Animal Species:Common Blue-tongue Skink - Tiliqua scincoides

Common Blue-tongue Skinks are a large-bodied lizard in the family Scincidae. Australia has several species of Blue-tongue, the Common Blue-tongue is the most commonly encountered by people and is one of the most iconic Australian reptiles. The Common Blue-tongue is a single species with two colour forms that are often referred to by different common names. The smaller lizards on the east coast are called Eastern Blue-tongue Skinks and the larger, yellower animals northern Australia are called Northern Blue-tongue Skinks.

Eastern Blue-tongue - Tiliqua scincoides

Eastern Blue-tongue - Tiliqua scincoides
Photographer: Stephen Mahony © Stephen Mahony

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Standard Common Name

Eastern Blue-tongue Skink, Northern Blue-tongue Skink

Alternative Name/s

Blue-tongue Lizard, Bluey

Number of species

One species with two 'sub-species'

Identification

Eastern Blue-tongue Skink:

Length- 600mm total, 300mm body.
Description- the Eastern Blue-tongue is a long and robust skink. This species can come in a large variety of colours but is overall silvery-grey or white with broad dark brown or blackish bands across the back and tail. Sometimes bright flushes of yellow or orange can be present, usually on the skinks sides. Individuals from coastal areas usually have a black stripe between the eye and the ear which can extend backwards along the neck.

Northern Blue-tongue Skink:

Length- 650mm total, 380mm body.
Description- the Northern Blue-tongue is a long and robust skink. It is variable, but generally with vague light brown and darker brown bands on the back, and stronger bands on the side and tail. It is pale grey below extending up the lower side of the animal. It lacks a thick black stripe between the eye and the neck.

Distribution

The Eastern Blue-tongue extends along the coast and semi-arid inland areas from about Adelaide South Australia, through Victoria, NSW and Queensland.

The Northern Blue-tongue extends from northern Queensland across the top end of Australia including the Northern Territory and the Kimberley of Western Australia.

Habitat

In the bush, Common Blue-tongues inhabit open areas including woodlands and grasslands with plenty of ground cover such as tussock grasses, rocks or logs under which they shelter at night or during cold periods.
Within urban environments Common Blue-tongues have adapted to shelter under a variety of human debris (tin, tiles), garden plants, or buildings and are common inhabitants of many suburban yards in Eastern Australia.

Like all lizards, Blue-tongues do not produce their own body heat, but emerge from hiding places early on warm mornings to bask partially hidden in a sunny spot. Once warmed to their active temperature of 30-35°C they move around to forage.

Feeding and Diet

Common Blue-tongues are omnivores, meaning they eat a wide variety of both plants and animals. Common Blue-tongues are not very agile and mainly eat slow moving prey such as snails and slugs which they can crush with their strong jaws. They also eat many plants naturally including low growing flowers, fleshy leaves and some fruits.

Other behaviours and adaptations

When threatened, Common Blue-tongues 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, Common Blue-tongues may hiss and flatten out the body, to make themselves look bigger. A frightened Blue-tongue may bite if it is picked up.

If handled roughly by their tail, Common Blue-tongues, particularly young ones, may drop their tail. The tail stump rapidly heals and a shorter regenerated tail grows back after a time.

Mating and reproduction

Common Blue-tongues live alone for most of the year, but between September and November males pursue females and mating occurs. At this time, males may fight aggressively among themselves. Mating may be rough, with females carrying scrape marks from the male's teeth. The female Common Blue-tongue then gives birth between December and January. The Common Blue-tongue is able to breed every year if it has sufficient food but other species of Blue-tongue often skip a year.

Female Blue-tongues do not lay eggs, instead giving birth to live young. The embryos develop in the female's oviduct with the help of a placenta, which is as well-developed as that of many mammals. When the young are born, they are covered in a placental membrane, which they eat. Within a few days, they shed their skin for the first time and are ready to look after themselves, dispersing into the bush.

Of all the Blue-tongues, the Common Blue-tongue has the largest litters and the smallest young; up to 19 (but usually about 10) young are born, each measuring 130-140mm in total length and weighing 10-20g.
Common Blue-tongues probably become adults at about three years of age when they have a total length of about 400mm. Common Blue-tongues are long-lived. In captivity, they are known to live for at least 20 years.

Predators, Parasites and Diseases

Reptile ticks and mites are commonly found on Blue-tongues; 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 Blue-tongues and may sometimes be seen in faecal pellets. Again, these worms normally only parasitise reptiles.

In the bush the major predators of Common Blue-tongues are large predatory birds (such as Brown Falcons and kookaburras), large snakes (including the Eastern Brown Snake, Red-bellied Black Snake and Mulga Snake) and other larger lizards (Lace Monitors). Feral cats and dogs also eat Blue-tongues.

Young Blue-tongues 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. Adult Blue-tongues may be killed by large dogs, although the thick bony scales of the adults protect them from many animal bites.

Conservation Status

Common Blue-tongue Lizards are not listed as threatened. They are common in many suburban and bushland areas.

The Northern Blue-tongue may face a substantial threat from the invasive Cane Toad (Rhinella marina) which has negatively impacted populations in many areas.
Eastern Blue-tongue lizards are also negatively affected in backyards by attacks from dogs, or cats which kill many individuals. A further threat is snail poison, which may seriously harm or kill any Blue-tongue that eats a poisoned snail.

We are lucky to have this large and beautiful iconic species within our yards and it is our job to help keep them safe from our backyard pets and poison.

Economic/social impacts

The Common Blue-tongue Lizard is an iconic Australian species. It is commonly used in documentaries on Australian wildlife, maintaining a high presence in tourism advertisement. The Common Blue-tongue also appears on many regional or town welcome signs across Australia and has even made its way into commercial branding, such as that of alcohol.

Danger to humans and first aid

A bite from an adult Blue-tongue can cause pain, break the skin and leave a bruise but they are not venomous and have no long-term effects.

Classification

Species:
scincoides
Genus:
Tiliqua
Family:
Scincidae
Order:
Squamata
Subclass:
Lepidosauria
Class:
Reptilia
Phylum:
Chordata
Kingdom:
Animalia

What does this mean?

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.

 


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