Solomon Islands skink

Naming

The Solomon Islands skink was first described by John Edward Gray in 1856 as ''Corucia zebrata''. The generic name ''Corucia'' derives from the Latin 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, in reference to the animal's zebra-like stripes. Its common names 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'' of Australia, New Guinea, and Indonesia; all of which are found in the subfamily ''Lygosominae''.


The common Solomon Islands skink has a white sclera with its eyes while the northern Solomon Islands skink 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 and females averaging 22 inches in length when measured from nose to tip of tail. The common Solomon Islands skinks are slightly longer with the males averaging 28 inches and the females averaging 24 inches when measured from nose to tip of tail. The common Solomon Islands skink, at 850 grams , weighs more than the northern Solomon Islands skink, which weighs closer to 500 grams .

Distribution

The Solomon Islands skink is native to the Solomon Islands, a group of islands in the south-west Pacific Ocean. The common subspecies is found on the islands of Choiseul Island, New Georgia, Isabel, Guadalcanal, Ngela, Malaita, Makira , Ugi and Santa Ana. The northern subspecies is known from the islands of Bougainville and Buka and the Shortland Island Group. Bougainville and Buka are geographically part of the Solomons Archipelago, though politically part of Papua New Guinea. 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 , provided the epiphytic 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.

Behavior

The Solomon Islands skink is the world's largest species of extant skink; adults can reach a length of 32 inches 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....snipped... 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 cloacal 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 gripping 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. Like snakes, 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.

Habitat

The Solomon Islands skink is native to the Solomon Islands, a group of islands in the south-west Pacific Ocean. The common subspecies is found on the islands of Choiseul Island, New Georgia, Isabel, Guadalcanal, Ngela, Malaita, Makira , Ugi and Santa Ana. The northern subspecies is known from the islands of Bougainville and Buka and the Shortland Island Group. Bougainville and Buka are geographically part of the Solomons Archipelago, though politically part of Papua New Guinea. 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 , provided the epiphytic 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.

Reproduction

The Solomon Islands skink is one of the few species of reptile that lives in a communal group known as a circulus. The Solomon Islands skink reproduces by viviparous matrotrophy:c the female provides a placenta for its young, which are born after a gestation 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 in length and weigh 80 grams , whereas the common Solomon Islands skinks are 12 inches and 175 grams when they are born. This reduced size disparity led the former curator of reptiles at the Philadelphia Zoo, 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 twins will be born. At least one instance of triplets has occurred according to herpetologist Bert Langerwerf.

The newborn skink will stay within its circulus 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.

Food

Solomon Islands skinks are herbivores, feeding on the leaves, flowers, fruit, and growing shoots of several different species of plants. This includes the somewhat toxic ''Epipremnum pinnatum '' plant,a which the lizard eats without ill-effect.b Juvenile skinks often eat feces 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.

Predators

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.