23 Sept 2019


Dry, warty and incredibly toxic.

Cane toads, Bufo marinus (Rhinella marina), are tough, heavily built amphibians that have developed a bad reputation in Australia. While cane toads aren’t bad (they’re just built that way), they are an invasive species that have wreaked havoc on Australia’s delicate ecosystems and biodiversity.

Since their introduction to Australia, they’ve continued to cause local extinctions of native animals, and they’re marching their way across the country. Local Indigenous rangers tell stories of birds that fall dead from the sky after eating a tasty cane toad.

So, what are these deadly cane toads all about, and how did they get to the land down under? Here are 10 facts:

1. Cane toads are native to South and mainland Central America

They were also introduced to various islands throughout Oceania and the Caribbean, and can also be found in Australia. They’re also known as ‘marine toad’ and ‘giant’ toad.

2. Cane toads were introduced to Australia in 1935

Close up of a cane toad
© Shutterstock / Thomas Bedford / WWF

Why were they introduced in the first place? They were brought to Australia from Hawaii with the intention to control the cane beetle in sugar cane fields in North Queensland. Only 102 cane toads were brought over to be bred, and 2,400 toads were released in 1935.

It seemed like a great idea at first, however, the cane beetles and the cane toads rarely crossed paths. Cane beetles live high on the upper stalks of the cane plant, and cane toads can’t jump that far so they barely had any impact!

3. From 102 cane toads now up to an estimated 200 million cane toads

A knot of cane toad metamorphs
© Travis Child / WWF-Aus

How many cane toads are in Australia? In less than 85 years, the cane toad population has multiplied to epidemic proportions. Now, some scientists estimate that there are more than 200 million cane toads hopping around our continent, wreaking havoc on our ecosystem and expanding across northern Australia at a rate of 50km every year.

4. They’re a delicious - but deadly snack

Cane toads are toxic at all life stages - from eggs to adults. They have large swellings called parotoid glands on each shoulder behind their eardrums This is where they carry their milky-white toxin (known as bufotoxin). Their skin and other glands across their backs are also toxic.

This spells bad news for Australia’s native species, as they haven’t had time to adapt to these toad toxins. One lick or bite can cause native animals to experience rapid heartbeats, excessive salivation, convulsions, paralysis and death.

5. Toad licking can’t actually get you high (sorry!)

Despite popular urban legend that licking cane toads can get you high, this is purely a myth. However, humans can get incredibly ill if the toxin is ingested and if sprayed with it can cause intense pain, temporary blindness and inflammation. If this is what it can do to humans, then it can definitely kill dogs, other household pets and native animals.

6. They’re tough and highly adaptable

Cane toad on white background
© Shutterstock / Chris Ison / WWF

Cane toad habitat ranges from rainforests, coastal mangroves, sand dunes, shrubs and woodlands. They don’t need much water to reproduce. They can also survive temperatures between 5°C - 40°C, so don’t be surprised to find them adapting to survive the cold winters down south.

7. They can lay up to 30,000 eggs twice a year

Male toads start calling for mates after the first summer storm, and they congregate after dark in shallow water where they wait to mount females. Once fertilised, female cane toads lay anywhere between 8,000 to 30,000 eggs - twice a year! These eggs hatch within 1-3 days and tiny tadpoles emerge.

These tadpoles are less than 3.5cm long, and they’ll stay in this phase up to 20 weeks, depending on their food supply. Adult cane toads can live between 5-10 years in the wild.

8. Cane toads eat almost anything

Cane toads will eat anything they swallow - both dead and living. This includes pet food, carrion and household scraps, but mostly they exist on a diet of living insects.

9. They’re on track to reach all the way to the Western Australian coast in two years

They’ve already blasted their way across Queensland and through Kakadu National Park in the Northern Territory where they’ve caused local extinctions of native species.

They typically devastate local native predators by 90% within a few months of arrival. Now, they’re on their march, invading Western Australia and the Kimberley - one of the last biodiversity strongholds in Australia.

10. WWF-Australia is working to help save Australian native species from the cane toad invasion

Cane toad metamorphs in Australia
© Travis Child / WWF-Aus

While we can’t stop the cane toad invasion in the Kimberley, we can help native species survive it. In partnership with the Cane Toad Coalition, WWF-Australia is working to train native predators (like the yellow-spotted monitor, freshwater crocodiles, northern blue-tongue lizard and northern quolls) to recognise and avoid the taste of cane toads. It’s called taste aversion training, and it’s a bit like getting food poisoning at a restaurant and never going back there.

By dropping cane toad sausages and very small cane toads (known as ‘metamorphs’) into vital habitats, native predators are exposed to a small amount of toxin that makes them sick but doesn’t kill them. When they later see and smell a larger adult toad, they’ll know to avoid it. It’s already been trialled with great success in one area of the Kimberley, and we need your help to expand the project.

Will you help native Australian species survive the devastating cane toad invasion?

This work is made possible by the Cane Toad Coalition. A partnership between a group of research, conservation and land management organisations. Partners include Macquarie University; Parks and Wildlife Service Western Australia; Kimberley Land Council; Australian Wildlife Conservancy; Dunkeld Pastoral Co Pty Ltd; Rangelands NRM; Matso’s and WWF-Australia.

This project is supported by Lotterywest.