10 Jun 2016

Critter of the Week

From Afternoons, 1:35 pm on 10 June 2016

DOC's Endangered Species Ambassador, Nicola Toki presents... the cobble skink - last known to only be found on the beach behind the Granity pub on the West Coast

Cobble skinks were only recently discovered (2015) as a distinct species.  They live in the ‘cobbles’ (beach stones) on West Coast beaches, but due to a wide range of complex interations, and their very specific habitat requirements, were last known to only be found on the beach behind the Granity pub to the shoreline. 

However, increasing storm surges, possible sea level rise, and the invasion of weeds (which glues the cobbles together, and creates a bank, rather than allowing storm surges to throw the stones back up on the beach), as well as predators likely picking off skinks from outside the habitat, reducing the ability of this species to be supplemented with numbers, has meant that by the time we checked again a couple of months ago, there were likely only 30-40 individuals left.

This (and the knowledge that there were some big storms on the horizon) led to an emergency evacuation situation involving a range of experts and rangers, not to mention the kind folk at Auckland Zoo who offered to house this entire species until the Department of Conservation could work out where to put them again. 

The Cobble skink is known only from a short stretch of coast at Granity, north of Westport. When it was discovered in 2007 it was locally abundant, although already extremely restricted in distribution. When surveys were undertaken in January 2015 by 3 separate groups of herpetologists, it was apparent to all that the cobble skink population had declined significantly and rapidly, and that much habitat had been lost.  The Herpetologists agreed these skinks seem to be easy to catch.

The Cobble skink was assessed in the NZ Threat Classification System in late 2015 as Nationally Critical on the basis that it occupied less than 1 ha of habitat.  It had undergone a severe observed decline.

  1. The cobble skink shows a strong specialization to the cobble stone/pohuehue habitat association.
  2. The cobble/pohuehue habitat was probably once a vast system along much of this coastline, and remnants still exist from south of Jones Creek in the south to Ngakawau in the north
  3. This entire stretch of coastline is eroding rapidly. A January 2016 Niwa report to the West Coast Regional Council states that the section of coast at Granity where the current population exists is retreating at a rate of 60-80cm per year, but the locals point out that one-off events like cyclones can take even bigger bites

Cobble skinks have large eyes, thought to be useful for burrowing between the cobbles.  They are small, only six cm long.


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