Whitaker’s skink (Oligosoma whitakeri)

Synonyms: Cyclodina whitakeri
KingdomAnimalia
PhylumChordata
ClassReptilia
OrderSquamata
FamilyScincidae
GenusOligosoma (1)
SizeLength: up to 20 cm (2)
Weightup to 20 g (2)

Classified as Vulnerable (VU) on the IUCN Red List (3).

A medium-sized and rather attractively marked lizard, Whitaker’s skink has a long body, short but well-developed limbs, and smooth scales (4) (5). The back is yellowish-tan in colour, with many small, irregularly scattered black and yellowish flecks, while the sides are dark chocolate brown, with yellowish blotches, from the ear to the hindlimbs. The underside of the body is yellowish-orange, with darker flecks along the sides, and the throat is grey and speckled (4) (6). The limbs are marked with irregular yellow and brown blotches on the outer surface, and have a pinkish orange inner surface, with a few darker blotches. A white ‘tear drop’, edged in black, extends below the eye (4). Previously classified within the genus Cyclodina, recent molecular evidence suggests that Whitaker’s skink, together with all native New Zealand skinks, should be placed within a single genus, Oligosoma (1).

Whitaker’s skink is endemic to New Zealand, where the few remaining populations are restricted to Middle Island in the Mercury Islands, Castle Island, and on the mainland of New Zealand’s North Island, at Pukerua Bay, north of Wellington (4) (7). Further populations have also been established on Korapuki, Stanley and Red Mercury Islands (2) (7).

Vulnerable to water loss through the skin, Whitaker’s skink prefers warm, moist environments, and is commonly found in and around seabird burrows, in leaf litter and amongst boulders (2) (7) (8).

Whitaker’s skink is most active soon after dark, foraging within seabird burrows and inside boulder banks for a range of invertebrate prey, including spiders (7) (8). The species’ association with seabird burrows may also suggest that it feeds to some extent on material spilt by birds when feeding their chicks (8). Like most New Zealand lizards, Whitaker’s skink gives birth to live young, usually producing a litter of between two and four offspring in the autumn, after a gestation period of a few months, and is thought to breed either once a year or once every other year (2) (8) (9). Whitaker’s skinks do not become mature until around three to four years old (8), but may live for up to 20 years (7).

As with many other New Zealand lizards, the population and distribution of Whitaker’s skink has been greatly reduced as a result of predation by introduced mammals such as mice, cats and weasels (7) (8) (10). The remaining populations are small and very localised, and are vulnerable to habitat disturbance, fire, collection by visitors, and to predators reaching the last remaining island populations (4) (7). The population on the mainland at Pukerua Bay is particularly vulnerable, and under constant threat from predators and fire (7). Attempts at habitat restoration here are complex; for example, removal of grazing animals and re-vegetation attempts in the past increased rodent populations and consequently increased predation on Whitaker’s skink (11). Whitaker’s skink may be particularly vulnerable to predation and habitat loss because of its relatively large size, long life span, low rate of reproduction, and precise temperature and habitat requirements, as well as the fact that it is most active at the same time of day as its rodent predators (11) (12). The low reproductive rate of this and other New Zealand skinks (7) (9) may also mean that populations take a long time to recover from any losses.

Whitaker’s skink has been the subject of two recovery plans, which set out objectives for the conservation of this and other related skinks. The first, published in 1992, focused on ecological restoration and on the eradication of rodents from large islands, and led to the establishment of the three new populations of Whitaker’s skinks on Korapuki, Stanley and Red Mercury Islands (7) (8). The second recovery plan, in 1999, included in its objectives the periodic assessment of the new populations, continuing pest control and preventing predators from reaching these islands, management of the vulnerable population at Pukerua Bay, as well as further increasing the number of populations and the area the species occupies. Plans to breed the species in captivity have had limited success (7), and have been complicated by hybridisation between the genetically distinct Pukerua Bay and island populations (13). Management of Whitaker’s skink at Pukerua Bay may include further attempts at improving habitat quality (8) (12), as well as investigating the possibility of constructing a mammal-proof fence to protect the skinks from predators (11).

For more information on the conservation of Whitaker’s skink and other New Zealand lizards, see:

New Zealand Department of Conservation - Cyclodina skink:
http://www.doc.govt.nz/conservation/native-animals/reptiles-and-frogs/lizards/cyclodina-skink/

New Zealand Herpetological Society:
http://www.reptiles.org.nz/

Authenticated (29/04/09) by Dr David Towns, New Zealand Department of Conservation.

  1. IUCN Red List (December, 2009)
    http://www.iucnredlist.org