Plague (rainbow) skink Lampropholis delicata

ABOUT THIS PEST

KEY CLUES

Distinctive features: Plague skinks have one large scale on the top of their head, whereas New Zealand native skinks have two smaller scales. Most (but not all individuals) have a rainbow-coloured iridescent shine in sunlight.  Extremely long, slender tail, that is longer than the length of the body.

Size: Adults are approximately 36-55 mm from snout to vent (base of the tail). 

Droppings: Small, dark (brown/black) pellets with white tip, approximately 2-5mm long.

Footprints: Can be distinguished from indigenous skink prints via the number of toe segments (known as lamellae) on front 4th toe (11-13 lamellae) and rear 4th toe (21-23 lamellae).

Vegetation damage: May forage on small fruits in ground tier vegetation.

Distribution: Established populations throughout much of the North Island including in Auckland, Northland, Waikato, Bay of Plenty, Coromandel, Wanganui, Palmerston North and the Manawatu.

WHY ARE PLAGUE (RAINBOW) SKINK PESTS?

Unwanted Organism

Plague (rainbow) skink is classified as an Unwanted Organism in New Zealand because of their rapid population growth and because they are accidental imports to New Zealand.  If you think you have seen a plague skink outside of the area where they are currently known, phone the Ministry for Primary Industries Pests and Diseases Hotline 0800 80 99 66.

Ecological impacts

Plague skinks (previously known as rainbow skinks) arrived in New Zealand in the late 1960s, but only became classified as an Unwanted Organism in recent years, and removed from the Wildlife Act in 2010. Their ecological impacts are largely unknown.  Their greatest impact is suspected to be competition with native lizards for resources including food and habitat. Plague skinks prey on invertebrates and are very good at settling in and making a home in almost any kind of habitat. They are excellent stowaways and have established populations on several offshore islands in Auckland’s Hauraki Gulf, which are home to many native lizard species no longer present on the mainland. Plague skinks on these islands will not only be competitors but may pose additional risk by passing on diseases from the mainland that the native lizards have not come into contact with.

Plague skink populations reach very high densities, providing a food resource for mammalian predators such as rats, hedgehogs, mustelids and feral cats. A good food supply may lead to increased numbers of those predators which, in turn, may increase the risk of native species being killed.

Other impacts

Plague skinks tend to thrive in urban areas.  As their populations have increased, more and more people in cities such as Auckland have reported plague skinks entering their homes and taking up residence. This poses a potential risk to human health, as lizards are known to be carriers of diseases including salmonella and cryptosporidium.

Read more about plague (rainbow) skink


Droppings

Separate

Lizard droppings (also known as ‘scat’) typically come in the form of a small dark (brown/black) cylindrical pellet with a small white tip that is uric acid. Dropping size can vary depending on the size of prey that has been consumed but typically may range between approximately 2 and 5 mm long.

Can be confused with:

Plague skink droppings are virtually indistinguishable from those of other native skinks of similar size, including the white tip of uric acid. Plague skink droppings can also be confused with mouse droppings, small bird droppings or even wētā droppings but the important point of difference is that, like birds, lizards excrete uric acid which forms the small white tip at the end of the scat. 

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Footprints and Tracks

Paws and feet

Plague skinks may be identified via the segments on their toes, which are called ‘lamellae’: – between 11-13 lamellae on the 4th toes of the front feet and between 21-23 on the 4th toes of the rear feet. As lizards can be hard to capture, pre-inked tracking cards serve as a good way for wildlife managers to detect and identify lizard species. A good foot impression on the ink provides a way of counting lamellae and, therefore, identifying which species may be present.

Can be confused with:

Copper skink tracksNative skinks, particularly copper skinks, look very similar to plague skinks. In juvenile and sub-adult life stages they may have very similar colouring, body shape and size. As there are few tell-tale signs to distinguish between plague skinks and native skinks, the lamellae count of the front and rear 4th toe can be very helpful, as native skinks have fewer than 9 lamellae on the front 4th toe and fewer than 21 lamellae on the rear 4th toe.

Dens and nests

Unlike most native skinks, which give birth to live young, plague skinks lay eggs (that is, they are oviparous).  Each female may lay 3-7 eggs, several times per year, but commonly between September and April.  Eggs are oval shaped and typically less than 10 mm long and 5 mm in diameter.  The shell is smooth, leathery and may have a pinkish-coloured hue beneath the surface.  Within a population of plague skinks, many of the females may lay their eggs in the same place – this is called a ‘communal clutch’.  The largest communal clutch recorded in New Zealand contained almost 3000 eggs. 

Eggs may be found almost anywhere but are commonly found in gardens beneath pot plants, in compost, under sheets of corrugated iron and anywhere that may provide protection for the eggs until they hatch, approximately 40-60 days after being laid.

Can be confused with:

There is one native New Zealand egg-laying skink species, the Suter’s skink, also known as the diving skink or the egg-laying skink. Its eggs are unlikely to be confused with those of the plague skink, as Suter’s skinks are range-restricted to only a few North Island mainland and island locations, and primarily inhabit boulder beaches and rocky platforms within the intertidal splash zones. Therefore, this species is unlikely to be found in places where plague skinks occur.

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Vegetation Damage

Fruits and Flowers

In urban gardens plague skinks have been known to feed on small fruits including strawberries and blackberries, although they prefer to feed on a wide variety of invertebrates, acting as both predators and scavengers. We have no information as to what their dmage might look like.

Can be confused with:

Similar types of fruit damage could be caused by other species of skink and by invertebrates.

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Kill Sign

Insects or snails (invertebrate)

Plague skinks are not fussy eaters and will readily consume a wide variety of insects including moths, small beetles, amphipods, spiders, slaters, crickets and snails.  It is not known what kill sign is left behind.  Often they eat the entire invertebrate.

Can be confused with:

Other species of skink and invertebrates could cause similar damage.

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Other Clues

Body covering

 Plague skinks are covered in scales. Plague skinks have one large scale on the top of their head, known as a fronto-parietal head scale. It is located on the top of the head directly between the eye sockets. It is the most important factor for distinguishing plague skinks from New Zealand native skinks, which have two smaller scales instead.In the plague skink it is a single scale shaped like a diamond but in all New Zealand native skinks, it is in two parts, which together look a little like an upside-down heart.

Plague skinks (Lampropholis delicata) were originally named the ‘rainbow skink’ in New Zealand due to the rainbow-coloured sheen that the scales of some adults display at certain angles; however, that name is now reserved for an African species of skink.

Can be confused with:

confusedwith copper plague 2sqx100

Plague skinks can look similar to some native skinks, especially copper skinks. Copper skinks are a similar colour to plague skinks but their scales don’t have the rainbow hues and they have a divided front-parietal head scale.

 

Distribution

There are established populations of plague skinks throughout much of the North Island including in Auckland, Northland, Waikato, Bay of Plenty, Coromandel, Wanganui, Palmerston North and the Manawatu.

Can be confused with:

Plague skinks may be confused with a number of native skink species that are found in the same locations within New Zealand.  See body covering clue for details of the main distinguishing feature, the head scale.

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MORE ABOUT PLAGUE (RAINBOW) SKINK

Origin

Australia.

Description

The plague skink is a small, typically brown lizard that is also known as the ‘rainbow skink’ due to most individuals having a rainbow-coloured iridescent shine on their backs and tails when viewed at certain angles.  Plague skinks lay eggs, in contrast to our native skinks, all except one species of which give birth to live young. 

Size and weight

Plague skink hatchlings range between 15 and 19 mm in body length and weigh approximately 0.1 g.  As adults, they may range between 34 and 55 mm in body length and weigh between 0.75 g and 1.65 g.

Behaviour

Plague skinks are typically quite bold and are well established in urban and residential areas that are inhabited by high numbers of predators and people.  Female plague skinks will nest together and sometimes create very large communal clutches of eggs.  Hatchlings are immediately active and begin to search for food.

Diet

Plague skinks are known to both prey on and scavenge on a wide variety of invertebrates including moths, small beetles, amphipods, spiders, slaters, crickets and snails.  In urban gardens, they have been observed foraging on small fruits, such as berries, and thrive in compost environments, foraging on both invertebrates and compost vegetation.

Habitat

Plague skinks are able to inhabit a wide variety of habitats including grasslands, indigenous forest, coastal zones, and urban and industrial environments.

Other

Originally called ‘rainbow skink’ in New Zealand, this species has been re-named ‘plague skink’ due to the plague-like densities it is able to rapidly achieve in a wide variety of habitats.  Also, the previous name was found to be misleading and, in some cases, led to misidentification, because not all individuals of this species display the rainbow-coloured sheen. The name change also prevents confusion with an African species known as the rainbow skink. In their native Australia, they are known as either 'garden skink' or 'delicate skink'.

How to get rid of it

There are no established management or eradication methods at this stage.

FIND MORE INFORMATION IN:

Department of Conservation. (2015). Rainbow Skinks: A Threat to Our Native Fauna.  Retrieved in 2017 from http://www.doc.govt.nz/upload/documents/conservation/threats-and-impacts/animal-pests/Rainbow-skinks-factsheet.pdf.

Miskelly, C. (2017). Plague Skinks invade the Coromandel. Retrieved in 2017 from http://blog.tepapa.govt.nz/2017/01/19/plague-skinks-invade-the-coromandel/

Peace, J.E. (2004). Distribution, Habitat Use, Breeding and Behavioural Ecology of Rainbow Skinks (Lampropholis delicata) in New Zealand. (Unpublished MSc thesis). The University of Auckland, New Zealand.   

Russell, J.C. & Klette, R. (2010). Tracking Small Artists. Retrieved in 2017 from https://researchspace.auckland.ac.nz/bitstream/handle/2292/4359/MItech-TR-44%255B1%255D.pdf%3Fsequence%3D2

Wairepo, J. (2015). Developing Biosecurity Strategies for An Invasive Reptile, the Plague Skink (Lampropholis delicata) on Great Barrier Island. (Unpublished MSc thesis). Massey University, Auckland, New Zealand.