The battle against plague skinks will not extend to Waiheke Island.

Plague skinks are being eradicated from Great Barrier Island, but are too well established to tackle on Waiheke Island.

Chickens are being tried for the first time as a means to control a small number of plague skinks found around Tryphena Wharf on Great Barrier Island.

Auckland Council biosecurity advisor Deryn Dromgoole said fumigation and intensive trapping successfully eradicated a recent incursion of plague skinks on Rakino Island.

However, the Australian lizard was first identified on Waiheke Island in 2014 and was already too widespread to eliminate, she said.

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"Efforts and limited resources are instead being put towards preventing their spread to pest free areas of the region like Aotea, Rakino and other islands," Dromgoole said.

Given plague skinks are prolific breeders, it is likely numbers are increasing on Waiheke.

"Numbers are difficult to determine, but there are definite hot spots in Ostend, Palm Beach, Little Oneroa and Onetangi," Dromgoole said.

Plague skinks are the only introduced reptile to have become established in New Zealand.

They arrived in South Auckland from Australia in the 1960s and human activity has enabled them to spread steadily through the northern half of the North Island.

"Plague skinks can compete aggressively with our native lizards and skinks for space and resources, which can cause displacement and decline of native populations," Dromgoole said.

The Ministry for Primary Industries classified the plague skink, also known as the rainbow skink, as an unwanted organism in 2010.

Dromgoole said attempts to eliminate the pest reptile should not be attempted without expert guidance, because identification and management is difficult.

However, people can help prevent them spreading, by ensuring shoes, landscape and building materials, and other equipment is free of pests before it is transported.

Potted plants pose a particular risk and can be soaked in water for two minutes, so plague skink eggs float to the surface.

Plague skinks are slender and about eight centimetres long, greyish-brown, with an iridescent sheen visible at times.

Native copper skinks look similar, but are stockier and lack a rainbow sheen.

While native skinks hide, plague skinks can be found out in the sun and in warm sites with lots of stones and crevices, Dromgoole said.