Oligosoma whitakeri

Whitaker's skink

Oligosoma whitakeri
(Hardy, 1977)

Whitaker's skink (Ngā Manu Nature Reserve). <a href="https://www.instagram.com/nickharker.nz/">© Nick Harker</a>
Image attribution
Whitaker's skink (Ngā Manu Nature Reserve). © Nick Harker
Herpetofaunal category
NZ Skinks
Species complex
Conservation Status
Threatened - Nationally Endangered
Previous scientific names
Cyclodina whitakeri
Common names
Whitaker's skink

Length: SVL up to 101mm, with the tail being equal to or slightly longer than the body length

Weight: up to 20 grams

Named in honour of the renowned New Zealand herpetologist Anthony (Tony) Whitaker.

Description

A large, and highly secretive skink with intricate cream/yellow and black blotching on it's flanks. Whitaker's skinks were formerly widespread in the North Island, but are now one of our rarest lizards.

Dorsal (upper) surface colours range from yellow/brown to dark brown; back covered with light to dark flecks which may be indistinct or very prominent. Flanks cream to yellow or brown, usually heavily mottled with black, particularly on the sides of the neck. This typical flank pattern can also be reversed with a black background colour with pale mottling. Ventral (lower) surfaces: yellow to orange belly, usually unmarked or faintly marked; throat pale grey. Sides and top of tail sometimes have an orange hue. The head is deep set with a short, blunt snout. A pale, black edged tear drop is present beneath each eye. Whitaker’s skink reach SVL (snout-vent-lengths) of 80-101mm. Males weigh up to 20g, and breeding females 25-26g (D. Keall, personal communication, October 18, 2016).

Whitaker’s skinks are similar in appearance to marbled skinks. However, marbled skinks usually have a heavily marked belly. Juvenile Whitaker’s skinks can appear similar to ornate skinks but have more ventral scale rows.

Life expectancy

Individuals have been known to live over 46 years in captivity (D. Keall, personal communication, October 18, 2016).

Distribution

Prior to the arrival of humans and the pests they brought with them, Whitaker’s skinks were widespread in the North Island. Subfossil remains of this species have been found on Motutapu Island near Auckland, in the Waikato region, and to as far south as Wellington.

At the time of their discovery they were only known from three locations: Middle Island (Mercury group) and Castle Island off the Coromandel peninsula; and a small population at Pukerua Bay on the mainland north of Wellington. The small population at Pukerua Bay is now presumed extinct in the wild and a small population is held in captivity as part of a breeding programme 

The species has been translocated from Middle Island to two further islands in the Mercury group: Korapuki Island in 1988, and Red Mercury Island in 1994.

Ecology and habitat

Whitaker’s skinks inhabit leaf litter and seabird burrows in coastal forests and scrub. At Pukerua Bay the species was occupying a coastal boulder bank interspersed with patchy Muehlebeckia sp. vineland.

A crepuscular and nocturnal species which are active at dawn and for several hours after dusk. Whitaker's skinks are active over a very narrow climatic range, with capture rates at Pukerua Bay indicating that the temperature preference for activity is 15-20°C. Gravid females will sun bask.

Social structure

Largely unknown; observations of captive animals indicate that the species prefer to live solitarily (D. Keall, personal communication, October 18, 2016).

Breeding biology

Whitaker’s skinks are ovoviviparous, giving birth to litters of up to 5 young in April.

Diet

Whitaker’s skinks are carnivourous, feeding on prey such as: moths, beetles, spiders, grubs, hoppers, and worms. They are known to forage within seabird burrow complexes and boulder banks.  

Disease

Largely unknown.

Conservation

DOC classify Whitaker’s skinks as ‘nationally endangered’. DOC have a recovery programme in place for the Oligosoma skink group, and a specific recover plan for Whitaker’s skink.

A project is being undertaken by DOC and Friends of Mana Island to capture, breed and relocate a population of vulnerable Whitaker’s skinks from Pukerua Bay to predator free Mana Island. There is some uncertainty and concern about how Whitaker’s skinks might interact with the larger and more aggressive McGregor’s skink (Oligosoma macgregori) which are already present on the Island (subfossils indicate the two species have been sympatric in the past but no longer coexist at the same sites due to relictual distributions.

References

Gill, B.J., & Whitaker, A.H. (2007). New Zealand frogs and reptiles. Auckland: David Bateman Limited.

Hitchmough, R.A., Barr, B., Lettink, M., Monks, J., Reardon, J., Tocher, M., van Winkel, D., Rolfe, J. (2016). Conservation status of New Zealand reptiles, 2015; New Zealand threat classification series 17. Wellington: New Zealand Department of Conservation.

Jewell, T. (2011). A photographic guide to reptiles and amphibians of New Zealand. Auckland: New Holland Publishers Ltd.

Towns, D. (1992). Recovery plan for Whitaker’s skink and robust skink: Threatened species recovery plan series no. 3. Wellington: Department of Conservation.