How ‘trash chickens’ learned to wash poisonous cane toads

Ibis seen eating a toad in Logan, near Brisbane

Few Australian animals are worse than the white ibis.

He has earned the nickname “trash chicken” for his tendency to scavenge food from anywhere he can – haplessly raiding garbage and often stealing food from people’s hands.

But the native bird may have figured out how to restore its bad reputation.

He developed an “ingenious” method to kill one of the only animals Australians hate most – the cane toad, a toxic and pervasive pest.

First introduced to Australia in the 1930s, cane toads have no natural predators in the country and have devastated native animals.

The stingray has venom on its skin that it releases when threatened, causing most animals that come into contact with it to die quickly of a heart attack.

So Emily Vincent was surprised when members of the public started sending her pictures and videos of ibis “playing” with the amphibians.

Ms Vincent, who runs the invasive species programs at environmental charity Watergum, says the behavior has been reported up and down Australia’s east coast.

“Ibis were shedding tears, throwing them in the air, and people were just wondering what on earth they were doing,” she told the BBC.

“After this they would always throw the toads in wet grass, or they would go down to a nearby source of water, and rinse the toads off.”

She believes it is evidence of a “stress, wash and repeat” method that the birds have developed to get rid of the toxins before swallowing them whole.

“It’s really quite amusing.”

‘smart’ birds

This is not the first time birds have been seen eating cane toads, Professor Rick Shine from Macquarie University told the BBC.

They seem to be less susceptible to the poison than other animals, such as snakes, mammals or crocodiles.

Ibis carrying a toad

Toad expert Rick Shine says he has never heard of the behavior before

But they can still die from too much of it and it tastes “horrible”, says Professor Shine.

So as the species spread across Australia, birds like hawks and crows were quickly figuring out how to eat around the poison glands on their shoulders.

They threw the toads on their backs and ripped out their insides, leaving the glands untouched.

But this is the first time Professor Shine – who has studied toes for 20 years – has heard of birds using a method like this to eat them whole.

“Ibis has an unfair reputation… [but] this shows that these are intelligent birds,” says Ms Vincent.

“They forced the cane toad to get rid of the toxin itself, they didn’t have to harm it in any way. The cane toad is doing all the work for them.”

Population control

Both Professor Shine and Ms Vincent say it is a promising sign that native animals are learning to adapt to the toads, which are now estimated to number more than 2 billion.

Some species are slowly recognizing that the pests are a “bad choice for lunch” and there are suggestions that others are making genetic changes that make them less susceptible to the poison.

And then there are animals like the ibis that have worked out how to eat toads safely, which could help bring the population back under control.

“They have an incredible breeding capacity … so for every female cane toad removed from the environment, it’s going to prevent up to 70,000 new cane toads every year,” says Ms Vincent.

Cane toad

As well as poisoning predators, cane toads also feed on small native animals

Most of the heavy lifting is being done by animals Australia loves to hate – like the ibis, rodents or ants – says Professor Shine.

“All these animals are doing a great job as an invisible army that is reducing the number of cane toads every year,” says Professor Shine.

“So we should be grateful for some of the Australians without love.”

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