Magnetic Island’s death adder population thrives due to lack of food source for cane toads

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Cane toads have reduced the population of a deadly reptile by almost 90% in Australia, but on this island they are thriving.

Off Townsville, Magnetic Island is a haven for vacationers, backpackers and vipers.

Listed as the ninth most dangerous snake in Australia, the death viper has a distinctly stocky appearance with brown bands and a distinctive triangular head and lives under the foliage of leaves where it sits and waits for prey.

Their numbers have been declining on the Australian mainland, with scientists reporting that the population of death adders has dropped by 89% in the past 30 years.

Death adders are Australia’s top ambush predator and use neurotoxic venom on their prey.(Provided: Christina Zdenek)

The head of the Venom Evolution Laboratory at the University of Queensland, Dr Christina Zdenek, said the snakes usually feed on frogs and are unable to tell the difference between friend and foe.

The “skillful” hunter prefers skinks

Dr Zdenek said the reason the deadly viper population on Magnetic Island was unaffected could be found in the snakes’ droppings.

A woman smiling and holding a snake in her mouth with rubber gloves on it
Dr. Zdenek says snakes can’t tell the difference between a frog and a cane toad.(Provided: Christina Zdenek)

Dr Zdenek said unlike snakes on the mainland, Magnetic Island’s death adders never had to turn to frogs and toads as a viable food source.

“The theory is [death adders] have never hunted primarily toads on the island,” she said.

She said populations of frogs and toads on Magnetic Island were smaller than in other parts of Australia, but skinks were abundant.

“The skinks are doing very well on the island and may have been for a long time, so [death adders] specialize [at] eat skinks,” Dr. Zdenek said.

While other snakes pursue their prey, death adders are an ambush forager, meaning they wait for prey to come to them.

“They’re super skilled in that they can squirm to mimic a larva in leaf litter to attract prey,” Dr Zdenek said.

A death adder snake is hidden in the leaves but it has a transmitter on its tail which is visible.
Dr. Zdenek has previously tracked death adders on Magnetic Island with tiny radio transmitters.(ABC North Queensland: Dwayne Wyles)

Spotting a death viper can also be a lifelong process.

“Some people will spend years trying to find a death adder, but Magnetic Island is probably one of the only places where you have a good chance of spotting one,” Dr Zdenek said.

Cane toad racing the answer?

People have been gathering for weekly cane toad races at the Arcadia Village Hotel on Magnetic Island for over 40 years.

Every Wednesday evening, a bucket of cane toads is let loose in a circle as eager crowds wait for an amphibian to leap over the edge, taking the top spot.

Lyn Coomber has been a volunteer organizer for over two decades and believed the event had earned its reputation as a world-class race.

Despite participating, she is not a fan of the Cane Toads.

“There are a lot of people who don’t like toadstools, but they still come for the novelty.”

A group of people seated in chairs in a circle with a host standing in the middle
Cane Toad races don’t do much to reduce the population.(ABC North Qld: Paula Tapiolas)

She said that although the toads were often repurposed, they were always happy to accept donations.

“We would love for you to drop off a cane toad…whether on the island or on the mainland, we are very happy to arrange for you to drop them off, or we can collect them for you,” she said .

The races raised more than $2 million for the island’s surf lifesaving club, but the show was unlikely to keep the numbers at bay.

For Dr. Zdenek, the real solution was an aggressive cane toad management plan.

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