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Oligosoma acrinasum

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA REPTILIA SQUAMATA SCINCIDAE

Scientific Name: Oligosoma acrinasum
Species Authority: (Hardy, 1977)
Common Name(s):
English Fiordland Skink
Synonym(s):
Girardiscincus acrinasum (Hardy, 1977)
Leiolopisma acrinasum Hardy, 1977

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2010
Date Assessed: 2009-06-30
Assessor(s): Chapple, D.G.
Reviewer(s): Böhm, M., Collen, B. & Ram, M. (Sampled Red List Index Coordinating Team)
Contributor(s): De Silva, R., Milligan, H.T., Wearn, O.R., Wren, S., Zamin, T., Sears, J., Wilson, P., Lewis, S., Lintott, P. & Powney, G.
Justification:
Oligosoma acrinasum has been assessed as Near Threatened. This species is found on a number of islands in the Fiordland archipelago, with an extent of occurrence of <20,000 km². Its distribution is considered to be severely fragmented, however it is found in more than ten locations and is currently only threatened by introduced species, primarily the Norway rat, on certain islands in part of its range, with the remained well-managed and monitored frequently. With further invasive species control and management, and evidence that the global population is stable, this species may be listed as Least Concern in the future.

Geographic Range [top]

Range Description: This species is endemic to New Zealand, known from the Fiordland coastline, mostly on islands (Atlas of Amphibians and Reptiles of New Zealand 2010).  It was reported on around 40 small islands off the south-west Fiordland coast and one adjacent mainland site (Gill & Whitaker 2001), between Nancy Sound and Dusky Sound. It has been recorded in the western-most island of each of the Seal Islands and Gilbert Islands groups at the entrance to Breaksea Sound, Fiordland (Hardy 1977), and was reintroduced to HaweaIsland, Breaksea Sound, Fiordland in 1988 (Thomas & Whitaker 1995). It is also known from Breaksea Island (Thomas and Whitaker 1995), which it naturally recolonized from a stack 100 m offshore following eradication of Norway rats in 1988 (Thomas pers. comm., Taylor and Thomas 1993, Towns 1994). Due to its occurrence mainly on islands, its distribution is considered to be severely fragmented (D. Chapple pers. comm. 2010).

In 1977, Hardy stated that little intensive collecting had occurred on the west coast of the South Island and therefore the distribution would have been less restricted than known at the time. The current distribution, however, is considered to be relictual, since previously the species would have almost certainly occurred in high numbers throughout coastal Fiordland (Thomas and Whitaker 1995).
Countries:
Native:
New Zealand
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is listed to have a Recovering population (Hitchmough et al. 2005).  It is considered abundant to extremely abundant in areas free from mammalian predators; conversely it is sparse, often to the point of extirpation in areas with mammalian predators (Atlas of Amphibians and Reptiles of New Zealand 2010).
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: This coastal species inhabits exposed rocky shoreline platforms and boulder beaches, cracked and creviced foreshore rocks and boulder beaches on open coast (Thomas and Whitaker 1995). This species seeks cover in rocky cracks and crevices and may enter splash pools to escape danger (Gill and Whitaker 2001). Occasionally it ventures into the adjacent zone of supra-littoral vegetation. Individuals have been seen under coastal shrub only twice and both in places where this vegetation joined the shoreline rocks (D. Chapple, pers. comm). This species is diurnal, and an extremely avid sun-basker (Gill and Whitaker 2001). It is an adept swimmer and apparently has a high tolerance to salt water (Thomas 1985, Towns 1994).

This species feeds on a variety of invertebrates. It has been observed taking prey ranging in size from blackflies (<3 mm) to blowflies (12 mm). Chitinous invertebrate fragments from 20 droppings included small snails, amphipods, isopods, millipedes, spiders, harvestmen, weevils, flies, wasps and caterpillars (Thomas 1985).
Systems: Terrestrial

Threats [top]

Major Threat(s): This species had not been observed on islands colonized by Norway rats, however, it is known to have naturally recolonized Breaksea Island from nearby rocky outcrops once the rats had been exterminated (Thomas and Whittaker 1995).

The native skinks of New Zealand are threatened primarily by the impacts of introduced species. Goats, deer and possum are known to alter the vegetation structure (Towns et al. 2002, Atkinson and Towns 2001), while a variety of birds and mammals are known to prey on skinks. Such predators include magpies, Australasian harriers, New Zealand falcons, feral cats, ferrets, stoats, weasels, ship rats, Norway rats, mice and European hedgehogs (Tocher 2006).

Conservation Actions [top]

Conservation Actions: This species is listed as Range Restricted with a Recovering population due to Human Impacts (Hitchmough et al. 2005). The entire range of this species is contained within the Fiordland National Park. Population monitoring is recommended to ensure this species is in fact recovering, and measures to keep the island habitat free of invasive alien species need to be continued.

Citation: Chapple, D.G. 2010. Oligosoma acrinasum. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 01 September 2014.
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