Plague skinks: What's in a name?
While the impacts of introduced mammals on our native ecosystems are widely known, what about introduced lizards? Zealandia post-doctoral researcher Christopher Woolley shares his thoughts on the plague skink, an introduced skink from Australia that may have a big impact on our native lizards.
Delicate in its slender form and lustrous in its rainbow iridescence, these are the characteristics which lend the skink Lampropholis delicata its common names in its native range of eastern Australia. The rainbow skink (also known as the delicate skink) is widespread from Brisbane to Tasmania where it is one of the most abundant skink species in urban areas.
In the context of Australian ecosystems, the plague skink likely relies on its short time to sexual maturity (half that of many NZ native skinks) and large annual production of offspring (clutches of up to eight eggs) to ensure survival in the face of competition and predation by larger reptiles. Outside its native range, these traits allow it to rapidly achieve high population numbers; and it is for this characteristic that in Aotearoa it is called the plague skink. Use of this name is shared by other Pacific Islands, such as Lord Howe and Hawai’i, where the species has become established after being introduced.
Species that have a high reproductive output, especially those who lay eggs, make excellent invaders and in Aotearoa, the invasion is on-going. The species arrived in Tāmaki Makaurau/Auckland in the 1960s and since then has spread through the northern half of Te Ika a Maui/North Island including conservation-sensitive offshore islands. It has also established isolated populations in Palmerston North, Foxton Beach, and several other sites, and in 2018 an established population was identified in Blenheim in Te Wai Pounamu/South Island. Climate modelling shows the species could establish populations across much of Te Wai Pounamu.
Plague skink. No doubt the name is apt, but is there a risk to labelling an animal a denigrating name? This elegant, multicoloured skink may be the only lizard (of NZ’s more than 126 species) that many New Zealanders experience in their day- to- day lives. I’m loath for this relationship to be a negative one given the lacking public awareness of lizards.
I do wonder how an animal’s name influences the way people feel about it. Would a sacred kingfisher by any other name be so revered? A welcome swallow so appreciated? A spotless crake so… clean? I jest, but only in part. I am conscious of diminishing the appreciation of any species by the connotations of its name, irrespective of its ecological impacts. Equally though, I would not want to diminish the risks that this invasive species brings to New Zealand ecosystems.
While plague skinks have been established in northern Aotearoa for a while, the impacts of this species on coexisting native lizard populations are still unclear. Research has demonstrated sufficient diet and habitat overlaps with native skinks to suggest potential for resource competition, and the threat of disease transmission is largely unknown. On top of these direct impacts, there is potential for high numbers of plague skinks to drive up numbers of skink-specialised predators, which in turn will predate native species. Any small reduction in survival odds for populations of native skinks caused by a new competitor or disease adds to the numerous threats already driving declines for many species.
Lampropholis delicata, the plague skink, represents a current challenge for New Zealand conservation and we must take every precaution. As limited tools are available to eradicate populations, preventing the spread is reliant on biosecurity. If naming this species for its negative impacts assists in this mission by encouraging vigilance among the public, then I support this. But we should not let this lessen our respect for yet another intriguing and successful creature caught unwittingly in a world dominated by human objectives.
Christopher K. Woolley is a post-doctoral researcher at Zealandia - Te Māra a Tane and an adjunct researcher at Te Herenga Waka - Victoria University of Wellington. His research focusses on herpetology, urban ecology, and human dimensions in biodiversity conservation.
Photo: Plague skink by Xander T, via Wikimedia Commons