Case study: Green iguana – A new exotic found in the wild

Incursions of exotic (non-native) species create the risk of new pest populations establishing that significantly impact our environment, economy or society. The green iguana is a lizard species originating from South and Central America that has become established in over 14 other locations overseas.

Potential impacts include burrowing (undermining infrastructure such as railway lines), competing for nesting hollows, dispersing weed seeds, posing an airstrike hazard, carrying exotic diseases and biting people. The green iguana was recently assessed as having an extreme risk of establishing in Australia because there are large areas of suitable climate in our northern and coastal regions.

Iguanas, and indeed all exotic reptiles, are generally not permitted to be kept as pets in Australia. However, recent evidence indicates that iguanas are held illegally in Australia and they have also appeared at Australia’s border on multiple occasions. Since 1999, Customs has seized at least five iguanas in smuggling incidents and Australian Quarantine Inspection Service (AQIS) has intercepted at least one as an unintentional stowaway in cargo. At least 17 iguanas have been confiscated by authorities from illegal private keeping in the past 10 years.

This case study describes an incident in April 2011 when a green iguana was sighted in the wild for the first time in Australia.

What happened

A member of the public sighted an unusual green lizard (see above) in the water while she was kayaking down a tributary of the Ross River in Townsville, Queensland. Suspecting it was an exotic iguana, she took a photo of the animal, which swam away and couldn’t be relocated. The lizard in the photo was subsequently identified by researchers at James Cook University and CSIRO as a green iguana.

A team of volunteers supervised by staff from Biosecurity Queensland, James Cook University and CSIRO searched the river and nearby botanic gardens for the next few days. The iguana was eventually spotted several days later and 20 metres from where it was originally seen. It was climbing up a tree overhanging the river. A person lifted in a basket via crane retrieved the iguana using a pole and noose.

The lizard was a young adult female in good condition and had been eating mainly figs. No other green iguanas were observed during the surveys, so it was unlikely to be part of a larger wild population.

In accordance with the Environment Protection and Biodiversity Conservation Act 1999, the iguana was euthanased soon after capture, and destroyed to prevent risks of spreading disease.

The iguana was likely someone’s pet that had escaped or been released. It was very docile and had scars on its nose (often found in captive reptiles that rub their noses against their enclosures).


The discovery of a green iguana in the wild in Queensland demonstrates the risk to Australia of exotic species becoming established here if left unchecked. This iguana was presumed to be an escaped or released illegal pet.

Pets held legally or illegally both present a potential pest threat if they get into the environment in sufficient numbers. Fortunately, in this instance there was only a single animal involved and the quick action of the person who sighted this iguana led to its capture.

This case emphasises the importance of educating the public about responsible pet ownership and particularly the consequences of high-risk animals being released or escaping. The more animals that enter the wild, the more chance there is of a pest population establishing, which could impact on our native species, our agriculture or our society. One of the critical factors in preventing new pests establishing is to make sure high-risk species are kept securely or surrendered to appropriate authorities.

Anyone who sees an unusual animal in the wild should report it to their local council or phone 1800 675 888.

Author Invasive Animals CRC
Year 2012
Publisher Invasive Animals CRC
Pages 2
ISBN/ISSN PestSmart code: GENCS1
Region QLD
Documents PestSmart Case Study: A new exotic found in the wild [410 kb PDF]
Links PestSmart New and Emerging page: