Oligosoma auroraense

Hawke's Bay skink

Oligosoma auroraense
(Melzer et al., 2019)

Hawke's Bay skink (Cape Kidnappers). <a href="https://www.instagram.com/nickharker.nz/">© Nick Harker</a>
Image attribution
Hawke's Bay skink (Cape Kidnappers). © Nick Harker
Herpetofaunal category
NZ Skinks
Species complex
Conservation Status
Threatened - Nationally Vulnerable
Previous scientific names
Oligosoma aff. infrapunctatum "Hawke's Bay",
Oligosoma infrapunctatum,
Leiolopisma infrapunctatum.
Common names
Hawke's Bay skink

Length: SVL up to 100mm, with the tail being longer than the body length

Weight: up to 23 grams

Description

A beautiful, and robust species belonging to the speckled skink complex, Hawke's Bay skinks along with several other species in the speckled skink complex are amongst the largest skink species that still survive on the North Island mainland (at around 90mm SVL). 

Hawke's Bay skinks are light to dark-brown dorsally with black and cream speckling, they often exhibit a dark dorsal stripe, but this may be absent or broken in some individuals. Dark brown lateral stripes with interior cream flecking are present, these are directly bordered by cream-coloured dorsolateral stripes, with the lower stripe breaking up into brown and cream blotching towards the lower surfaces. The lower surfaces are cream to pale yellow with dark brown to black flecking. Melanistic specimens have been recorded appearing dark grey or blue-grey in colouration. 

Hawke's Bay skinks are distinctively patterned and only likely to be confused with the often much smaller northern grass skink (Oligosoma polychroma) with which it co-occurs. Young animals may be confused, but in general Hawke's Bay skink are much larger / more robust, and exhibit more distinct speckling on the dorsal surfaces.

Life expectancy

Unknown

Distribution

Restricted to central Hawke's Bay, particularly the Cape Kidnappers area, but may occur further afield. 

Ecology and habitat

Hawke's Bay skinks are diurnal and strongly heliothermic. They will sunbask, but often cryptically near cover. 

They occur in a range of habitats including dune systems, shrubland, scrub, pasture, and the edges of coastal forest. When not active, foraging or basking, Hawke's Bay skinks take refuge on the ground under rocks, logs, driftwood, or in dense vegetation. They are known to reach densities of 880-990 per hectare in exotic grassland (Dent, 2016).

Social structure

Little is known about the social structure of Hawke's Bay skinks, though they are considered to be solitary.

Breeding biology

Largely unknown, but they may be similar to other members of the speckled skink complex e.g. gravid during spring-summer, and give birth from December to March. 

Diet

The diet of Hawke's Bay skinks includes a wide range of invertebrates, and the berries / fruit of native species.

Disease

Unknown

Conservation strategy

Hawke's Bay skinks are regarded as Threatened - Nationally Vulnerable. They occur within Cape Sanctuary (Cape Kidnappers), which is enclosed by a pest-proof fence but are still exposed to mouse predation within. The range of this species extends slightly outside the confines of the pest-proof fence, but in those areas, they are exposed to the full suite of mammalian pest species. It is likely that this species would benefit from translocations to nearby pest-free islands such as Te-Motu-o-Kura / Bare Island.

Interesting notes

Hawke's Bay skinks are members of the speckled skink cryptic species complex - a group of related taxa with similar morphology that were previously regarded as one highly variable species (Oligosoma infrapunctatum).

References

Dent, E. (2016) The impacts of an introduced mammalian predator (Mus musculus) on tree weta (Hemideina trewicki) and skinks (Oligosoma polychroma, Oligosoma infrapunctatum and Oligosoma lineoocellatum) in Cape Sanctuary, Hawkes Bay. Unpublished MS thesis, Victoria University of Wellington, Wellington, 84 pp.

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.

Melzer, S., Hitchmough, R. H., Bell, T., Chapple, D. G., Patterson, G. B. (2019). Lost and Found: Taxonomic revision of the speckled skink (Oligosoma infrapunctatum; Reptilia; Scincidae) species complex from New Zealand reveals a potential cryptic extinction, resurrection of two species, and description of three new species. Zootaxa, 4623 (3), 441–484. doi:https://doi.org/10.11646/zootaxa.4623.3.2

van Winkel, D., Baling, M. & Hitchmough, R. (2018). Reptiles and Amphibians of New Zealand: A Field Guide. Auckland: Auckland University Press, 376 pp.