Plague skink

What does it look like?

Plague skinks (also known as rainbow skinks) are 3 - 4cm long from the tip of the nose to the hind legs, excluding the long thin tail. They are brown or grey-brown with a dark brown stripe down each side, and an iridescent rainbow, or metallic sheen, when seen in bright light. They look very similar to native skinks but have one large scale on the top of their head, where native skinks have two smaller scales.

Why is it a problem?

The plague skink was accidentally introduced to Auckland from Australia in the 1960s. They are now found in the North Island from Northland to Waikato and the Bay of Plenty, with outlying populations at Whanganui, Palmerston North, and Foxton Beach. There is an established population in Blenheim, and they have been found in Havelock in the Marlborough Sounds.

The natural distribution rate of plague skinks is unknown. The greatest incursion threat to the Hawke’s Bay region is an accidental introduction by humans. Given the vegetation and climate of the Wellington region, a successful incursion is likely, should the opportunity be provided.

Plague skinks can reach high population densities in a relatively short time, maturing in less than half the time of native lizards and laying up to eight eggs three times per year. Most native skinks only breed once per year and may not even start breeding until they are around five years old. All endemic New Zealand lizards except for the egg-laying skink, Oligosoma suteri, give birth to live young.

Plague skinks are known to be generalist feeders and can live in a broad range of habitats, with the potential to out-compete indigenous species. Any vertebrate poison for these skinks would also target native species, making control difficult. They also increase predation pressure on native invertebrates.

Control methods

Preferred habitat
Plague skinks prefer moist areas and are commonly found under vegetation, litter, rocks, and logs. Potting mix in potted plants is a favoured breeding habitat.
They also thrive in urban areas, gardens, commercial areas, industrial sites, garden centres, and waste ground. These skinks will frequently enter freight and shipping containers.

Prevention
If you travel from an area that has plague skinks, and wish to relocate any equipment, goods, or other freight to or through the Hawke’s Bay region, thoroughly check your personal belongings for plague skinks or their eggs before departure.
You may find communal nests of 20-100 small white eggs, 8-10 mm long, oval in shape, with a tough leathery shell.
It's common for them to lay their eggs in the soil of potted plants, so if you are shifting plants, check for any clusters of small white eggs, especially if plants are to be used in restoration projects, such as on off-shore islands or at key ecosystems on the mainland.
If a domestic cat brings in a live or dead skink which is suspected to be a plague skink, keep the skink in a jar for identification.

Awareness
DOC and MPI are monitoring the distribution of plague skinks and raising public awareness of how to limit the spread of this invasive species.
If you suspect you have found or seen a plague skink, or their eggs, in addition to contacting DOC or MPI via their hotlines, please add your observation to iNaturalist.

Related links

• Department of Conservation
• iNaturalist
• Ministry for Primary Industries
• The Reptile Database
• Unwanted Organisms Register