Shingleback Lizard

Introduction

The bulkiest of the blue-tongues, the Shingleback Lizard are common on the plains west of the Great Dividing Range where rainfall is low and throughout the semi-arid habitats of inland Australia as well as coastal parts of Western Australia and South Australia.

Identification

Shinglebacks in New South Wales are usually dark brown all over, with or without yellow spots. The belly of blue-tongues is usually pale with darker variegations. The eye is small and reddish-brown to grey. The tongue is dark blue and the lining of the mouth is bright pink.

The Shingleback has a very large head, a very short blunt tail and large rough scales. Males have a proportionally larger head and stockier body than females but females grow slightly bigger than males.

Habitat

Shinglebacks usually live in open country with lots of ground cover such as tussocky grasses or leaf litter. They shelter at night among leaf litter or under large objects on the ground such as rocks and logs. Early in the morning the lizards emerge to bask in sunny areas before foraging for food during the warmer parts of the day. Like all lizards, Shinglebacks do not produce their own body heat, and rely on the warmth of their surroundings to raise their body temperature. Shingleback Lizards maintain a body temperature of about 30°C - 35°C when active. During cold weather they remain inactive, buried deep in their shelter sites, but on sunny days they may emerge to bask.

Distribution

Shinglebacks are common and widespread in New South Wales from the western slopes of the Great Dividing Range and do not occur naturally in Sydney.

Feeding and diet

Shinglebacks eat a wide variety of both plants and animals; Shinglebacks eat more plant food than do the other blue-tongues. Shinglebacks are not very agile and the animals they eat are mostly slow-moving. Their teeth are large and they have strong jaw muscles so they can crush snail shells and beetles.

The captive diet for this species at the Australian Museum is provided in three feeds within a period of a week. These consist of a small feed of chopped vegetables on one day, a small serving of kangaroo mince on another day as well two cockroaches, crickets snails for the third feeding. The timing and order of the diet is changed around to simulate natural conditions and prevent stereotypical behaviour (where an animal will have predictable activity patterns and essentially be waiting to be fed). This food is supplemented with calcium and vitamin powder to ensure that a nutritionally balanced diet is provided.

Other behaviours and adaptations

When threatened, Shinglebacks turn towards the threat, open their mouth wide and stick out their broad blue tongue that contrasts vividly with the pink mouth. This display, together with the large size of the head, may frighten off predators. If the threat does not go away, Shinglebacks may hiss and flatten out the body, making themselves look bigger. A frightened Shingleback may bite if it is picked up.

Life history cycle

Female Shinglebacks give birth three to five months after mating, between December and April.

The embryos develop in the female's oviduct with the help of a placenta, which is as well-developed as that of many mammals. At birth, the young eat the placental membranes, and within a few days shed their skin for the first time. The young are ready to look after themselves straight after birth, and disperse within a few days.

The Shingleback has usually only two or three young that measure up to 220 mm in total length and weigh as much as 200 g.

Breeding behaviours

Shingleback Lizards live alone for most of the year, but between September and November reunite as monogmous pairs. Shinglebacks in western New South Wales are often seen crossing roads in pairs, the male following the female. The same pairs may re-form in the mating season over several years.

Predators

Reptile ticks are commonly found on Shinglebacks; they attach under the scales and in the ear canal. They do not normally attach to mammals, and are not known to cause paralysis. A number of nematode worms parasitise large skinks such as Shinglebacks, and may sometimes be seen in faecal pellets. Again, these worms normally only parasitise reptiles.

In the bush the major predators of Shinglebacks are large predatory birds (such as Brown Falcons and Laughing Kookaburras) and large snakes (including the Eastern Brown Snake, Red-bellied Black Snake and Mulga Snake). Feral cats and dogs also eat Shinglebacks.

Young Shingleback Lizards are easy prey for suburban dogs and cats, as well as predatory birds like kookaburras. Most young blue-tongues in suburban gardens probably do not reach adulthood. A few adult Shinglebacks are also killed by large dogs, although the thick bony scales of the adults protect them from many animal bites.

Danger to humans

A bite from an adult Shingleback Lizard can cause pain, break the skin and leave a bruise but there is no venom and hence no long-term ill effect. However the bite site should be cleaned with a mild disinfectant, as with any animal bite.

References

• Cogger, H.G. 1994. Reptiles & Amphibians of Australia. Reed Books, Sydney.
• Ehmann, H. 1992. Encyclopedia of Australian Animals. Reptiles. Australian Museum and Angus & Robertson, Sydney.
• Greer, A.E. 1989. The Biology and Evolution of Australian Lizards. Surrey Beatty & Sons, Sydney.
• Weigel, J. 1988. Care of Australian Reptiles in Captivity. Reptile Keepers' Association, Gosford.
• Wilson, S.K. & Knowles, D.G. 1988. Australia's Reptiles: A Photographic Reference to the Terrestrial Reptiles of Australia. William Collins, Sydney.