Cane toads 'wiping out' mini crocodiles Down Under

Jul 03, 2013
A poisonous cane toad sits on a keeper's hand at the Taronga Zoo in Sydney on April 26, 2005. Australia's cane toad is wiping out populations of a unique miniature crocodile, researchers warned Wednesday, with fears the warty, toxic creature could extinguish the rare reptile.

Australia's noxious cane toad is wiping out populations of a unique miniature crocodile, researchers warned Wednesday, with fears the warty, toxic creature could extinguish the rare reptile.

A team from Charles Darwin University studying the impacts of the foul toad in upstream escarpments found "significant declines" in numbers of dwarf freshwater crocodiles after the amphibians' arrival.

Dwarf crocodiles are thought to be stunted due to a lack of available food and researchers believe the crocs started gobbling up the cane toads when they came along.

Lead researcher Adam Britton said there had been 28 of the rare crocs across the study area, around the Victoria and Bullo rivers in the Northern Territory, prior to the arrival of the toads.

The population declined to ten after the toads arrived, the study, conducted from 2007-2008 and published in the latest edition of the journal Wildlife Research, showed.

"Dead crocodiles and evidence of their having eaten cane toads strongly suggest that these declines were caused directly by the arrival of cane toads into the area," the study found.

Dwarf crocodiles, also known as pygmy or "stunted" crocodiles, grow to a maximum of 1.7 metres (five foot six inches), or 0.7 metres (two foot three inches) for females, half the size of other freshwater .

An adult male dwarf crocodile is seen in the Bullo River in Australia's Northern Territory, in this image taken by the Charles Darwin Museum in August 2006. Australia's cane toad is wiping out populations of the unique miniature crocodile, researchers warn.

There is no evidence that the rare pygmy is genetically different to other freshwater crocodiles.

Britton said there was concern that, due to their limited numbers—believed to be in the low hundreds—the pygmy croc could die out altogether due to the cane toad's march.

"We already know that cane toads kill freshwater crocodiles, but we were concerned that might have a major impact on dwarf populations because of their small size and lack of alternative ," Britton said.

"These are low-density populations to begin with," he continued. "They disappeared totally from one study site."

The researcher added: "We still have a long way to go in our understanding of how native populations deal with invasive species."

The study did offer some hope for the crocodiles, with no apparent population change recorded at one site and evidence of behavioural adaptations to avoid the poison by only eating the toad's hind legs.

Cane —warty, leathery creatures with a venom sac on their heads toxic enough to kill snakes and —are advancing across north-western Australia at a speed of 50 kilometres (31 miles) a year.

They were first introduced to Australia from Hawaii to control scarab beetle populations in the 1930s but have now reached pest proportions, breeding prolifically and with few predators.

Native animals, particularly small marsupials and lizards, will die if they eat a full-grown adult.

Explore further: Cane toad or native frog? App prevents mistaken identity

add to favorites email to friend print save as pdf

Related Stories

Australian wildlife taught to shun cane toads

Nov 27, 2012

Australia's native animals are being fed nauseating sausages of cane toad meat in a bid to train them against eating the foul, toxic species as it spreads into new areas, researchers said on Tuesday.

Using the cane toad's poison against itself

Jun 13, 2012

(Phys.org) -- An effective new weapon in the fight against the spread of cane toads has been developed by the University of Sydney, in collaboration with the University of Queensland.

Eradicating cane toads with 'their own medicine'

Nov 14, 2011

Sydney University biologists have discovered cane toad tadpoles (Bufo marinus) communicate using chemicals excreted into the water, a finding that may help to impede the Cane Toad invasion of the Kimberley.

Recommended for you

Chimpanzees prefer firm, stable beds

1 hour ago

Chimpanzees may select a certain type of wood, Ugandan Ironwood, over other options for its firm, stable, and resilient properties to make their bed, according to a study published April 16, 2014 in the open-access ...

Offspring benefit from mum sending the right message

8 hours ago

(Phys.org) —Researchers have uncovered a previously unforeseen interaction between the sexes which reveals that offspring survival is affected by chemical signals emitted from the females' eggs.

Lemurs match scent of a friend to sound of her voice

23 hours ago

Humans aren't alone in their ability to match a voice to a face—animals such as dogs, horses, crows and monkeys are able to recognize familiar individuals this way too, a growing body of research shows.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Anonym
1.6 / 5 (7) Jul 03, 2013
What's this? Somebody notifiy the editor: you forgot to mention the role of "climate change" in this extinction story.;

More news stories

Chimpanzees prefer firm, stable beds

Chimpanzees may select a certain type of wood, Ugandan Ironwood, over other options for its firm, stable, and resilient properties to make their bed, according to a study published April 16, 2014 in the open-access ...

For cells, internal stress leads to unique shapes

From far away, the top of a leaf looks like one seamless surface; however, up close, that smooth exterior is actually made up of a patchwork of cells in a variety of shapes and sizes. Interested in how these ...

Down's chromosome cause genome-wide disruption

The extra copy of Chromosome 21 that causes Down's syndrome throws a spanner into the workings of all the other chromosomes as well, said a study published Wednesday that surprised its authors.

IBM posts lower 1Q earnings amid hardware slump

IBM's first-quarter earnings fell and revenue came in below Wall Street's expectations amid an ongoing decline in its hardware business, one that was exasperated by weaker demand in China and emerging markets.