgia is the largest island of the Western Province of the Solomon Islands.-Geography:This island is located in the New Georgia Group, an archipelago including most of the other larger islands in the province...

, Isabel
Isabel Province
Isabel Province is one of the provinces of the Solomon Islands. It has a population of around 30,000 . The capital is Buala on Santa Isabel Island.Santa Isabel is the longest Island in the Solomon Islands, South Pacific...

, Guadalcanal
Guadalcanal
Guadalcanal is a tropical island in the South-Western Pacific. The largest island in the Solomons, it was discovered by the Spanish expedition of Alvaro de Mendaña in 1568...

, Ngela, Malaita
Malaita
Malaita is the largest island of the Malaita Province in the Solomon Islands. A tropical and mountainous island, Malaita's pristine river systems and tropical forests have not been exploited. Malaita is the most populous island of the Solomon Islands, with 140,000 people or more than a third of the...

, Makira (Solomon Islands), Ugi
Ugi Island
Ugi Island is an island in the Solomon Islands; it is located in Makira-Ulawa Province....

 and Santa Ana. The northern subspecies (C. z. alfredschmidti) is known from the islands of Bougainville
Bougainville Island
Bougainville Island is the main island of the Autonomous Region of Bougainville of Papua New Guinea. This region is also known as Bougainville Province or the North Solomons. The population of the province is 175,160 , which includes the adjacent island of Buka and assorted outlying islands...

 and Buka
Buka Island
Buka Island is the second largest island in the Papua New Guinean province of Bougainville.- History :Buka was first occupied by humans in paleolithic times, some 30,000 years ago...

 and the Shortland Island Group. Bougainville and Buka are geographically part of the Solomons Archipelago, though politically part of Papua New Guinea
Papua New Guinea
Papua New Guinea , officially the Independent State of Papua New Guinea, is a country in Oceania, occupying the eastern half of the island of New Guinea and numerous offshore islands...

. Both subspecies of the Solomon Islands skink are strictly arboreal, usually inhabiting the upper canopy of forested areas throughout its range. It commonly occurs in the strangler fig tree
Ficus
Ficus is a genus of about 850 species of woody trees, shrubs, vines, epiphytes, and hemiepiphyte in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extending into the semi-warm temperate zone. The Common Fig Ficus is a genus of...

 (Ficus sp.), provided the epiphytic
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...

 growth of its several food plants are present. It occurs in trees in semi-cleared areas and cultivated food gardens, again provided its food plants occur there.

Biology

The Solomon Islands skink is the world's largest species of extant skink; adults can reach a length of 32 inches (81.3 cm) from nose to the tip of their tail when fully grown, with the tail accounting for more than half this length.

The Solomon Islands skink has a long, slender body, strong, short legs, and a triangular shaped head with small round eyes. The skink has a strong crushing jaw but the teeth are small and used for eating plant material. Its prehensile tail helps it maneuver from branch to branch with ease and gives the skink its more common names: monkey-tailed skink, prehensile-tailed skink, or monkey skink. Male Solomon Islands skinks tend to have a broader head and a more slender body shape than do female skinks. Males have a "V"-shaped pattern of scales just aft of the cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...

l opening, which is not present in female skinks.

The scales of Solomon Islands skinks are a dark green but are often speckled with light brown or black. The scales on the underside vary from light yellow to different shades of green. The toes on all four legs have thick, curved nails used for climbing and griping tree limbs.

As a nocturnal animal it relies heavily on its sense of smell, and uses it to identify its territory and other members of its group, called a circulus
Circulus (zoology)
A circulus is a rarely occurring reptilian social group where there is interaction and personal exchange between individuals. Members will often protect and defend young - even if not of direct genetic linkage. "Circulus" is a Latin based term; one definition of the word is "a social gathering or...

. Like snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...

s, the skink "smells" by flicking its tongue to gather scents and when the tongue is retracted it touches it to the opening of a Jacobson's organ at the roof of its mouth.

Subspecies

The common Solomon Islands skink (C. z. zebrata) has a white sclera
Sclera
The sclera , also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest...

 with its eyes while the northern Solomon Islands skink (C. z. alfredschmidti) has a black sclera. The iris of the northern Solomon Islands skink is a mix of green and yellow whereas the iris of the common Solomon Islands skink can vary from several different shades of green to orange to a dark black. According to Dr. Gunther Köhler, who described the northern subspecies, this subspecies possesses "larger dorsal and ventral scales" and has "seven instead of usually five parietal scales".

The northern Solomon Islands skink is the shorter of the two subspecies with males averaging 24 inches (61 cm) and females averaging 22 inches (55.9 cm) in length when measured from nose to tip of tail. The common Solomon Islands skinks are slightly longer with the males averaging 28 inches (71.1 cm) and the females averaging 24 inches (61 cm) when measured from nose to tip of tail. The common Solomon Islands skink, at 850 grams (1.9 lb), weighs more than the northern Solomon Islands skink, which weighs closer to 500 grams (1.1 lb).

Diet

Solomon Islands skinks are herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...

s, feeding on the leaves, flowers, fruit, and growing shoots of several different species of plants. This includes the somewhat toxic (due to high concentrations of calcium oxalate
Calcium oxalate
Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...

) Epipremnum pinnatum (cf.E. aureum)
Epipremnum aureum
Epipremnum aureum, also known as the Pothos , Money Plant, Silver Vine, Centipede tongavine, Devil's Ivy and Solomon Islands' Ivy, is an aroid native to southeastern Asia and New Guinea...

plant,a which the lizard eats without ill-effect.b Juvenile skinks often eat feces
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...

 from adults in order to acquire the essential microflora to digest their food. Newborn skinks have been observed consuming their placental sac after birth and will not feed on other food for the first 2 days.

Reproduction

The Solomon Islands skink is one of the few species of reptile that lives in a communal group known as a circulus
Circulus (zoology)
A circulus is a rarely occurring reptilian social group where there is interaction and personal exchange between individuals. Members will often protect and defend young - even if not of direct genetic linkage. "Circulus" is a Latin based term; one definition of the word is "a social gathering or...

. The Solomon Islands skink reproduces by viviparous matrotrophy:c the female provides a placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...

 for its young, which are born after a gestation
Gestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....

 period of six to eight months; this is a rare trait among reptiles. The newborn skink is of a large size compared to its mother; the northern Solomon Islands skinks are approximately 29 centimetres (11.4 in) in length and weigh 80 gram (0.176369809747902 lb), whereas the common Solomon Islands skinks are 12 inches (30.5 cm) and 175 gram (0.385808958823536 lb) when they are born. This reduced size disparity led the former curator of reptiles at the Philadelphia Zoo
Philadelphia Zoo
The Philadelphia Zoo, located in Philadelphia, Pennsylvania, on the west bank of the Schuylkill River, was the first zoo in the United States. Chartered by the Commonwealth of Pennsylvania on March 21, 1859, its opening was delayed by the American Civil War until July 1, 1874...

, Dr. Kevin Wright, to compare it to "a human mother giving birth to a six year–old". Almost all births are single babies but occasionally twin
Twin
A twin is one of two offspring produced in the same pregnancy. Twins can either be monozygotic , meaning that they develop from one zygote that splits and forms two embryos, or dizygotic because they develop from two separate eggs that are fertilized by two separate sperm.In contrast, a fetus...

s will be born. At least one instance of triplets
Multiple birth
A multiple birth occurs when more than one fetus is carried to term in a single pregnancy. Different names for multiple births are used, depending on the number of offspring. Common multiples are two and three, known as twins and triplets...

 has occurred according to herpetologist Bert Langerwerf.

The newborn skink will stay within its circulus
Circulus (zoology)
A circulus is a rarely occurring reptilian social group where there is interaction and personal exchange between individuals. Members will often protect and defend young - even if not of direct genetic linkage. "Circulus" is a Latin based term; one definition of the word is "a social gathering or...

 for six to twelve months during which time it will be protected by not only its parents but other unrelated adult skinks within the group. Around one year of age, sometimes earlier, the juvenile will move off to form a new family group. Individuals have been documented to stay within the group for several births without being expelled, however. Adult skinks have even been known to "adopt" orphaned young skinks into their groups. Females exhibit fierce protective behavior around the time of birth; this protectiveness of young is a rare occurrence in reptiles but is shorter in duration when compared to the protective behavior exhibited by a typical mammal.

Threats

Extensive logging is a serious ongoing threat to the survival of this species, as is consumption for food and export demand for the pet trade. Because of the large numbers of lizards that were being exported for the pet trade, the small region to which the skink is native, and its low reproductive rate, in 1992 Corucia zebrata was listed as a CITES Appendix II animal, which allows limits to be placed on the number of animals in commercial trade between countries.

Since there is no regulation on the rapid deforestation occurring in the Solomon Islands, limited export to recognized institutions may be needed to aid this species in genetic diversity for its survival via ex situ breeding programs. According to herpetologists who study the Solomon Islands skink, such as Dr. David Kirkpatrick and Dr. Kevin Wright, captive breeding alone is not practical as a sole method of species survival due to the limited number of offspring and long gestation periods.

In captivity

The Solomon Islands skink is represented in both public and private collections. The Philadelphia Zoo
Philadelphia Zoo
The Philadelphia Zoo, located in Philadelphia, Pennsylvania, on the west bank of the Schuylkill River, was the first zoo in the United States. Chartered by the Commonwealth of Pennsylvania on March 21, 1859, its opening was delayed by the American Civil War until July 1, 1874...

 has bred these skinks over multiple generations for the past 40 years. The keeping of the Solomon Islands skink in captivity is not without its challenges: as it is a large arboreal tropical animal, it requires a large arboreal enclosure. The dynamics of the skink's circulus means that not all groups do well when new animals are introduced. Despite successful breeding programs, their somewhat unique nature of single births and slow growth has made these programs challenging.

Biologist Michael Balsai of Temple University
Temple University
Temple University is a comprehensive public research university in Philadelphia, Pennsylvania, United States. Originally founded in 1884 by Dr. Russell Conwell, Temple University is among the nation's largest providers of professional education and prepares the largest body of professional...

 has noted a significant number of breedings between skinks from different islands has resulted in non-productive unions. Balsai's theory is that there are enough differences between animals from different islands that pairing of lizards from different locales will be unproductive, further frustrating many captive breeding attempts.

Footnotes

The Solomon Islands skink (Corucia zebrata) is an arboreal species of skink
Skink
Skinks are lizards belonging to the family Scincidae. Together with several other lizard families, including Lacertidae , they comprise the superfamily or infraorder Scincomorpha...

 endemic to the Solomon Islands
Solomon Islands
Solomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...

. It is the largest known extant species of skink. Other common names for this species include the prehensile-tailed skink, monkey-tailed skink, giant skink, zebra skink, and monkey skink.

The Solomon Islands skink is completely herbivorous, eating many different fruits and vegetables including the pothos
Pothos (genus)
Pothos is a genus of flowering plants in the Araceae family. The common houseplant Epipremnum aureum, also known as the "Pothos," was once classified under the genus Pothos.-Selected species:*Pothos armatus C.E.C.Fisch....

 plant. It is one of the few species of reptile known to function within a social group or circulus
Circulus (zoology)
A circulus is a rarely occurring reptilian social group where there is interaction and personal exchange between individuals. Members will often protect and defend young - even if not of direct genetic linkage. "Circulus" is a Latin based term; one definition of the word is "a social gathering or...

. Both male and female specimens are known to be territorial and often hostile towards members not a part of their family group.

Corucia is a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

 genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

, containing a single species. However in 1997 it was determined that there are two subspecies of the Solomon Islands skink: the common monkey-tailed skink (Corucia zebrata zebrata) and the northern monkey-tailed skink (Corucia zebrata alfredschmidti). Among other variances, the northern skink is smaller and has darker eyes with a black sclera
Sclera
The sclera , also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest...

.

Extensive logging is a serious threat to the survival of this species. Consumption for food by indigenous Solomon Islanders and excessive pet trade exports has affected wild populations. Export of this species from the Solomon Islands is now restricted and the animal is protected under CITES appendix II.

Taxonomy and etymology

The Solomon Islands skink was first described by John Edward Gray
John Edward Gray
John Edward Gray, FRS was a British zoologist. He was the elder brother of George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray ....

 in 1856 as Corucia zebrata. The generic
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...

 name Corucia derives from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 word coruscus meaning "shimmering". This is in reference to Gray's description of "a play of colors effect from the body scales". Its specific name zebrata is a Latinized form of the word zebra
Zebra
Zebras are several species of African equids united by their distinctive black and white stripes. Their stripes come in different patterns unique to each individual. They are generally social animals that live in small harems to large herds...

, in reference to the animal's zebra-like stripes. Its common names (prehensile-tailed skink, monkey-tailed skink or monkey skink) refer to its fully prehensile tail which the species uses as a fifth limb for climbing.

Although appearances of skinks vary from island to island, a subspecies from the western islands of the Solomons Archipelago was described by Dr. Gunther Köhler in 1996 as C. z. alfredschmidti, its trinomial name was in honor of Alfred Schmidt.

The closest living relatives of C. zebrata are the Blue-tongued skinks of the genus Tiliqua and skinks of the genus Egernia
Egernia
Egernia is a genus of skinks that occurs in Australia. These skinks are ecologically diverse omnivores that inhabit a wide range of habitats...

of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...

, and Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

; all of which are found in the subfamily Lygosominae
Lygosominae
Lygosominae is the largest subfamily of skinks in the family Scincidae. The subfamily can be divided into a number of genus-groups. If the rarely used taxonomic rank of infrafamily is employed, the genus-groups would be designated as such, but such a move would require a formal description...

.

Distribution and habitat

The Solomon Islands skink is native to the Solomon Islands, a group of islands in the south-west Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

. The common subspecies (C. z. zebrata) is found on the islands of Choiseul Island
Choiseul Island
Choiseul Island, native name Lauru, is the largest island of the Choiseul Province, Solomon Islands, at .-Description:This island is named after Étienne François, duc de Choiseul....

, New Georgia
New Georgia
New Georgia is the largest island of the Western Province of the Solomon Islands.-Geography:This island is located in the New Georgia Group, an archipelago including most of the other larger islands in the province...

, Isabel
Isabel Province
Isabel Province is one of the provinces of the Solomon Islands. It has a population of around 30,000 . The capital is Buala on Santa Isabel Island.Santa Isabel is the longest Island in the Solomon Islands, South Pacific...

, Guadalcanal
Guadalcanal
Guadalcanal is a tropical island in the South-Western Pacific. The largest island in the Solomons, it was discovered by the Spanish expedition of Alvaro de Mendaña in 1568...

, Ngela, Malaita
Malaita
Malaita is the largest island of the Malaita Province in the Solomon Islands. A tropical and mountainous island, Malaita's pristine river systems and tropical forests have not been exploited. Malaita is the most populous island of the Solomon Islands, with 140,000 people or more than a third of the...

, Makira (Solomon Islands), Ugi
Ugi Island
Ugi Island is an island in the Solomon Islands; it is located in Makira-Ulawa Province....

 and Santa Ana. The northern subspecies (C. z. alfredschmidti) is known from the islands of Bougainville
Bougainville Island
Bougainville Island is the main island of the Autonomous Region of Bougainville of Papua New Guinea. This region is also known as Bougainville Province or the North Solomons. The population of the province is 175,160 , which includes the adjacent island of Buka and assorted outlying islands...

 and Buka
Buka Island
Buka Island is the second largest island in the Papua New Guinean province of Bougainville.- History :Buka was first occupied by humans in paleolithic times, some 30,000 years ago...

 and the Shortland Island Group. Bougainville and Buka are geographically part of the Solomons Archipelago, though politically part of Papua New Guinea
Papua New Guinea
Papua New Guinea , officially the Independent State of Papua New Guinea, is a country in Oceania, occupying the eastern half of the island of New Guinea and numerous offshore islands...

. Both subspecies of the Solomon Islands skink are strictly arboreal, usually inhabiting the upper canopy of forested areas throughout its range. It commonly occurs in the strangler fig tree
Ficus
Ficus is a genus of about 850 species of woody trees, shrubs, vines, epiphytes, and hemiepiphyte in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extending into the semi-warm temperate zone. The Common Fig Ficus is a genus of...

 (Ficus sp.), provided the epiphytic
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...

 growth of its several food plants are present. It occurs in trees in semi-cleared areas and cultivated food gardens, again provided its food plants occur there.

Biology

The Solomon Islands skink is the world's largest species of extant skink; adults can reach a length of 32 inches (81.3 cm) from nose to the tip of their tail when fully grown, with the tail accounting for more than half this length.

The Solomon Islands skink has a long, slender body, strong, short legs, and a triangular shaped head with small round eyes. The skink has a strong crushing jaw but the teeth are small and used for eating plant material. Its prehensile tail helps it maneuver from branch to branch with ease and gives the skink its more common names: monkey-tailed skink, prehensile-tailed skink, or monkey skink. Male Solomon Islands skinks tend to have a broader head and a more slender body shape than do female skinks. Males have a "V"-shaped pattern of scales just aft of the cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...

l opening, which is not present in female skinks.

The scales of Solomon Islands skinks are a dark green but are often speckled with light brown or black. The scales on the underside vary from light yellow to different shades of green. The toes on all four legs have thick, curved nails used for climbing and griping tree limbs.

As a nocturnal animal it relies heavily on its sense of smell, and uses it to identify its territory and other members of its group, called a circulus
Circulus (zoology)
A circulus is a rarely occurring reptilian social group where there is interaction and personal exchange between individuals. Members will often protect and defend young - even if not of direct genetic linkage. "Circulus" is a Latin based term; one definition of the word is "a social gathering or...

. Like snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...

s, the skink "smells" by flicking its tongue to gather scents and when the tongue is retracted it touches it to the opening of a Jacobson's organ at the roof of its mouth.

Subspecies

The common Solomon Islands skink (C. z. zebrata) has a white sclera
Sclera
The sclera , also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest...

 with its eyes while the northern Solomon Islands skink (C. z. alfredschmidti) has a black sclera. The iris of the northern Solomon Islands skink is a mix of green and yellow whereas the iris of the common Solomon Islands skink can vary from several different shades of green to orange to a dark black. According to Dr. Gunther Köhler, who described the northern subspecies, this subspecies possesses "larger dorsal and ventral scales" and has "seven instead of usually five parietal scales".

The northern Solomon Islands skink is the shorter of the two subspecies with males averaging 24 inches (61 cm) and females averaging 22 inches (55.9 cm) in length when measured from nose to tip of tail. The common Solomon Islands skinks are slightly longer with the males averaging 28 inches (71.1 cm) and the females averaging 24 inches (61 cm) when measured from nose to tip of tail. The common Solomon Islands skink, at 850 grams (1.9 lb), weighs more than the northern Solomon Islands skink, which weighs closer to 500 grams (1.1 lb).

Diet

Solomon Islands skinks are herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...

s, feeding on the leaves, flowers, fruit, and growing shoots of several different species of plants. This includes the somewhat toxic (due to high concentrations of calcium oxalate
Calcium oxalate
Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...

) Epipremnum pinnatum (cf.E. aureum)
Epipremnum aureum
Epipremnum aureum, also known as the Pothos , Money Plant, Silver Vine, Centipede tongavine, Devil's Ivy and Solomon Islands' Ivy, is an aroid native to southeastern Asia and New Guinea...

plant,a which the lizard eats without ill-effect.b Juvenile skinks often eat feces
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...

 from adults in order to acquire the essential microflora to digest their food. Newborn skinks have been observed consuming their placental sac after birth and will not feed on other food for the first 2 days.

Reproduction

The Solomon Islands skink is one of the few species of reptile that lives in a communal group known as a circulus
Circulus (zoology)
A circulus is a rarely occurring reptilian social group where there is interaction and personal exchange between individuals. Members will often protect and defend young - even if not of direct genetic linkage. "Circulus" is a Latin based term; one definition of the word is "a social gathering or...

. The Solomon Islands skink reproduces by viviparous matrotrophy:c the female provides a placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...

 for its young, which are born after a gestation
Gestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....

 period of six to eight months; this is a rare trait among reptiles. The newborn skink is of a large size compared to its mother; the northern Solomon Islands skinks are approximately 29 centimetres (11.4 in) in length and weigh 80 gram (0.176369809747902 lb), whereas the common Solomon Islands skinks are 12 inches (30.5 cm) and 175 gram (0.385808958823536 lb) when they are born. This reduced size disparity led the former curator of reptiles at the Philadelphia Zoo
Philadelphia Zoo
The Philadelphia Zoo, located in Philadelphia, Pennsylvania, on the west bank of the Schuylkill River, was the first zoo in the United States. Chartered by the Commonwealth of Pennsylvania on March 21, 1859, its opening was delayed by the American Civil War until July 1, 1874...

, Dr. Kevin Wright, to compare it to "a human mother giving birth to a six year–old". Almost all births are single babies but occasionally twin
Twin
A twin is one of two offspring produced in the same pregnancy. Twins can either be monozygotic , meaning that they develop from one zygote that splits and forms two embryos, or dizygotic because they develop from two separate eggs that are fertilized by two separate sperm.In contrast, a fetus...

s will be born. At least one instance of triplets
Multiple birth
A multiple birth occurs when more than one fetus is carried to term in a single pregnancy. Different names for multiple births are used, depending on the number of offspring. Common multiples are two and three, known as twins and triplets...

 has occurred according to herpetologist Bert Langerwerf.

The newborn skink will stay within its circulus
Circulus (zoology)
A circulus is a rarely occurring reptilian social group where there is interaction and personal exchange between individuals. Members will often protect and defend young - even if not of direct genetic linkage. "Circulus" is a Latin based term; one definition of the word is "a social gathering or...

 for six to twelve months during which time it will be protected by not only its parents but other unrelated adult skinks within the group. Around one year of age, sometimes earlier, the juvenile will move off to form a new family group. Individuals have been documented to stay within the group for several births without being expelled, however. Adult skinks have even been known to "adopt" orphaned young skinks into their groups. Females exhibit fierce protective behavior around the time of birth; this protectiveness of young is a rare occurrence in reptiles but is shorter in duration when compared to the protective behavior exhibited by a typical mammal.

Threats

Extensive logging is a serious ongoing threat to the survival of this species, as is consumption for food and export demand for the pet trade. Because of the large numbers of lizards that were being exported for the pet trade, the small region to which the skink is native, and its low reproductive rate, in 1992 Corucia zebrata was listed as a CITES Appendix II animal, which allows limits to be placed on the number of animals in commercial trade between countries.

Since there is no regulation on the rapid deforestation occurring in the Solomon Islands, limited export to recognized institutions may be needed to aid this species in genetic diversity for its survival via ex situ breeding programs. According to herpetologists who study the Solomon Islands skink, such as Dr. David Kirkpatrick and Dr. Kevin Wright, captive breeding alone is not practical as a sole method of species survival due to the limited number of offspring and long gestation periods.

In captivity

The Solomon Islands skink is represented in both public and private collections. The Philadelphia Zoo
Philadelphia Zoo
The Philadelphia Zoo, located in Philadelphia, Pennsylvania, on the west bank of the Schuylkill River, was the first zoo in the United States. Chartered by the Commonwealth of Pennsylvania on March 21, 1859, its opening was delayed by the American Civil War until July 1, 1874...

 has bred these skinks over multiple generations for the past 40 years. The keeping of the Solomon Islands skink in captivity is not without its challenges: as it is a large arboreal tropical animal, it requires a large arboreal enclosure. The dynamics of the skink's circulus means that not all groups do well when new animals are introduced. Despite successful breeding programs, their somewhat unique nature of single births and slow growth has made these programs challenging.

Biologist Michael Balsai of Temple University
Temple University
Temple University is a comprehensive public research university in Philadelphia, Pennsylvania, United States. Originally founded in 1884 by Dr. Russell Conwell, Temple University is among the nation's largest providers of professional education and prepares the largest body of professional...

 has noted a significant number of breedings between skinks from different islands has resulted in non-productive unions. Balsai's theory is that there are enough differences between animals from different islands that pairing of lizards from different locales will be unproductive, further frustrating many captive breeding attempts.

Footnotes

The Solomon Islands skink (Corucia zebrata) is an arboreal species of skink
Skink
Skinks are lizards belonging to the family Scincidae. Together with several other lizard families, including Lacertidae , they comprise the superfamily or infraorder Scincomorpha...

 endemic to the Solomon Islands
Solomon Islands
Solomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...

. It is the largest known extant species of skink. Other common names for this species include the prehensile-tailed skink, monkey-tailed skink, giant skink, zebra skink, and monkey skink.

The Solomon Islands skink is completely herbivorous, eating many different fruits and vegetables including the pothos
Pothos (genus)
Pothos is a genus of flowering plants in the Araceae family. The common houseplant Epipremnum aureum, also known as the "Pothos," was once classified under the genus Pothos.-Selected species:*Pothos armatus C.E.C.Fisch....

 plant. It is one of the few species of reptile known to function within a social group or circulus
Circulus (zoology)
A circulus is a rarely occurring reptilian social group where there is interaction and personal exchange between individuals. Members will often protect and defend young - even if not of direct genetic linkage. "Circulus" is a Latin based term; one definition of the word is "a social gathering or...

. Both male and female specimens are known to be territorial and often hostile towards members not a part of their family group.

Corucia is a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

 genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

, containing a single species. However in 1997 it was determined that there are two subspecies of the Solomon Islands skink: the common monkey-tailed skink (Corucia zebrata zebrata) and the northern monkey-tailed skink (Corucia zebrata alfredschmidti). Among other variances, the northern skink is smaller and has darker eyes with a black sclera
Sclera
The sclera , also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest...

.

Extensive logging is a serious threat to the survival of this species. Consumption for food by indigenous Solomon Islanders and excessive pet trade exports has affected wild populations. Export of this species from the Solomon Islands is now restricted and the animal is protected under CITES appendix II.

Taxonomy and etymology

The Solomon Islands skink was first described by John Edward Gray
John Edward Gray
John Edward Gray, FRS was a British zoologist. He was the elder brother of George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray ....

 in 1856 as Corucia zebrata. The generic
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...

 name Corucia derives from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 word coruscus meaning "shimmering". This is in reference to Gray's description of "a play of colors effect from the body scales". Its specific name zebrata is a Latinized form of the word zebra
Zebra
Zebras are several species of African equids united by their distinctive black and white stripes. Their stripes come in different patterns unique to each individual. They are generally social animals that live in small harems to large herds...

, in reference to the animal's zebra-like stripes. Its common names (prehensile-tailed skink, monkey-tailed skink or monkey skink) refer to its fully prehensile tail which the species uses as a fifth limb for climbing.

Although appearances of skinks vary from island to island, a subspecies from the western islands of the Solomons Archipelago was described by Dr. Gunther Köhler in 1996 as C. z. alfredschmidti, its trinomial name was in honor of Alfred Schmidt.

The closest living relatives of C. zebrata are the Blue-tongued skinks of the genus Tiliqua and skinks of the genus Egernia
Egernia
Egernia is a genus of skinks that occurs in Australia. These skinks are ecologically diverse omnivores that inhabit a wide range of habitats...

of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...

, and Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

; all of which are found in the subfamily Lygosominae
Lygosominae
Lygosominae is the largest subfamily of skinks in the family Scincidae. The subfamily can be divided into a number of genus-groups. If the rarely used taxonomic rank of infrafamily is employed, the genus-groups would be designated as such, but such a move would require a formal description...

.

Distribution and habitat

The Solomon Islands skink is native to the Solomon Islands, a group of islands in the south-west Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

. The common subspecies (C. z. zebrata) is found on the islands of Choiseul Island
Choiseul Island
Choiseul Island, native name Lauru, is the largest island of the Choiseul Province, Solomon Islands, at .-Description:This island is named after Étienne François, duc de Choiseul....

, New Georgia
New Georgia
New Georgia is the largest island of the Western Province of the Solomon Islands.-Geography:This island is located in the New Georgia Group, an archipelago including most of the other larger islands in the province...

, Isabel
Isabel Province
Isabel Province is one of the provinces of the Solomon Islands. It has a population of around 30,000 . The capital is Buala on Santa Isabel Island.Santa Isabel is the longest Island in the Solomon Islands, South Pacific...

, Guadalcanal
Guadalcanal
Guadalcanal is a tropical island in the South-Western Pacific. The largest island in the Solomons, it was discovered by the Spanish expedition of Alvaro de Mendaña in 1568...

, Ngela, Malaita
Malaita
Malaita is the largest island of the Malaita Province in the Solomon Islands. A tropical and mountainous island, Malaita's pristine river systems and tropical forests have not been exploited. Malaita is the most populous island of the Solomon Islands, with 140,000 people or more than a third of the...

, Makira (Solomon Islands), Ugi
Ugi Island
Ugi Island is an island in the Solomon Islands; it is located in Makira-Ulawa Province....

 and Santa Ana. The northern subspecies (C. z. alfredschmidti) is known from the islands of Bougainville
Bougainville Island
Bougainville Island is the main island of the Autonomous Region of Bougainville of Papua New Guinea. This region is also known as Bougainville Province or the North Solomons. The population of the province is 175,160 , which includes the adjacent island of Buka and assorted outlying islands...

 and Buka
Buka Island
Buka Island is the second largest island in the Papua New Guinean province of Bougainville.- History :Buka was first occupied by humans in paleolithic times, some 30,000 years ago...

 and the Shortland Island Group. Bougainville and Buka are geographically part of the Solomons Archipelago, though politically part of Papua New Guinea
Papua New Guinea
Papua New Guinea , officially the Independent State of Papua New Guinea, is a country in Oceania, occupying the eastern half of the island of New Guinea and numerous offshore islands...

. Both subspecies of the Solomon Islands skink are strictly arboreal, usually inhabiting the upper canopy of forested areas throughout its range. It commonly occurs in the strangler fig tree
Ficus
Ficus is a genus of about 850 species of woody trees, shrubs, vines, epiphytes, and hemiepiphyte in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extending into the semi-warm temperate zone. The Common Fig Ficus is a genus of...

 (Ficus sp.), provided the epiphytic
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...

 growth of its several food plants are present. It occurs in trees in semi-cleared areas and cultivated food gardens, again provided its food plants occur there.

Biology

The Solomon Islands skink is the world's largest species of extant skink; adults can reach a length of 32 inches (81.3 cm) from nose to the tip of their tail when fully grown, with the tail accounting for more than half this length.

The Solomon Islands skink has a long, slender body, strong, short legs, and a triangular shaped head with small round eyes. The skink has a strong crushing jaw but the teeth are small and used for eating plant material. Its prehensile tail helps it maneuver from branch to branch with ease and gives the skink its more common names: monkey-tailed skink, prehensile-tailed skink, or monkey skink. Male Solomon Islands skinks tend to have a broader head and a more slender body shape than do female skinks. Males have a "V"-shaped pattern of scales just aft of the cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...

l opening, which is not present in female skinks.

The scales of Solomon Islands skinks are a dark green but are often speckled with light brown or black. The scales on the underside vary from light yellow to different shades of green. The toes on all four legs have thick, curved nails used for climbing and griping tree limbs.

As a nocturnal animal it relies heavily on its sense of smell, and uses it to identify its territory and other members of its group, called a circulus
Circulus (zoology)
A circulus is a rarely occurring reptilian social group where there is interaction and personal exchange between individuals. Members will often protect and defend young - even if not of direct genetic linkage. "Circulus" is a Latin based term; one definition of the word is "a social gathering or...

. Like snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...

s, the skink "smells" by flicking its tongue to gather scents and when the tongue is retracted it touches it to the opening of a Jacobson's organ at the roof of its mouth.

Subspecies

The common Solomon Islands skink (C. z. zebrata) has a white sclera
Sclera
The sclera , also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest...

 with its eyes while the northern Solomon Islands skink (C. z. alfredschmidti) has a black sclera. The iris of the northern Solomon Islands skink is a mix of green and yellow whereas the iris of the common Solomon Islands skink can vary from several different shades of green to orange to a dark black. According to Dr. Gunther Köhler, who described the northern subspecies, this subspecies possesses "larger dorsal and ventral scales" and has "seven instead of usually five parietal scales".

The northern Solomon Islands skink is the shorter of the two subspecies with males averaging 24 inches (61 cm) and females averaging 22 inches (55.9 cm) in length when measured from nose to tip of tail. The common Solomon Islands skinks are slightly longer with the males averaging 28 inches (71.1 cm) and the females averaging 24 inches (61 cm) when measured from nose to tip of tail. The common Solomon Islands skink, at 850 grams (1.9 lb), weighs more than the northern Solomon Islands skink, which weighs closer to 500 grams (1.1 lb).

Diet

Solomon Islands skinks are herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...

s, feeding on the leaves, flowers, fruit, and growing shoots of several different species of plants. This includes the somewhat toxic (due to high concentrations of calcium oxalate
Calcium oxalate
Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...

) Epipremnum pinnatum (cf.E. aureum)
Epipremnum aureum
Epipremnum aureum, also known as the Pothos , Money Plant, Silver Vine, Centipede tongavine, Devil's Ivy and Solomon Islands' Ivy, is an aroid native to southeastern Asia and New Guinea...

plant,a which the lizard eats without ill-effect.b Juvenile skinks often eat feces
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...

 from adults in order to acquire the essential microflora to digest their food. Newborn skinks have been observed consuming their placental sac after birth and will not feed on other food for the first 2 days.

Reproduction

The Solomon Islands skink is one of the few species of reptile that lives in a communal group known as a circulus
Circulus (zoology)
A circulus is a rarely occurring reptilian social group where there is interaction and personal exchange between individuals. Members will often protect and defend young - even if not of direct genetic linkage. "Circulus" is a Latin based term; one definition of the word is "a social gathering or...

. The Solomon Islands skink reproduces by viviparous matrotrophy:c the female provides a placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...

 for its young, which are born after a gestation
Gestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....

 period of six to eight months; this is a rare trait among reptiles. The newborn skink is of a large size compared to its mother; the northern Solomon Islands skinks are approximately 29 centimetres (11.4 in) in length and weigh 80 gram (0.176369809747902 lb), whereas the common Solomon Islands skinks are 12 inches (30.5 cm) and 175 gram (0.385808958823536 lb) when they are born. This reduced size disparity led the former curator of reptiles at the Philadelphia Zoo
Philadelphia Zoo
The Philadelphia Zoo, located in Philadelphia, Pennsylvania, on the west bank of the Schuylkill River, was the first zoo in the United States. Chartered by the Commonwealth of Pennsylvania on March 21, 1859, its opening was delayed by the American Civil War until July 1, 1874...

, Dr. Kevin Wright, to compare it to "a human mother giving birth to a six year–old". Almost all births are single babies but occasionally twin
Twin
A twin is one of two offspring produced in the same pregnancy. Twins can either be monozygotic , meaning that they develop from one zygote that splits and forms two embryos, or dizygotic because they develop from two separate eggs that are fertilized by two separate sperm.In contrast, a fetus...

s will be born. At least one instance of triplets
Multiple birth
A multiple birth occurs when more than one fetus is carried to term in a single pregnancy. Different names for multiple births are used, depending on the number of offspring. Common multiples are two and three, known as twins and triplets...

 has occurred according to herpetologist Bert Langerwerf.

The newborn skink will stay within its circulus
Circulus (zoology)
A circulus is a rarely occurring reptilian social group where there is interaction and personal exchange between individuals. Members will often protect and defend young - even if not of direct genetic linkage. "Circulus" is a Latin based term; one definition of the word is "a social gathering or...

 for six to twelve months during which time it will be protected by not only its parents but other unrelated adult skinks within the group. Around one year of age, sometimes earlier, the juvenile will move off to form a new family group. Individuals have been documented to stay within the group for several births without being expelled, however. Adult skinks have even been known to "adopt" orphaned young skinks into their groups. Females exhibit fierce protective behavior around the time of birth; this protectiveness of young is a rare occurrence in reptiles but is shorter in duration when compared to the protective behavior exhibited by a typical mammal.

Threats

Extensive logging is a serious ongoing threat to the survival of this species, as is consumption for food and export demand for the pet trade. Because of the large numbers of lizards that were being exported for the pet trade, the small region to which the skink is native, and its low reproductive rate, in 1992 Corucia zebrata was listed as a CITES Appendix II animal, which allows limits to be placed on the number of animals in commercial trade between countries.

Since there is no regulation on the rapid deforestation occurring in the Solomon Islands, limited export to recognized institutions may be needed to aid this species in genetic diversity for its survival via ex situ breeding programs. According to herpetologists who study the Solomon Islands skink, such as Dr. David Kirkpatrick and Dr. Kevin Wright, captive breeding alone is not practical as a sole method of species survival due to the limited number of offspring and long gestation periods.

In captivity

The Solomon Islands skink is represented in both public and private collections. The Philadelphia Zoo
Philadelphia Zoo
The Philadelphia Zoo, located in Philadelphia, Pennsylvania, on the west bank of the Schuylkill River, was the first zoo in the United States. Chartered by the Commonwealth of Pennsylvania on March 21, 1859, its opening was delayed by the American Civil War until July 1, 1874...

 has bred these skinks over multiple generations for the past 40 years. The keeping of the Solomon Islands skink in captivity is not without its challenges: as it is a large arboreal tropical animal, it requires a large arboreal enclosure. The dynamics of the skink's circulus means that not all groups do well when new animals are introduced. Despite successful breeding programs, their somewhat unique nature of single births and slow growth has made these programs challenging.

Biologist Michael Balsai of Temple University
Temple University
Temple University is a comprehensive public research university in Philadelphia, Pennsylvania, United States. Originally founded in 1884 by Dr. Russell Conwell, Temple University is among the nation's largest providers of professional education and prepares the largest body of professional...

 has noted a significant number of breedings between skinks from different islands has resulted in non-productive unions. Balsai's theory is that there are enough differences between animals from different islands that pairing of lizards from different locales will be unproductive, further frustrating many captive breeding attempts.

Footnotes

  • Note a:University of Nebraska (2006) "Plants which contain oxalate
    Oxalate
    Oxalate , is the dianion with formula C2O42− also written 22−. Either name is often used for derivatives, such as disodium oxalate, 2C2O42−, or an ester of oxalic acid Oxalate (IUPAC: ethanedioate), is the dianion with formula C2O42− also written (COO)22−. Either...

     salts produce mucous membrane
    Mucous membrane
    The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...

     irritation and pain and/or swelling of mouth, lips, tongue, esophagus and stomach."
  • Note b:Satter (2007) "note that it tends to turn their feces
    Feces
    Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...

     reddish in color"
  • Note c:"Matrotrophy is the nourishment of embryos by resources provided between fertilization and parturition."

External links

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